【转】数据库无关的GO语言ORM

项目地址：https://github.com/eaigner/hood

这是一个极具美感的ORM库。

特性

• 链式的api
• 事务支持
• 迁移和名字空间生成
• 模型变量
• 模型时间
• 数据库方言接口
• 没有含糊的字段
• 干净可测试的代码

打开数据库

如果方言已经注册可以直接打开数据库

hd, err := hood.Open("postgres", "user=<username> dbname=<database>")

你也可以打开数据库时候指定方言

	
hd := hood.New(db, NewPostgres())

Schemas

你可以这样声明

type Person struct {
  
// Auto-incrementing int field 'id'
  Id hood.Id
 
  
// Custom primary key field 'first_name', with presence validation
  FirstName string `sql:"pk" validate:"presence"`
 
  
// string field 'last_name' with size 128, NOT NULL
  LastName string `sql:"size(128),notnull"`
 
  
// string field 'tag' with size 255, default value 'customer'
  Tag string `sql:"size(255),default('customer')"`
 
  
// You can also combine tags, default value 'orange'
  CombinedTags string `sql:"size(128),default('orange')"`
  Birthday     time.Time   
// timestamp field 'birthday'
  Data         []byte      
// data field 'data'
  IsAdmin      bool        
// boolean field 'is_admin'
  Notes        string      
// text field 'notes'
 
  
// You can alternatively define a var char as a string field by setting a size
  Nick  string  `sql:"size(128)"`
 
  
// Validates number range
  Balance int `validate:"range(10:20)"`
 
  
// These fields are auto updated on save
  Created hood.Created
  Updated hood.Updated
 
  
// ... and other built in types (int, uint, float...)
}
 
// Indexes are defined via the Indexed interface to avoid
// polluting the table fields.
 
func (table *Person) Indexes(indexes *hood.Indexes) {
  indexes.Add("tag_index", "tag")
// params: indexName, unique, columns...
  indexes.AddUnique("name_index", "first_name", "last_name")
}

数据迁移

你要先安装hood tool ，然后运行

go get github.com/eaigner/hood
cd $GOPATH/src/github.com/eaigner/hood
./install.sh<

例子

下面是一个使用例子

package main
 
import (
    "hood"
)
 
func main() {
    
// Open a DB connection, use New() alternatively for unregistered dialects
    hd, err := hood.Open("postgres", "user=hood dbname=hood_test sslmode=disable")
    if err != nil {
        panic(err)
    }
 
    
// Create a table
    type Fruit struct {
        Id    hood.Id
        Name  string `validate:"presence"`
        Color string
    }
 
    err = hd.CreateTable(&Fruit{})
    if err != nil {
        panic(err)
    }
 
    fruits := []Fruit{
        Fruit{Name: "banana", Color: "yellow"},
        Fruit{Name: "apple", Color: "red"},
        Fruit{Name: "grapefruit", Color: "yellow"},
        Fruit{Name: "grape", Color: "green"},
        Fruit{Name: "pear", Color: "yellow"},
    }
 
    
// Start a transaction
    tx := hd.Begin()
 
    ids, err := tx.SaveAll(&fruits)
    if err != nil {
        panic(err)
    }
 
    fmt.Println("inserted ids:", ids)
// [1 2 3 4 5]
 
    
// Commit changes
    err = tx.Commit()
    if err != nil {
        panic(err)
    }
 
    
// Ids are automatically updated
    if fruits[0].Id != 1 || fruits[1].Id != 2 || fruits[2].Id != 3 {
        panic("id not set")
    }
 
    
// If an id is already set, a call to save will result in an update
    fruits[0].Color = "green"
 
    ids, err = hd.SaveAll(&fruits)
    if err != nil {
        panic(err)
    }
 
    fmt.Println("updated ids:", ids)
// [1 2 3 4 5]
 
    if fruits[0].Id != 1 || fruits[1].Id != 2 || fruits[2].Id != 3 {
        panic("id not set")
    }
 
    
// Let's try to save a row that does not satisfy the required validations
    _, err = hd.Save(&Fruit{})
    if err == nil || err.Error() != "value not set" {
        panic("does not satisfy validations, should not save")
    }
 
    
// Find
    
//
    
// The markers are db agnostic, so you can always use '?'
    
// e.g. in Postgres they are replaced with $1, $2, ...
    var results []Fruit
    err = hd.Where("color", "=", "green").OrderBy("name").Limit(1).Find(&results)
    if err != nil {
        panic(err)
    }
 
    fmt.Println("results:", results)
// [{1 banana green}]
 
    
// Delete
    ids, err = hd.DeleteAll(&results)
    if err != nil {
        panic(err)
    }
 
    fmt.Println("deleted ids:", ids)
// [1]
 
    results = nil
    err = hd.Find(&results)
    if err != nil {
        panic(err)
    }
 
    fmt.Println("results:", results)
// [{2 apple red} {3 grapefruit yellow} {4 grape green} {5 pear yellow}]
 
    
// Drop
    hd.DropTable(&Fruit{})
}