mirror of https://github.com/go-gorm/gorm.git
1077 lines
29 KiB
Markdown
1077 lines
29 KiB
Markdown
# GORM
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The fantastic ORM library for Golang, aims to be developer friendly.
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## Install
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```
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go get github.com/jinzhu/gorm
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```
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## Overview
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* Chainable API
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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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* Logger Support
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* Bind struct with tag
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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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* 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.
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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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* Column name is the snake case of field's name.
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* Use `Id int64` 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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* Gorm uses reflection to know which tables to work with:
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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 now 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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// E.g creating a new User
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DB.Save(&User{Name: "xxx"}) // table "users"
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```
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## Existing Schema
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If you have an existing database schema and some of your tables do not follow the conventions, (and you can't rename your table names), please use: [Specifying The Table Name For A Struct Permanently With TableName](#specifying-the-table-name-for-a-struct-permanently-with-tableName).
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If your 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.
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```go
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type Animal struct { // animals
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AnimalId int64 `primaryKey:"yes"`
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Birthday time.Time
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Age int64
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}
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```
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# Getting Started
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```go
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import (
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"database/sql"
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"time"
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)
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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 // Embedded structs
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BillingAddress Address // Embedded struct
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BillingAddressId sql.NullInt64 // BillingAddress's foreign key
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ShippingAddress Address // Another Embedded struct with same type
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ShippingAddressId int64 // ShippingAddress's foreign key
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IgnoreMe int64 `sql:"-"` // Ignore this field
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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
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Email string `sql:"type:varchar(100);"` // Set this 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 this field as not nullable and unique in database
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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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// FYI, "NOT NULL" will only work well with NullXXX Scanner, because golang will initalize a default value for most type...
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}
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```
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## Opening a Database
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```go
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import "github.com/jinzhu/gorm"
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import _ "github.com/lib/pq"
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// import _ "github.com/go-sql-driver/mysql"
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// import _ "github.com/mattn/go-sqlite3"
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db, err := gorm.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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// db, err = gorm.Open("mysql", "gorm:gorm@/gorm?charset=utf8&parseTime=True")
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// db, err = gorm.Open("sqlite3", "/tmp/gorm.db")
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// Get database connection handle [*sql.DB](http://golang.org/pkg/database/sql/#DB)
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d := db.DB()
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// With it you could use package `database/sql`'s builtin methods
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db.DB().SetMaxIdleConns(10)
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db.DB().SetMaxOpenConns(100)
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db.DB().Ping()
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// By default, table name is plural of struct type, you can use struct type as table name with:
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db.SingularTable(true)
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```
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Gorm is goroutines friendly, so you can create a global variable to keep the connection and use it everywhere in your project.
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```go
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// db.go
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package db
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import (
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"fmt"
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"github.com/jinzhu/gorm"
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_ "github.com/lib/pq"
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)
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var DB gorm.DB
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func init() {
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var err error
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DB, err = gorm.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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// Connection string parameters for Postgres - http://godoc.org/github.com/lib/pq, if you are using another
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// database refer to the relevant driver's documentation.
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// * dbname - The name of the database to connect to
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// * user - The user to sign in as
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// * password - The user's password
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// * host - The host to connect to. Values that start with / are for unix domain sockets.
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// (default is localhost)
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// * port - The port to bind to. (default is 5432)
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// * sslmode - Whether or not to use SSL (default is require, this is not the default for libpq)
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// Valid SSL modes:
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// * disable - No SSL
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// * require - Always SSL (skip verification)
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// * verify-full - Always SSL (require verification)
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if err != nil {
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panic(fmt.Sprintf("Got error when connect database, the error is '%v'", err))
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}
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}
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// user.go
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package user
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import . "db"
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...
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DB.Save(&User{Name: "xxx"})
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...
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```
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## Struct & Database Mapping
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```go
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// Create table from struct
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db.CreateTable(User{})
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// Drop table
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db.DropTable(User{})
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```
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### Automating Migrations
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Feel free to update your struct, AutoMigrate will keep your database up-to-date.
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FYI, AutoMigrate will only add new columns, it won't change the current columns' types or delete unused columns, to make sure your data is safe.
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If the table doesn't exist when AutoMigrate is called, gorm will create the table automatically.
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(the database first needs to be created manually though...).
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```go
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db.AutoMigrate(User{})
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```
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# Gorm API
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## Create
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```go
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user := User{Name: "jinzhu", Age: 18, Birthday: time.Now()}
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db.Save(&user)
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// create with predefined primary key
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db.Create(&User{Id: 999, Name: "user 999"})
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```
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### NewRecord
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Returns true if object hasn’t been saved yet (`Id` is blank)
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```go
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user := User{Name: "jinzhu", Age: 18, Birthday: time.Now()}
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db.NewRecord(user) // => true
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db.Save(&user)
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db.NewRecord(user) // => false
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```
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### Create With SubStruct
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Refer to [Query With Related](#query-with-related) for how to find associations
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```go
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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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}
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db.Save(&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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//// COMMIT;
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```
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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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// Search table `users` is guessed from struct's type
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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 (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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//// SELECT * FROM users WHERE name <> 'jinzhu';
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// IN
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db.Where("name in (?)", []string{"jinzhu", "jinzhu 2"}).Find(&users)
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//// SELECT * FROM users WHERE name IN ('jinzhu', 'jinzhu 2');
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// LIKE
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db.Where("name LIKE ?", "%jin%").Find(&users)
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//// SELECT * FROM users WHERE name LIKE "%jin%";
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// Multiple conditions
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db.Where("name = ? and age >= ?", "jinzhu", "22").Find(&users)
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//// SELECT * FROM users WHERE name = 'jinzhu' AND age >= 22;
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```
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### Query With Where (Struct & Map)
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```go
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// Search with 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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// Search with 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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// IN for 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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// Attribute Not Equal
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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 for 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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// SQL string
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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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// Not with 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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// Find with 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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// SQL string
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db.Find(&user, "name = ?", "jinzhu")
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//// SELECT * FROM users WHERE name = "jinzhu";
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// Multiple conditions
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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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// Inline search with 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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// Inline search with 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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// Or With 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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// Or With 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 With Related
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```go
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// Find user's emails with guessed foreign key
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db.Model(&user).Related(&emails)
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//// SELECT * FROM emails WHERE user_id = 111;
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// Find user's billing address with specified foreign key 'BillingAddressId'
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db.Model(&user).Related(&address1, "BillingAddressId")
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//// SELECT * FROM addresses WHERE id = 123; // 123 is user's BillingAddressId
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// Find user with guessed primary key value from email
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db.Model(&email).Related(&user)
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//// SELECT * FROM users WHERE id = 111; // 111 is email's UserId
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```
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### Query Chains
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Gorm has a chainable API, so you could query 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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### Update An Existing Struct
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```go
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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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```
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### Update One Attribute With `Update`
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```go
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// Update existing user's name 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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// Find out a user, and update the name if it is changed
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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 name with search condiation and specified table name
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db.Table("users").Where(10).Update("name", "hello")
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//// UPDATE users SET name='hello' WHERE id = 10;
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```
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### Update Multiple Attributes With `Updates`
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```go
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// Update user's name and age 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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// Updates with Map
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db.Table("users").Where(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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// Updates with Struct
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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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```
|
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|
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### Update Attributes Without 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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|
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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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|
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### Get Affected Records Count
|
||
|
||
```go
|
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db.Model(User{}).Updates(User{Name: "hello", Age: 18}).RowsAffected
|
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```
|
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## Delete
|
||
|
||
### Delete An Existing Struct
|
||
|
||
```go
|
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db.Delete(&email)
|
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// DELETE from emails where id=10;
|
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```
|
||
|
||
### Batch Delete With Search
|
||
|
||
```go
|
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db.Where("email LIKE ?", "%jinzhu%").Delete(Email{})
|
||
// DELETE from emails where email LIKE "%jinhu%";
|
||
```
|
||
|
||
### Soft Delete
|
||
|
||
If a struct has a DeletedAt field, it will get a soft delete ability automatically!
|
||
|
||
Structs that don't have a DeletedAt field will be deleted from the database permanently.
|
||
|
||
```go
|
||
db.Delete(&user)
|
||
//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE id = 111;
|
||
|
||
// Delete with search condition
|
||
db.Where("age = ?", 20).Delete(&User{})
|
||
//// UPDATE users SET deleted_at="2013-10-29 10:23" WHERE age = 20;
|
||
|
||
// Soft deleted records will be ignored when searched
|
||
db.Where("age = 20").Find(&user)
|
||
//// SELECT * FROM users WHERE age = 100 AND (deleted_at IS NULL AND deleted_at <= '0001-01-02');
|
||
|
||
// Find soft deleted records with Unscoped
|
||
db.Unscoped().Where("age = 20").Find(&users)
|
||
//// SELECT * FROM users WHERE age = 20;
|
||
|
||
// Delete record permanently with Unscoped
|
||
db.Unscoped().Delete(&order)
|
||
// DELETE FROM orders WHERE id=10;
|
||
```
|
||
|
||
## FirstOrInit
|
||
|
||
Try to get the first record, if failed, will initialize the struct with search conditions.
|
||
|
||
(only supports search conditions map and struct)
|
||
|
||
```go
|
||
db.FirstOrInit(&user, User{Name: "non_existing"})
|
||
//// User{Name: "non_existing"}
|
||
|
||
db.Where(User{Name: "Jinzhu"}).FirstOrInit(&user)
|
||
//// User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
|
||
db.FirstOrInit(&user, map[string]interface{}{"name": "jinzhu"})
|
||
//// User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
```
|
||
|
||
### FirstOrInit With Attrs
|
||
|
||
Ignore Attrs's arguments when searching, but use them to initialize the struct if no record is found.
|
||
|
||
```go
|
||
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = 'non_existing';
|
||
//// User{Name: "non_existing", Age: 20}
|
||
|
||
// Or write it like this if has only one attribute
|
||
db.Where(User{Name: "noexisting_user"}).Attrs("age", 20).FirstOrInit(&user)
|
||
|
||
// If a record found, Attrs would be ignored
|
||
db.Where(User{Name: "Jinzhu"}).Attrs(User{Age: 30}).FirstOrInit(&user)
|
||
//// SELECT * FROM USERS WHERE name = jinzhu';
|
||
//// User{Id: 111, Name: "Jinzhu", Age: 20}
|
||
```
|
||
|
||
### FirstOrInit With Assign
|
||
|
||
Ignore Assign's arguments when searching, but use them to fill the struct regardless, whether the record is found or not.
|
||
|
||
```go
|
||
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrInit(&user)
|
||
//// User{Name: "non_existing", Age: 20}
|
||
|
||
db.Where(User{Name: "Jinzhu"}).Assign(User{Age: 30}).FirstOrInit(&user)
|
||
//// User{Id: 111, Name: "Jinzhu", Age: 30}
|
||
```
|
||
|
||
## FirstOrCreate
|
||
|
||
Try to get the first record, if failed, will initialize the struct with the search conditions and insert it in the database.
|
||
|
||
```go
|
||
db.FirstOrCreate(&user, User{Name: "non_existing"})
|
||
//// User{Id: 112, Name: "non_existing"}
|
||
|
||
db.Where(User{Name: "Jinzhu"}).FirstOrCreate(&user)
|
||
//// User{Id: 111, Name: "Jinzhu"}
|
||
|
||
db.FirstOrCreate(&user, map[string]interface{}{"name": "jinzhu", "age": 30})
|
||
//// user -> User{Id: 111, Name: "jinzhu", Age: 20}
|
||
```
|
||
|
||
### FirstOrCreate With Attrs
|
||
|
||
Ignore Attrs's arguments when searching, but use them to initialize the struct if no record is found.
|
||
|
||
```go
|
||
db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrCreate(&user)
|
||
//// SELECT * FROM users WHERE name = 'non_existing';
|
||
//// User{Id: 112, Name: "non_existing", Age: 20}
|
||
|
||
db.Where(User{Name: "jinzhu"}).Attrs(User{Age: 30}).FirstOrCreate(&user)
|
||
//// User{Id: 111, Name: "jinzhu", Age: 20}
|
||
```
|
||
|
||
### FirstOrCreate With Assign
|
||
|
||
Ignore Assign's arguments when searching, but use them to fill the struct regardless, whether the record is found or not, then save it back to the database.
|
||
|
||
```go
|
||
db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrCreate(&user)
|
||
//// user -> User{Id: 112, Name: "non_existing", Age: 20}
|
||
|
||
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{Id: 111, Name: "jinzhu", Age: 30}
|
||
```
|
||
|
||
## Select
|
||
|
||
```go
|
||
db.Select("name, age").Find(&users)
|
||
//// SELECT name, age 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;
|
||
|
||
// Remove limit 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;
|
||
|
||
// Remove offset 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)
|
||
|
||
// Set table name with Model
|
||
db.Model(User{}).Where("name = ?", "jinzhu").Count(&count)
|
||
//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)
|
||
|
||
// Set table name with Table
|
||
db.Table("deleted_users").Count(&count)
|
||
//// SELECT count(*) FROM deleted_users;
|
||
```
|
||
|
||
## Pluck
|
||
|
||
Get struct's selected attributes as a map.
|
||
|
||
```go
|
||
var ages []int64
|
||
db.Find(&users).Pluck("age", &ages)
|
||
|
||
// Set Table With Model
|
||
var names []string
|
||
db.Model(&User{}).Pluck("name", &names)
|
||
//// SELECT name FROM users;
|
||
|
||
// Set Table With Table
|
||
db.Table("deleted_users").Pluck("name", &names)
|
||
//// SELECT name FROM deleted_users;
|
||
|
||
// Plucking more than one column? Do it like this:
|
||
db.Select("name, age").Find(&users)
|
||
```
|
||
|
||
## Transactions
|
||
All individual save and delete operations are run in a transaction by default.
|
||
|
||
```go
|
||
tx := db.Begin()
|
||
|
||
user := User{Name: "transcation"}
|
||
|
||
tx.Save(&u)
|
||
tx.Update("age": 90)
|
||
// do whatever
|
||
|
||
// rollback
|
||
tx.Rollback()
|
||
|
||
// commit
|
||
tx.Commit()
|
||
```
|
||
|
||
## Callbacks
|
||
|
||
Callbacks are methods defined on the struct's pointer.
|
||
If any callback returns an error, gorm will stop future operations and rollback all changes.
|
||
|
||
Here is a 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 record/records from database
|
||
AfterFind
|
||
```
|
||
|
||
Here is an example:
|
||
|
||
```go
|
||
func (u *User) BeforeUpdate() (err error) {
|
||
if u.readonly() {
|
||
err = errors.New("Read Only User!")
|
||
}
|
||
return
|
||
}
|
||
|
||
// Rollback the insertion if there are more than 1000 users (hypothetical example)
|
||
func (u *User) AfterCreate() (err error) {
|
||
if (u.Id > 1000) { // Just as an example, don't use Id to count users!
|
||
err = errors.New("Only 1000 users allowed!")
|
||
}
|
||
return
|
||
}
|
||
```
|
||
|
||
```go
|
||
// As you know, the save/delete operations are running in a transaction
|
||
// This is means that all your changes will be rolled back if there are any errors
|
||
// If you want your changes in callbacks be run in the same transaction
|
||
// you have to pass the transaction as argument to the function
|
||
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 User's fields
|
||
db.Table("deleted_users").CreateTable(&User{})
|
||
|
||
// Search from table `deleted_users`
|
||
var deleted_users []User
|
||
db.Table("deleted_users").Find(&deleted_users)
|
||
//// SELECT * FROM deleted_users;
|
||
|
||
// Delete results from table `deleted_users` with search conditions
|
||
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"
|
||
}
|
||
}
|
||
```
|
||
|
||
## Scopes
|
||
|
||
```go
|
||
func AmountGreaterThan1000(d *gorm.DB) *gorm.DB {
|
||
d.Where("amount > ?", 1000)
|
||
}
|
||
|
||
func PaidWithCreditCard(d *gorm.DB) *gorm.DB {
|
||
d.Where("pay_mode_sign = ?", "C")
|
||
}
|
||
|
||
func PaidWithCod(d *gorm.DB) *gorm.DB {
|
||
d.Where("pay_mode_sign = ?", "C")
|
||
}
|
||
|
||
func OrderStatus(status []string) func (d *gorm.DB) *gorm.DB {
|
||
return func (d *gorm.DB) *gorm.DB {
|
||
return d.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 and amount greater than 1000
|
||
```
|
||
|
||
## Logger
|
||
|
||
Gorm has built-in logger support, enable it with:
|
||
|
||
```go
|
||
db.LogMode(true)
|
||
```
|
||
|
||
|
||
|
||
```go
|
||
// Use your own logger
|
||
// Refer to gorm's default logger for how to format messages: https://github.com/jinzhu/gorm/blob/master/logger.go#files
|
||
db.SetLogger(log.New(os.Stdout, "\r\n", 0))
|
||
|
||
// If you want to use gorm's default log format, then you could just do it like this
|
||
db.SetLogger(gorm.Logger{revel.TRACE})
|
||
|
||
// Disable logging
|
||
db.LogMode(false)
|
||
|
||
// Enable logging for a single operation, to make debugging easy
|
||
db.Debug().Where("name = ?", "jinzhu").First(&User{})
|
||
```
|
||
|
||
## Row & Rows
|
||
|
||
Row & Rows is not chainable, it works just like `QueryRow` and `Query`.
|
||
|
||
```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)
|
||
...
|
||
}
|
||
|
||
// Rows() with 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 sql results into a struct.
|
||
|
||
```go
|
||
type Result struct {
|
||
Name string
|
||
Age int
|
||
}
|
||
|
||
var result Result
|
||
db.Table("users").Select("name, age").Where("name = ?", 3).Scan(&result)
|
||
|
||
// Scan 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)
|
||
```
|
||
|
||
## Indices
|
||
|
||
```go
|
||
// single column index
|
||
db.Model(User{}).AddIndex("idx_user_name", "name")
|
||
|
||
// multiple column index
|
||
db.Model(User{}).AddIndex("idx_user_name_age", "name", "age")
|
||
|
||
// single column unique index
|
||
db.Model(User{}).AddUniqueIndex("idx_user_name", "name")
|
||
|
||
// multiple column unique index
|
||
db.Model(User{}).AddUniqueIndex("idx_user_name_age", "name", "age")
|
||
|
||
// remove index
|
||
db.Model(User{}).RemoveIndex("idx_user_name")
|
||
```
|
||
|
||
## Run Raw SQL
|
||
|
||
```go
|
||
// Raw SQL
|
||
db.Exec("DROP TABLE users;")
|
||
|
||
// Raw SQL with arguments
|
||
db.Exec("UPDATE orders SET shipped_at=? WHERE id IN (?)", time.Now, []int64{11,22,33})
|
||
```
|
||
|
||
## Error Handling
|
||
|
||
```go
|
||
query := db.Where("name = ?", "jinzhu").First(&user)
|
||
query := db.First(&user).Limit(10).Find(&users)
|
||
//// query.Error returns the last error
|
||
//// query.Errors returns all errors that have taken place
|
||
//// If an error has taken place, gorm will stop all following operations
|
||
|
||
// I often use some code like below to do error handling when writing applications
|
||
if err := db.Where("name = ?", "jinzhu").First(&user).Error; err != nil {
|
||
// ...
|
||
}
|
||
|
||
// If no record is found, gorm will return RecordNotFound error, you could check it with
|
||
db.Where("name = ?", "hello world").First(&User{}).Error == gorm.RecordNotFound
|
||
|
||
// Or use the shortcut method
|
||
if db.Where("name = ?", "hello world").First(&user).RecordNotFound() {
|
||
panic("no record found")
|
||
} else {
|
||
user.Blalala()
|
||
}
|
||
|
||
if db.Model(&user).Related(&credit_card).RecordNotFound() {
|
||
panic("no credit card found")
|
||
}
|
||
```
|
||
|
||
## Advanced Usage With Query Chaining
|
||
|
||
Already excited with what gorm has to offer? Let's see some magic!
|
||
|
||
```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)
|
||
|
||
|
||
// Mix where conditions with inline conditions
|
||
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 from 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)
|
||
|
||
|
||
// An example on how to use FirstOrCreate
|
||
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 no record found
|
||
```
|
||
|
||
## TODO
|
||
* Support plugin
|
||
BeforeQuery
|
||
BeforeSave
|
||
BeforeCreate
|
||
BeforeUpdate
|
||
BeforeDelete
|
||
AfterQuery
|
||
AfterSave
|
||
AfterCreate
|
||
AfterUpdate
|
||
SoftDelete
|
||
BeforeQuery
|
||
BeforeSave
|
||
BeforeDelete
|
||
|
||
db.RegisterPlugin("xxx")
|
||
db.RegisterCallback("BeforeQuery", func() {})
|
||
db.RegisterCallback("BeforeSave", func() {})
|
||
db.RegisterFuncation("Search", func() {})
|
||
db.Model(&[]User{}).Limit(10).Do("Search", "vip", "china")
|
||
db.Mode(&User{}).Do("EditForm").Get("edit_form_html")
|
||
|
||
DefaultValue, DefaultTimeZone, R/W Splitting, Validation
|
||
* Getter/Setter
|
||
share or not? transaction?
|
||
* 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)
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