forked from mirror/gorm
1111 lines
30 KiB
Markdown
1111 lines
30 KiB
Markdown
# GORM
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The fantastic ORM library for Golang, aims to be developer friendly.
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[](https://app.wercker.com/project/bykey/0cb7bb1039e21b74f8274941428e0921)
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## Overview
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* Chainable API
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* Embedded Structs
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* Relations
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* Callbacks (before/after create/save/update/delete/find)
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* Soft Deletes
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* Auto Migrations
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* Transactions
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* Customizable Logger
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* Iteration Support via [Rows](#row--rows)
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* Scopes
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* sql.Scanner support
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* Polymorphism
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* Every feature comes with tests
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* Convention Over Configuration
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* Developer Friendly
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## Conventions
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* Table name is the plural of struct name's snake case, you can disable pluralization with `db.SingularTable(true)`, or [Specifying The Table Name For A Struct Permanently With TableName](#specifying-the-table-name-for-a-struct-permanently-with-tablename)
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```go
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// E.g finding an existing User
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var user User
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// Gorm will know to use table "users" ("user" if pluralisation has been disabled) for all operations.
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db.First(&user)
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// creating a new User
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db.Save(&User{Name: "xxx"}) // table "users"
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```
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* Column name is the snake case of field's name
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* Use `Id` field as primary key
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* Use tag `sql` to change field's property, change the tag name with `db.SetTagIdentifier(new_name)`
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* Use `CreatedAt` to store record's created time if field exists
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* Use `UpdatedAt` to store record's updated time if field exists
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* Use `DeletedAt` to store record's deleted time if field exists [Soft Delete](#soft-delete)
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# Getting Started
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## Install
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```
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go get -u github.com/jinzhu/gorm
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```
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## Define Models (Structs)
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```go
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type User struct {
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Id int64
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Birthday time.Time
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Age int64
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Name string `sql:"size:255"`
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CreatedAt time.Time
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UpdatedAt time.Time
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DeletedAt time.Time
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Emails []Email // One-To-Many relationship (has many)
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BillingAddress Address // One-To-One relationship (has one)
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BillingAddressId sql.NullInt64 // Foreign key of BillingAddress
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ShippingAddress Address // One-To-One relationship (has one)
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ShippingAddressId int64 // Foreign key of ShippingAddress
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IgnoreMe int64 `sql:"-"` // Ignore this field
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Languages []Language `gorm:"many2many:user_languages;"` // Many-To-Many relationship, 'user_languages' is join table
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}
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type Email struct {
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Id int64
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UserId int64 // Foreign key for User (belongs to)
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Email string `sql:"type:varchar(100);"` // Set field's type
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Subscribed bool
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}
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type Address struct {
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Id int64
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Address1 string `sql:"not null;unique"` // Set field as not nullable and unique
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Address2 string `sql:"type:varchar(100);unique"`
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Post sql.NullString `sql:not null`
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}
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type Language struct {
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Id int64
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Name string
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}
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```
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## Initialize Database
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```go
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import (
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"github.com/jinzhu/gorm"
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_ "github.com/lib/pq"
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_ "github.com/go-sql-driver/mysql"
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_ "github.com/mattn/go-sqlite3"
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)
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db, err := gorm.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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// db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True")
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// db, err := gorm.Open("sqlite3", "/tmp/gorm.db")
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// You can also use an existing database connection handle
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// dbSql, _ := sql.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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// db := gorm.Open("postgres", dbSql)
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// Get database connection handle [*sql.DB](http://golang.org/pkg/database/sql/#DB)
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db.DB()
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// Then you could invoke `*sql.DB`'s functions with it
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db.DB().Ping()
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db.DB().SetMaxIdleConns(10)
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db.DB().SetMaxOpenConns(100)
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// Disable table name's pluralization
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db.SingularTable(true)
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```
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## Migration
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```go
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// Create table
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db.CreateTable(&User{})
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// Drop table
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db.DropTable(&User{})
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// Drop table if exists
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db.DropTableIfExists(&User{})
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// Automating Migration
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db.AutoMigrate(&User{})
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db.AutoMigrate(&User{}, &Product{}, &Order{})
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// Feel free to change your struct, AutoMigrate will keep your database up-to-date.
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// Fyi, AutoMigrate will only *add new columns*, it won't update column's type or delete unused columns, to make sure your data is safe.
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// If the table is not existing, AutoMigrate will create the table automatically.
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// Add index
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db.Model(&User{}).AddIndex("idx_user_name", "name")
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// Multiple column index
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db.Model(&User{}).AddIndex("idx_user_name_age", "name", "age")
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// Add unique index
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db.Model(&User{}).AddUniqueIndex("idx_user_name", "name")
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// Multiple column unique index
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db.Model(&User{}).AddUniqueIndex("idx_user_name_age", "name", "age")
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// Remove index
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db.Model(&User{}).RemoveIndex("idx_user_name")
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```
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# Basic CRUD
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## Create Record
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```go
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user := User{Name: "Jinzhu", Age: 18, Birthday: time.Now()}
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// returns true if record hasn’t been saved (primary key `Id` is blank)
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db.NewRecord(user) // => true
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db.Create(&user)
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// will return false after `user` created
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db.NewRecord(user) // => false
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// You could use `Save` to create record also if its primary key is null
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db.Save(&user)
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// Associations will be saved automatically when insert the record
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user := User{
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Name: "jinzhu",
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BillingAddress: Address{Address1: "Billing Address - Address 1"},
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ShippingAddress: Address{Address1: "Shipping Address - Address 1"},
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Emails: []Email{{Email: "jinzhu@example.com"}, {Email: "jinzhu-2@example@example.com"}},
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Languages: []Language{{Name: "ZH"}, {Name: "EN"}},
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}
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db.Create(&user)
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//// BEGIN TRANSACTION;
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//// INSERT INTO "addresses" (address1) VALUES ("Billing Address - Address 1");
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//// INSERT INTO "addresses" (address1) VALUES ("Shipping Address - Address 1");
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//// INSERT INTO "users" (name,billing_address_id,shipping_address_id) VALUES ("jinzhu", 1, 2);
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//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu@example.com");
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//// INSERT INTO "emails" (user_id,email) VALUES (111, "jinzhu-2@example.com");
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//// INSERT INTO "languages" ("name") VALUES ('ZH');
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//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 1);
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//// INSERT INTO "languages" ("name") VALUES ('EN');
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//// INSERT INTO user_languages ("user_id","language_id") VALUES (111, 2);
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//// COMMIT;
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```
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Refer [Associations](#associations) for how to work with associations
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## Query
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```go
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// Get the first record
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db.First(&user)
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//// SELECT * FROM users ORDER BY id LIMIT 1;
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// Get the last record
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db.Last(&user)
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//// SELECT * FROM users ORDER BY id DESC LIMIT 1;
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// Get all records
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db.Find(&users)
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//// SELECT * FROM users;
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// Get record with primary key
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db.First(&user, 10)
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//// SELECT * FROM users WHERE id = 10;
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```
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### Query With Where (Plain SQL)
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```go
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// Get the first matched record
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db.Where("name = ?", "jinzhu").First(&user)
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//// SELECT * FROM users WHERE name = 'jinzhu' limit 1;
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// Get all matched records
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db.Where("name = ?", "jinzhu").Find(&users)
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//// SELECT * FROM users WHERE name = 'jinzhu';
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db.Where("name <> ?", "jinzhu").Find(&users)
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// IN
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db.Where("name in (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)
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// LIKE
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db.Where("name LIKE ?", "%jin%").Find(&users)
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// AND
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db.Where("name = ? and age >= ?", "jinzhu", "22").Find(&users)
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```
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### Query With Where (Struct & Map)
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```go
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// Struct
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db.Where(&User{Name: "jinzhu", Age: 20}).First(&user)
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//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20 LIMIT 1;
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// Map
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db.Where(map[string]interface{}{"name": "jinzhu", "age": 20}).Find(&users)
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//// SELECT * FROM users WHERE name = "jinzhu" AND age = 20;
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// Slice of primary keys
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db.Where([]int64{20, 21, 22}).Find(&users)
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//// SELECT * FROM users WHERE id IN (20, 21, 22);
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```
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### Query With Not
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```go
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db.Not("name", "jinzhu").First(&user)
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//// SELECT * FROM users WHERE name <> "jinzhu" LIMIT 1;
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// Not In
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db.Not("name", []string{"jinzhu", "jinzhu 2"}).Find(&users)
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//// SELECT * FROM users WHERE name NOT IN ("jinzhu", "jinzhu 2");
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// Not In slice of primary keys
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db.Not([]int64{1,2,3}).First(&user)
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//// SELECT * FROM users WHERE id NOT IN (1,2,3);
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db.Not([]int64{}).First(&user)
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//// SELECT * FROM users;
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// Plain SQL
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db.Not("name = ?", "jinzhu").First(&user)
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//// SELECT * FROM users WHERE NOT(name = "jinzhu");
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// Struct
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db.Not(User{Name: "jinzhu"}).First(&user)
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//// SELECT * FROM users WHERE name <> "jinzhu";
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```
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### Query With Inline Condition
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```go
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// Get by primary key
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db.First(&user, 23)
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//// SELECT * FROM users WHERE id = 23 LIMIT 1;
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// Plain SQL
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db.Find(&user, "name = ?", "jinzhu")
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//// SELECT * FROM users WHERE name = "jinzhu";
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db.Find(&users, "name <> ? AND age > ?", "jinzhu", 20)
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//// SELECT * FROM users WHERE name <> "jinzhu" AND age > 20;
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// Struct
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db.Find(&users, User{Age: 20})
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//// SELECT * FROM users WHERE age = 20;
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// Map
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db.Find(&users, map[string]interface{}{"age": 20})
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//// SELECT * FROM users WHERE age = 20;
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```
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### Query With Or
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```go
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db.Where("role = ?", "admin").Or("role = ?", "super_admin").Find(&users)
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//// SELECT * FROM users WHERE role = 'admin' OR role = 'super_admin';
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// Struct
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db.Where("name = 'jinzhu'").Or(User{Name: "jinzhu 2"}).Find(&users)
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//// SELECT * FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2';
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// Map
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db.Where("name = 'jinzhu'").Or(map[string]interface{}{"name": "jinzhu 2"}).Find(&users)
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```
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### Query Chains
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Gorm has a chainable API, you could use it like this
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```go
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db.Where("name <> ?","jinzhu").Where("age >= ? and role <> ?",20,"admin").Find(&users)
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//// SELECT * FROM users WHERE name <> 'jinzhu' AND age >= 20 AND role <> 'admin';
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db.Where("role = ?", "admin").Or("role = ?", "super_admin").Not("name = ?", "jinzhu").Find(&users)
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```
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## Update
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```go
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// Update an existing struct
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db.First(&user)
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user.Name = "jinzhu 2"
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user.Age = 100
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db.Save(&user)
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//// UPDATE users SET name='jinzhu 2', age=100, updated_at = '2013-11-17 21:34:10' WHERE id=111;
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// Update an attribute if it is changed
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db.Model(&user).Update("name", "hello")
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//// UPDATE users SET name='hello', updated_at = '2013-11-17 21:34:10' WHERE id=111;
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db.First(&user, 111).Update("name", "hello")
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//// SELECT * FROM users LIMIT 1;
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//// UPDATE users SET name='hello', updated_at = '2013-11-17 21:34:10' WHERE id=111;
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// Update multiple attributes if they are changed
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db.Model(&user).Updates(User{Name: "hello", Age: 18})
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//// UPDATE users SET name='hello', age=18, updated_at = '2013-11-17 21:34:10' WHERE id = 111;
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```
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### Update Without Callbacks
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By default, update will call BeforeUpdate, AfterUpdate callbacks, if you want to update w/o callbacks:
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```go
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db.Model(&user).UpdateColumn("name", "hello")
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//// UPDATE users SET name='hello' WHERE id = 111;
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db.Model(&user).UpdateColumns(User{Name: "hello", Age: 18})
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//// UPDATE users SET name='hello', age=18 WHERE id = 111;
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```
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### Batch Updates
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```go
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db.Table("users").Where("id = ?", 10).Updates(map[string]interface{}{"name": "hello", "age": 18})
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//// UPDATE users SET name='hello', age=18 WHERE id = 10;
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db.Model(User{}).Updates(User{Name: "hello", Age: 18})
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//// UPDATE users SET name='hello', age=18;
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// Callbacks won't be run when do batch updates
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// You may would like to know how many records updated when do batch updates
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// You could get it with `RowsAffected`
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db.Model(User{}).Updates(User{Name: "hello", Age: 18}).RowsAffected
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```
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## Delete
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```go
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// Delete an existing record
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db.Delete(&email)
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//// DELETE from emails where id=10;
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```
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### Batch Delete
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```go
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db.Where("email LIKE ?", "%jinzhu%").Delete(Email{})
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//// DELETE from emails where email LIKE "%jinhu%";
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```
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### Soft Delete
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If struct has `DeletedAt` field, it will get soft delete ability automatically!
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Then it won't be deleted from database permanently when call `Delete`.
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```go
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db.Delete(&user)
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//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE id = 111;
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// Batch Delete
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db.Where("age = ?", 20).Delete(&User{})
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//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE age = 20;
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// Soft deleted records will be ignored when query them
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db.Where("age = 20").Find(&user)
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//// SELECT * FROM users WHERE age = 20 AND (deleted_at IS NULL AND deleted_at <= '0001-01-02');
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// Find soft deleted records with Unscoped
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db.Unscoped().Where("age = 20").Find(&users)
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//// SELECT * FROM users WHERE age = 20;
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// Delete record permanently with Unscoped
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db.Unscoped().Delete(&order)
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//// DELETE FROM orders WHERE id=10;
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```
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## Associations
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### Has One
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```go
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// User has one address
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db.Model(&user).Related(&address)
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//// SELECT * FROM addresses WHERE id = 123; // 123 is user's foreign key AddressId
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// Specify the foreign key
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db.Model(&user).Related(&address1, "BillingAddressId")
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//// SELECT * FROM addresses WHERE id = 123; // 123 is user's foreign key BillingAddressId
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```
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### Belongs To
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```go
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// Email belongs to user
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db.Model(&email).Related(&user)
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//// SELECT * FROM users WHERE id = 111; // 111 is email's foreign key UserId
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// Specify the foreign key
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db.Model(&email).Related(&user, "ProfileId")
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//// SELECT * FROM users WHERE id = 111; // 111 is email's foreign key ProfileId
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```
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### Has Many
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```go
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// User has many emails
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db.Model(&user).Related(&emails)
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//// SELECT * FROM emails WHERE user_id = 111;
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// user_id is the foreign key, 111 is user's primary key's value
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// Specify the foreign key
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db.Model(&user).Related(&emails, "ProfileId")
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//// SELECT * FROM emails WHERE profile_id = 111;
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// profile_id is the foreign key, 111 is user's primary key's value
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```
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### Many To Many
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```go
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// User has many languages and belongs to many languages
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db.Model(&user).Related(&languages, "Languages")
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//// SELECT * FROM "languages" INNER JOIN "user_languages" ON "user_languages"."language_id" = "languages"."id" WHERE "user_languages"."user_id" = 111
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// `Languages` is user's column name, this column's tag defined join table like this `gorm:"many2many:user_languages;"`
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```
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There is also a mode used to handle many to many relations easily
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```go
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// Query
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db.Model(&user).Association("Languages").Find(&languages)
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// same as `db.Model(&user).Related(&languages, "Languages")`
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db.Where("name = ?", "ZH").First(&languageZH)
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db.Where("name = ?", "EN").First(&languageEN)
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// Append
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db.Model(&user).Association("Languages").Append([]Language{languageZH, languageEN})
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db.Model(&user).Association("Languages").Append([]Language{{Name: "DE"}})
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db.Model(&user).Association("Languages").Append(Language{Name: "DE"})
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// Delete
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db.Model(&user).Association("Languages").Delete([]Language{languageZH, languageEN})
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db.Model(&user).Association("Languages").Delete(languageZH, languageEN)
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// Replace
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db.Model(&user).Association("Languages").Replace([]Language{languageZH, languageEN})
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db.Model(&user).Association("Languages").Replace(Language{Name: "DE"}, languageEN)
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// Count
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db.Model(&user).Association("Languages").Count()
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// Return the count of languages the user has
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// Clear
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db.Model(&user).Association("Languages").Clear()
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// Remove all relations between the user and languages
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```
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### Polymorphism
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Supports polymorphic has-many and has-one associations.
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```go
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type Cat struct {
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Id int
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Name string
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Toy Toy `gorm:"polymorphic:Owner;"`
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}
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type Dog struct {
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Id int
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Name string
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Toy Toy `gorm:"polymorphic:Owner;"`
|
||
}
|
||
|
||
type Toy struct {
|
||
Id int
|
||
Name string
|
||
OwnerId int
|
||
OwnerType int
|
||
}
|
||
```
|
||
Note: polymorphic belongs-to and many-to-many are explicitly NOT supported, and will throw errors.
|
||
|
||
## Advanced Usage
|
||
|
||
## FirstOrInit
|
||
|
||
Get the first matched record, or initialize a record with search conditions.
|
||
|
||
```go
|
||
// Unfound
|
||
db.FirstOrInit(&user, User{Name: "non_existing"})
|
||
//// user -> User{Name: "non_existing"}
|
||
|
||
// Found
|
||
db.Where(User{Name: "Jinzhu"}).FirstOrInit(&user)
|
||
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
db.FirstOrInit(&user, map[string]interface{}{"name": "jinzhu"})
|
||
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
```
|
||
|
||
### Attrs
|
||
|
||
Ignore some values when searching, but use them to initialize the struct if record is not found.
|
||
|
||
```go
|
||
// Unfound
|
||
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = 'non_existing';
|
||
//// user -> User{Name: "non_existing", Age: 20}
|
||
|
||
db.Where(User{Name: "noexisting_user"}).Attrs("age", 20).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = 'non_existing';
|
||
//// user -> User{Name: "non_existing", Age: 20}
|
||
|
||
// Found
|
||
db.Where(User{Name: "Jinzhu"}).Attrs(User{Age: 30}).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = jinzhu';
|
||
//// user -> User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
```
|
||
|
||
### Assign
|
||
|
||
Ignore some values when searching, but assign it to the result regardless it is found or not.
|
||
|
||
```go
|
||
// Unfound
|
||
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrInit(&user)
|
||
//// user -> User{Name: "non_existing", Age: 20}
|
||
|
||
// Found
|
||
db.Where(User{Name: "Jinzhu"}).Assign(User{Age: 30}).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = jinzhu';
|
||
//// user -> User{Id: 111, Name: "Jinzhu", Age: 30}
|
||
```
|
||
|
||
## FirstOrCreate
|
||
|
||
Get the first matched record, or create with search conditions.
|
||
|
||
```go
|
||
// Unfound
|
||
db.FirstOrCreate(&user, User{Name: "non_existing"})
|
||
//// INSERT INTO "users" (name) VALUES ("non_existing");
|
||
//// user -> User{Id: 112, Name: "non_existing"}
|
||
|
||
// Found
|
||
db.Where(User{Name: "Jinzhu"}).FirstOrCreate(&user)
|
||
//// user -> User{Id: 111, Name: "Jinzhu"}
|
||
```
|
||
|
||
### Attrs
|
||
|
||
Ignore some values when searching, but use them to create the struct if record is not found. like `FirstOrInit`
|
||
|
||
```go
|
||
// Unfound
|
||
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE name = 'non_existing';
|
||
//// INSERT INTO "users" (name, age) VALUES ("non_existing", 20);
|
||
//// user -> User{Id: 112, Name: "non_existing", Age: 20}
|
||
|
||
// Found
|
||
db.Where(User{Name: "jinzhu"}).Attrs(User{Age: 30}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE name = 'jinzhu';
|
||
//// user -> User{Id: 111, Name: "jinzhu", Age: 20}
|
||
```
|
||
|
||
### Assign
|
||
|
||
Ignore some values when searching, but assign it to the record regardless it is found or not, then save back to database. like `FirstOrInit`
|
||
|
||
```go
|
||
// Unfound
|
||
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE name = 'non_existing';
|
||
//// INSERT INTO "users" (name, age) VALUES ("non_existing", 20);
|
||
//// user -> User{Id: 112, Name: "non_existing", Age: 20}
|
||
|
||
// Found
|
||
db.Where(User{Name: "jinzhu"}).Assign(User{Age: 30}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE name = 'jinzhu';
|
||
//// UPDATE users SET age=30 WHERE id = 111;
|
||
//// user -> User{Id: 111, Name: "jinzhu", Age: 30}
|
||
```
|
||
|
||
## Select
|
||
|
||
```go
|
||
db.Select("name, age").Find(&users)
|
||
//// SELECT name, age FROM users;
|
||
|
||
db.Select([]string{"name", "age"}).Find(&users)
|
||
//// SELECT name, age FROM users;
|
||
|
||
db.Table("users").Select("COALESCE(age,?)", 42).Rows()
|
||
//// SELECT COALESCE(age,'42') FROM users;
|
||
```
|
||
|
||
## Order
|
||
|
||
```go
|
||
db.Order("age desc, name").Find(&users)
|
||
//// SELECT * FROM users ORDER BY age desc, name;
|
||
|
||
// Multiple orders
|
||
db.Order("age desc").Order("name").Find(&users)
|
||
//// SELECT * FROM users ORDER BY age desc, name;
|
||
|
||
// ReOrder
|
||
db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
|
||
//// SELECT * FROM users ORDER BY age desc; (users1)
|
||
//// SELECT * FROM users ORDER BY age; (users2)
|
||
```
|
||
|
||
## Limit
|
||
|
||
```go
|
||
db.Limit(3).Find(&users)
|
||
//// SELECT * FROM users LIMIT 3;
|
||
|
||
// Cancel limit condition with -1
|
||
db.Limit(10).Find(&users1).Limit(-1).Find(&users2)
|
||
//// SELECT * FROM users LIMIT 10; (users1)
|
||
//// SELECT * FROM users; (users2)
|
||
```
|
||
|
||
## Offset
|
||
|
||
```go
|
||
db.Offset(3).Find(&users)
|
||
//// SELECT * FROM users OFFSET 3;
|
||
|
||
// Cancel offset condition with -1
|
||
db.Offset(10).Find(&users1).Offset(-1).Find(&users2)
|
||
//// SELECT * FROM users OFFSET 10; (users1)
|
||
//// SELECT * FROM users; (users2)
|
||
```
|
||
|
||
## Count
|
||
|
||
```go
|
||
db.Where("name = ?", "jinzhu").Or("name = ?", "jinzhu 2").Find(&users).Count(&count)
|
||
//// SELECT * from USERS WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (users)
|
||
//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)
|
||
|
||
db.Model(User{}).Where("name = ?", "jinzhu").Count(&count)
|
||
//// SELECT count(*) FROM users WHERE name = 'jinzhu'; (count)
|
||
|
||
db.Table("deleted_users").Count(&count)
|
||
//// SELECT count(*) FROM deleted_users;
|
||
```
|
||
|
||
## Pluck
|
||
|
||
Get selected attributes as map
|
||
|
||
```go
|
||
var ages []int64
|
||
db.Find(&users).Pluck("age", &ages)
|
||
|
||
var names []string
|
||
db.Model(&User{}).Pluck("name", &names)
|
||
|
||
db.Table("deleted_users").Pluck("name", &names)
|
||
|
||
// Requesting more than one column? Do it like this:
|
||
db.Select("name, age").Find(&users)
|
||
```
|
||
|
||
## Raw SQL
|
||
|
||
```go
|
||
db.Exec("DROP TABLE users;")
|
||
db.Exec("UPDATE orders SET shipped_at=? WHERE id IN (?)", time.Now, []int64{11,22,33})
|
||
```
|
||
|
||
## Row & Rows
|
||
|
||
It is even possible to get query result as `*sql.Row` or `*sql.Rows`
|
||
|
||
```go
|
||
row := db.Table("users").Where("name = ?", "jinzhu").Select("name, age").Row() // (*sql.Row)
|
||
row.Scan(&name, &age)
|
||
|
||
rows, err := db.Model(User{}).Where("name = ?", "jinzhu").Select("name, age, email").Rows() // (*sql.Rows, error)
|
||
defer rows.Close()
|
||
for rows.Next() {
|
||
...
|
||
rows.Scan(&name, &age, &email)
|
||
...
|
||
}
|
||
|
||
// Raw SQL
|
||
rows, err := db.Raw("select name, age, email from users where name = ?", "jinzhu").Rows() // (*sql.Rows, error)
|
||
defer rows.Close()
|
||
for rows.Next() {
|
||
...
|
||
rows.Scan(&name, &age, &email)
|
||
...
|
||
}
|
||
```
|
||
|
||
## Scan
|
||
|
||
Scan results into another struct.
|
||
|
||
```go
|
||
type Result struct {
|
||
Name string
|
||
Age int
|
||
}
|
||
|
||
var result Result
|
||
db.Table("users").Select("name, age").Where("name = ?", 3).Scan(&result)
|
||
|
||
// Raw SQL
|
||
db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result)
|
||
```
|
||
|
||
## Group & Having
|
||
|
||
```go
|
||
rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Rows()
|
||
for rows.Next() {
|
||
...
|
||
}
|
||
|
||
rows, err := db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Rows()
|
||
for rows.Next() {
|
||
...
|
||
}
|
||
|
||
type Result struct {
|
||
Date time.Time
|
||
Total int64
|
||
}
|
||
db.Table("orders").Select("date(created_at) as date, sum(amount) as total").Group("date(created_at)").Having("sum(amount) > ?", 100).Scan(&results)
|
||
```
|
||
|
||
## Joins
|
||
|
||
```go
|
||
rows, err := db.Table("users").Select("users.name, emails.email").Joins("left join emails on emails.user_id = users.id").Rows()
|
||
for rows.Next() {
|
||
...
|
||
}
|
||
|
||
db.Table("users").Select("users.name, emails.email").Joins("left join emails on emails.user_id = users.id").Scan(&results)
|
||
```
|
||
|
||
## Transactions
|
||
|
||
All individual save and delete operations are run in a transaction by default.
|
||
|
||
```go
|
||
// begin
|
||
tx := db.Begin()
|
||
|
||
// rollback
|
||
tx.Rollback()
|
||
|
||
// commit
|
||
tx.Commit()
|
||
```
|
||
|
||
## Scopes
|
||
|
||
```go
|
||
func AmountGreaterThan1000(db *gorm.DB) *gorm.DB {
|
||
return db.Where("amount > ?", 1000)
|
||
}
|
||
|
||
func PaidWithCreditCard(db *gorm.DB) *gorm.DB {
|
||
return db.Where("pay_mode_sign = ?", "C")
|
||
}
|
||
|
||
func PaidWithCod(db *gorm.DB) *gorm.DB {
|
||
return db.Where("pay_mode_sign = ?", "C")
|
||
}
|
||
|
||
func OrderStatus(status []string) func (db *gorm.DB) *gorm.DB {
|
||
return func (db *gorm.DB) *gorm.DB {
|
||
return db.Scopes(AmountGreaterThan1000).Where("status in (?)", status)
|
||
}
|
||
}
|
||
|
||
db.Scopes(AmountGreaterThan1000, PaidWithCreditCard).Find(&orders)
|
||
// Find all credit card orders and amount greater than 1000
|
||
|
||
db.Scopes(AmountGreaterThan1000, PaidWithCod).Find(&orders)
|
||
// Find all COD orders and amount greater than 1000
|
||
|
||
db.Scopes(OrderStatus([]string{"paid", "shipped"})).Find(&orders)
|
||
// Find all paid, shipped orders
|
||
```
|
||
|
||
## Callbacks
|
||
|
||
Callbacks are methods defined on the pointer of struct.
|
||
If any callback returns an error, gorm will stop future operations and rollback all changes.
|
||
|
||
Here is the list of all available callbacks:
|
||
(listed in the same order in which they will get called during the respective operations)
|
||
|
||
### Creating An Object
|
||
|
||
```go
|
||
BeforeSave
|
||
BeforeCreate
|
||
// save before associations
|
||
// save self
|
||
// save after associations
|
||
AfterCreate
|
||
AfterSave
|
||
```
|
||
### Updating An Object
|
||
|
||
```go
|
||
BeforeSave
|
||
BeforeUpdate
|
||
// save before associations
|
||
// save self
|
||
// save after associations
|
||
AfterUpdate
|
||
AfterSave
|
||
```
|
||
|
||
### Destroying An Object
|
||
|
||
```go
|
||
BeforeDelete
|
||
// delete self
|
||
AfterDelete
|
||
```
|
||
|
||
### After Find
|
||
|
||
```go
|
||
// load data from database
|
||
AfterFind
|
||
```
|
||
|
||
### Example
|
||
|
||
```go
|
||
func (u *User) BeforeUpdate() (err error) {
|
||
if u.readonly() {
|
||
err = errors.New("read only user")
|
||
}
|
||
return
|
||
}
|
||
|
||
// Rollback the insertion if user's id greater than 1000
|
||
func (u *User) AfterCreate() (err error) {
|
||
if (u.Id > 1000) {
|
||
err = errors.New("user id is already greater than 1000")
|
||
}
|
||
return
|
||
}
|
||
```
|
||
|
||
As you know, save/delete operations in gorm are running in a transaction,
|
||
This is means if changes made in the transaction is not visiable unless it is commited,
|
||
So if you want to use those changes in your callbacks, you need to run SQL in same transaction.
|
||
Fortunately, gorm support pass transaction to callbacks as you needed, you could do it like this:
|
||
|
||
```go
|
||
func (u *User) AfterCreate(tx *gorm.DB) (err error) {
|
||
tx.Model(u).Update("role", "admin")
|
||
return
|
||
}
|
||
```
|
||
|
||
## Specifying The Table Name
|
||
|
||
```go
|
||
// Create `deleted_users` table with struct User's definition
|
||
db.Table("deleted_users").CreateTable(&User{})
|
||
|
||
var deleted_users []User
|
||
db.Table("deleted_users").Find(&deleted_users)
|
||
//// SELECT * FROM deleted_users;
|
||
|
||
db.Table("deleted_users").Where("name = ?", "jinzhu").Delete()
|
||
//// DELETE FROM deleted_users WHERE name = 'jinzhu';
|
||
```
|
||
|
||
### Specifying The Table Name For A Struct Permanently with TableName
|
||
|
||
```go
|
||
type Cart struct {
|
||
}
|
||
|
||
func (c Cart) TableName() string {
|
||
return "shopping_cart"
|
||
}
|
||
|
||
func (u User) TableName() string {
|
||
if u.Role == "admin" {
|
||
return "admin_users"
|
||
} else {
|
||
return "users"
|
||
}
|
||
}
|
||
```
|
||
|
||
## Error Handling
|
||
|
||
```go
|
||
query := db.Where("name = ?", "jinzhu").First(&user)
|
||
query := db.First(&user).Limit(10).Find(&users)
|
||
// query.Error will return the last happened error
|
||
|
||
// So you could do error handing in your application like this:
|
||
if err := db.Where("name = ?", "jinzhu").First(&user).Error; err != nil {
|
||
// error handling...
|
||
}
|
||
|
||
// RecordNotFound
|
||
// If no record found when you query data, gorm will return RecordNotFound error, you could check it like this:
|
||
db.Where("name = ?", "hello world").First(&User{}).Error == gorm.RecordNotFound
|
||
// Or use the shortcut method
|
||
db.Where("name = ?", "hello world").First(&user).RecordNotFound()
|
||
|
||
if db.Model(&user).Related(&credit_card).RecordNotFound() {
|
||
// no credit card found error handling
|
||
}
|
||
```
|
||
|
||
## Logger
|
||
|
||
Gorm has built-in logger support
|
||
|
||
```go
|
||
// Enable Logger
|
||
db.LogMode(true)
|
||
|
||
// Diable Logger
|
||
db.LogMode(false)
|
||
|
||
// Debug a single operation
|
||
db.Debug().Where("name = ?", "jinzhu").First(&User{})
|
||
```
|
||
|
||
|
||
|
||
### Customize Logger
|
||
|
||
```go
|
||
// Refer gorm's default logger for how to: https://github.com/jinzhu/gorm/blob/master/logger.go#files
|
||
db.SetLogger(gorm.Logger{revel.TRACE})
|
||
db.SetLogger(log.New(os.Stdout, "\r\n", 0))
|
||
```
|
||
|
||
## Existing Schema
|
||
|
||
If you have an existing database schema, and the primary key field is different from `id`, you can add a tag to the field structure to specify that this field is a primary key.
|
||
|
||
```go
|
||
type Animal struct {
|
||
AnimalId int64 `gorm:"primary_key:yes"`
|
||
Birthday time.Time `sql:"DEFAULT:current_timestamp"`
|
||
Name string `sql:"default:'galeone'"`
|
||
Age int64
|
||
}
|
||
```
|
||
|
||
If your column names differ from the struct fields, you can specify them like this:
|
||
|
||
```go
|
||
type Animal struct {
|
||
AnimalId int64 `gorm:"column:beast_id; primary_key:yes"`
|
||
Birthday time.Time `gorm:"column:day_of_the_beast"`
|
||
Age int64 `gorm:"column:age_of_the_beast"`
|
||
}
|
||
```
|
||
|
||
## Default values
|
||
|
||
If you have defined a default value in the `sql` tag (see the struct Animal above) the generated create/update SQl will ignore these fields if is set blank data.
|
||
|
||
Eg.
|
||
|
||
```go
|
||
db.Create(&Animal{Age: 99, Name: ""})
|
||
```
|
||
|
||
The generated query will be:
|
||
|
||
```sql
|
||
INSERT INTO animals("age") values('99');
|
||
```
|
||
|
||
The same thing occurs in update statements.
|
||
|
||
## More examples with query chain
|
||
|
||
```go
|
||
db.First(&first_article).Count(&total_count).Limit(10).Find(&first_page_articles).Offset(10).Find(&second_page_articles)
|
||
//// SELECT * FROM articles LIMIT 1; (first_article)
|
||
//// SELECT count(*) FROM articles; (total_count)
|
||
//// SELECT * FROM articles LIMIT 10; (first_page_articles)
|
||
//// SELECT * FROM articles LIMIT 10 OFFSET 10; (second_page_articles)
|
||
|
||
|
||
db.Where("created_at > ?", "2013-10-10").Find(&cancelled_orders, "state = ?", "cancelled").Find(&shipped_orders, "state = ?", "shipped")
|
||
//// SELECT * FROM orders WHERE created_at > '2013/10/10' AND state = 'cancelled'; (cancelled_orders)
|
||
//// SELECT * FROM orders WHERE created_at > '2013/10/10' AND state = 'shipped'; (shipped_orders)
|
||
|
||
|
||
// Use variables to keep query chain
|
||
todays_orders := db.Where("created_at > ?", "2013-10-29")
|
||
cancelled_orders := todays_orders.Where("state = ?", "cancelled")
|
||
shipped_orders := todays_orders.Where("state = ?", "shipped")
|
||
|
||
|
||
// Search with shared conditions for different tables
|
||
db.Where("product_name = ?", "fancy_product").Find(&orders).Find(&shopping_carts)
|
||
//// SELECT * FROM orders WHERE product_name = 'fancy_product'; (orders)
|
||
//// SELECT * FROM carts WHERE product_name = 'fancy_product'; (shopping_carts)
|
||
|
||
|
||
// Search with shared conditions from different tables with specified table
|
||
db.Where("mail_type = ?", "TEXT").Find(&users1).Table("deleted_users").Find(&users2)
|
||
//// SELECT * FROM users WHERE mail_type = 'TEXT'; (users1)
|
||
//// SELECT * FROM deleted_users WHERE mail_type = 'TEXT'; (users2)
|
||
|
||
|
||
// FirstOrCreate example
|
||
db.Where("email = ?", "x@example.org").Attrs(User{RegisteredIp: "111.111.111.111"}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE email = 'x@example.org';
|
||
//// INSERT INTO "users" (email,registered_ip) VALUES ("x@example.org", "111.111.111.111") // if record not found
|
||
```
|
||
|
||
## TODO
|
||
* db.RegisterFuncation("Search", func() {})
|
||
db.Model(&[]User{}).Limit(10).Do("Search", "search func's argument")
|
||
db.Mode(&User{}).Do("EditForm").Get("edit_form_html")
|
||
DefaultTimeZone, R/W Splitting, Validation
|
||
* Github Pages
|
||
* Includes
|
||
* AlertColumn, DropColumn
|
||
|
||
# Author
|
||
|
||
**jinzhu**
|
||
|
||
* <http://github.com/jinzhu>
|
||
* <wosmvp@gmail.com>
|
||
* <http://twitter.com/zhangjinzhu>
|
||
|
||
## License
|
||
|
||
Released under the [MIT License](http://www.opensource.org/licenses/MIT).
|
||
|
||
[](http://godoc.org/github.com/jinzhu/gorm)
|