forked from mirror/gorm
682 lines
19 KiB
Markdown
682 lines
19 KiB
Markdown
# GORM
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Yet Another ORM library for Go, aims for developer friendly
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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)
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* Soft Delete
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* Auto Migration
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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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```go
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type User struct { // TableName: `users`, gorm will pluralize struct's name as table name
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Id int64 // Id: Database Primary key
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Birthday time.Time
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Age int64
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Name string
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CreatedAt time.Time // Time of record is created, will be insert automatically
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UpdatedAt time.Time // Time of record is updated, will be updated automatically
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DeletedAt time.Time // Time of record is deleted, refer `Soft Delete` for more
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Email []Email // Embedded structs
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BillingAddress Address // Embedded struct
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BillingAddressId sql.NullInt64 // Embedded struct BillingAddress's foreign key
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ShippingAddress Address // Embedded struct
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ShippingAddressId int64 // Embedded struct ShippingAddress's foreign key
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}
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type Email struct { // TableName: `emails`
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Id int64
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UserId int64 // Foreign key for above embedded structs
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Email string
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Subscribed bool
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}
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type Address struct { // TableName: `addresses`
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Id int64
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Address1 string
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Address2 string
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Post string
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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 := Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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// db, err = Open("mysql", "gorm:gorm@/gorm?charset=utf8&parseTime=True")
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// db, err = Open("sqlite3", "/tmp/gorm.db")
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// Set the maximum idle database connections
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db.SetPool(100)
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// By default, table name is plural of struct type, if you like singular table name
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db.SingularTable(true)
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// Gorm is goroutines friendly, so you can create a global variable to keep the connection and use it everywhere like this
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var DB gorm.DB
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func init() {
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DB, err = gorm.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
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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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```
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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 update to date.
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FYI, AutoMigrate will only add new columns, won't change column's type or delete unused columns, to make sure gorm won't harm your data.
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If table doesn't exist when AutoMigrate, it will run create table automatically.
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(only postgres and mysql supported)
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```go
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db.AutoMigrate(User{})
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```
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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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```
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### Create With SubStruct
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Refer [Query With Related](#query-with-related) to find 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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Email: []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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//// 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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```
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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` are guessed from the out struct type.
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// You are possible to specify the table name with Model() if no out struct for some methods like Pluck()
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// Or set table name with Table(), if so, it will ignore the out struct even have it. more details following.
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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 a record without order by primary key
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db.Find(&user)
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//// SELECT * FROM users LIMIT 1;
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// Get first record as map
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db.First(&users)
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//// SELECT * FROM users 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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// Using a 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 like condition)
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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 Key
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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 Key
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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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// Normal 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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// 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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// Normal SQL
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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 emails from user 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 address from user 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 the value of user's BillingAddressId
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// Find user from email with guessed primary key value from emails
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db.Model(&email).Related(&user)
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//// SELECT * FROM users WHERE id = 111; // 111 is the value of 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 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 an existing struct's name if name is different
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db.Model(&user).Update("name", "hello")
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//// UPDATE users SET name='hello' WHERE id=111;
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// Find out a struct, and update it if name is different
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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' WHERE id=111;
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// Specify table name with where search
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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 an existing record if have any changed values
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db.Model(&user).Updates(User{Name: "hello", Age: 18})
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//// UPDATE users SET name='hello', age=18 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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## Delete
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### Delete an existing struct
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```go
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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 with search
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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 a struct has DeletedAt field, it will get soft delete ability automatically!
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For those don't have the filed, will be deleted from database permanently
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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 when search
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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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// For structs have DeletedAt field, when do query, will ignore deleted records by default
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db.Where("age = 20").Find(&user)
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//// SELECT * FROM users WHERE age = 100 AND (deleted_at IS NULL AND deleted_at <= '0001-01-02');
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// Find out all records including those deleted 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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// Permanently delete a record 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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## FirstOrInit
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Try to load the first record, if fails, initialize struct with search conditions.
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(only support map or struct conditions, SQL like conditions are not supported)
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```go
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db.FirstOrInit(&user, User{Name: "non_existing"})
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//// User{Name: "non_existing"}
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db.Where(User{Name: "Jinzhu"}).FirstOrInit(&user)
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//// User{Id: 111, Name: "Jinzhu", Age: 20}
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db.FirstOrInit(&user, map[string]interface{}{"name": "jinzhu"})
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//// User{Id: 111, Name: "Jinzhu", Age: 20}
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```
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### FirstOrInit With Attrs
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Attr's arguments would be used to initialize struct if no record found, but won't be used for search
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```go
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db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrInit(&user)
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//// SELECT * FROM USERS WHERE name = 'non_existing';
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//// User{Name: "non_existing", Age: 20}
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// Above code could be simplified if has only one attribute
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db.Where(User{Name: "noexisting_user"}).Attrs("age", 20).FirstOrInit(&user)
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// If a record found, Attrs would be just ignored
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db.Where(User{Name: "Jinzhu"}).Attrs(User{Age: 30}).FirstOrInit(&user)
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//// SELECT * FROM USERS WHERE name = jinzhu';
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//// User{Id: 111, Name: "Jinzhu", Age: 20}
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```
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### FirstOrInit With Assign
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Assign's arguments would be used to set the struct even a record found, but won't be used for search
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```go
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db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrInit(&user)
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//// User{Name: "non_existing", Age: 20}
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db.Where(User{Name: "Jinzhu"}).Assign(User{Age: 30}).FirstOrInit(&user)
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//// User{Id: 111, Name: "Jinzhu", Age: 30}
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```
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## FirstOrCreate
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Try to load the first record, if fails, initialize struct with search conditions and save it
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```go
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db.FirstOrCreate(&user, User{Name: "non_existing"})
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//// User{Id: 112, Name: "non_existing"}
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db.Where(User{Name: "Jinzhu"}).FirstOrCreate(&user)
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//// User{Id: 111, Name: "Jinzhu"}
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db.FirstOrCreate(&user, map[string]interface{}{"name": "jinzhu", "age": 30})
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//// user -> User{Id: 111, Name: "jinzhu", Age: 20}
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```
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### FirstOrCreate With Attrs
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Attr's arguments would be used to initialize struct if no record found, but won't be used for search
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```go
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db.Where(User{Name: "non_existing"}).Attrs(User{Age: 20}).FirstOrCreate(&user)
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//// SELECT * FROM users WHERE name = 'non_existing';
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//// User{Id: 112, Name: "non_existing", Age: 20}
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db.Where(User{Name: "jinzhu"}).Attrs(User{Age: 30}).FirstOrCreate(&user)
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//// User{Id: 111, Name: "jinzhu", Age: 20}
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```
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### FirstOrCreate With Assign
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Assign's arguments would be used to initialize the struct if not record found,
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If any record found, will assign those values to the record, and save it back to database.
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```go
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db.Where(User{Name: "non_existing"}).Assign(User{Age: 20}).FirstOrCreate(&user)
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//// user -> User{Id: 112, Name: "non_existing", Age: 20}
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db.Where(User{Name: "jinzhu"}).Assign(User{Age: 30}).FirstOrCreate(&user)
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//// SELECT * FROM users WHERE name = 'jinzhu';
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//// UPDATE users SET age=30 WHERE id = 111;
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//// User{Id: 111, Name: "jinzhu", Age: 30}
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```
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## Select
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```go
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db.Select("name, age").Find(&users)
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//// SELECT name, age FROM users;
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```
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## Order
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```go
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db.Order("age desc, name").Find(&users)
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//// SELECT * FROM users ORDER BY age desc, name;
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db.Order("age desc").Order("name").Find(&users)
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//// SELECT * FROM users ORDER BY age desc, name;
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// ReOrder
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db.Order("age desc").Find(&users1).Order("age", true).Find(&users2)
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//// SELECT * FROM users ORDER BY age desc; (users1)
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//// SELECT * FROM users ORDER BY age; (users2)
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```
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## Limit
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```go
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db.Limit(3).Find(&users)
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//// SELECT * FROM users LIMIT 3;
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// Cleanup limit with -1
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db.Limit(10).Find(&users1).Limit(-1).Find(&users2)
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//// SELECT * FROM users LIMIT 10; (users1)
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//// SELECT * FROM users; (users2)
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```
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## Offset
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```go
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db.Offset(3).Find(&users)
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//// SELECT * FROM users OFFSET 3;
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// Cleanup offset with -1
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db.Offset(10).Find(&users1).Offset(-1).Find(&users2)
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//// SELECT * FROM users OFFSET 10; (users1)
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//// SELECT * FROM users; (users2)
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```
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## Count
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```go
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db.Where("name = ?", "jinzhu").Or("name = ?", "jinzhu 2").Find(&users).Count(&count)
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//// SELECT * from USERS WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (users)
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//// SELECT count(*) FROM users WHERE name = 'jinzhu' OR name = 'jinzhu 2'; (count)
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|
|
|
// 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 attribute as 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;
|
|
```
|
|
|
|
## Callbacks
|
|
|
|
Callback is a function defined to a struct, the function would be run when reflect a struct to database.
|
|
If the function return an error, will prevent following operations. (for example, stop inserting, updating)
|
|
|
|
Those callbacks are defined now:
|
|
|
|
`BeforeCreate`, `AfterCreate`
|
|
`BeforeUpdate`, `AfterUpdate`
|
|
`BeforeSave`, `AfterSave`
|
|
`BeforeDelete`, `AfterDelete`
|
|
|
|
```go
|
|
func (u *User) BeforeUpdate() (err error) {
|
|
if u.readonly() {
|
|
err = errors.New("Read Only User")
|
|
}
|
|
return
|
|
}
|
|
```
|
|
|
|
## Specify Table Name
|
|
|
|
```go
|
|
// When Create Table from struct
|
|
db.Table("deleted_users").CreateTable(&User{})
|
|
|
|
// When Pluck
|
|
db.Table("users").Pluck("age", &ages)
|
|
//// SELECT age FROM users;
|
|
|
|
// When Query
|
|
var deleted_users []User
|
|
db.Table("deleted_users").Find(&deleted_users)
|
|
//// SELECT * FROM deleted_users;
|
|
|
|
// When Delete
|
|
db.Table("deleted_users").Where("name = ?", "jinzhu").Delete()
|
|
//// DELETE FROM deleted_users WHERE name = 'jinzhu';
|
|
```
|
|
|
|
### Specify Table Name for Struct
|
|
|
|
You are possible to specify table name for a struct by defining method 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"
|
|
}
|
|
}
|
|
```
|
|
|
|
## Run Raw SQl
|
|
|
|
```go
|
|
db.Exec("drop table users;")
|
|
```
|
|
|
|
## Error Handling
|
|
|
|
```go
|
|
query := db.Where("name = ?", "jinzhu").First(&user)
|
|
query := db.First(&user).Limit(10).Find(&users)
|
|
//// query.Error keep the latest error happened
|
|
//// query.Errors keep all errors happened
|
|
//// If an error happened, gorm will stop do query, insert, update, delete
|
|
|
|
// I often use below code to do error handling in real applicatoins
|
|
err = db.Where("name = ?", "jinzhu").First(&user).Error
|
|
```
|
|
|
|
## Advanced Usage With Query Chain
|
|
|
|
Already excited about above usage? 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; (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)
|
|
|
|
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)
|
|
// Do you noticed the table is different?
|
|
|
|
db.Where("mail_type = ?", "TEXT").Find(&users1).Table("deleted_users").First(&user2)
|
|
//// SELECT * FROM users WHERE mail_type = 'TEXT'; (users1)
|
|
//// SELECT * FROM deleted_users WHERE mail_type = 'TEXT'; (users2)
|
|
|
|
db.Where("email = ?", "x@example.org").Attrs(User{FromIp: "111.111.111.111"}).FirstOrCreate(&user)
|
|
//// SELECT * FROM users WHERE email = 'x@example.org';
|
|
//// INSERT INTO "users" (email,from_ip) VALUES ("x@example.org", "111.111.111.111") (if no record found)
|
|
|
|
// Open your mind, add more cool examples
|
|
```
|
|
|
|
## TODO
|
|
* Index, Unique, Valiations
|
|
* SQL Log
|
|
* SQL Query with goroutines
|
|
|
|
# Author
|
|
|
|
**jinzhu**
|
|
|
|
* <http://github.com/jinzhu>
|
|
* <wosmvp@gmail.com>
|
|
* <http://twitter.com/zhangjinzhu>
|