go gorm 查询

1. 定义model

package mysqltestimport ("errors""fmt""gorm.io/gorm"
)type Product struct {gorm.ModelID    uint    `gorm:"primarykey"`Name  string  `gorm:"column:name"`Price float64 `gorm:"column:price_value"`Test  string  `gorm:"-"`
}type Tabler interface {TableName() string
}// 修改表名
func (recv Product) TableName() string {return "product"
}// 钩子
func (recv *Product) BeforeCreate(tx *gorm.DB) (err error) {if recv.Name == "haha" {fmt.Println("不合法哈")return errors.New("不合法哈")} else {return nil}
}

2. helper

package mysqltestimport ("fmt""gorm.io/driver/mysql""gorm.io/gorm""gorm.io/gorm/clause"
)var db *gorm.DBfunc Initdb() {dsn := "ellis:ellis@tcp(192.168.214.134:3306)/go_db?charset=utf8mb4&parseTime=True&loc=Local"var err errordb, err = gorm.Open(mysql.Open(dsn), &gorm.Config{})if err != nil {panic(err)}
}func Create(value interface{}) {d := db.Create(value)fmt.Printf("d.RowsAffected: %v\n", d.RowsAffected)
}func InitTable(table interface{}) {db.AutoMigrate(table)
}// 根据选择的字段插入
func CreateBySelectFields(fields []string, value interface{}) {db.Select(fields).Create(value)
}// 批量插入
func CreateMulti(value interface{}) {d := db.Create(value)fmt.Printf("d.RowsAffected: %v\n", d.RowsAffected)
}// 批量插入
func CreateBatch(value interface{}) {d := db.CreateInBatches(value, 100)fmt.Printf("d.RowsAffected: %v\n", d.RowsAffected)
}// 忽略钩子
func CreateIgnoreHook(value interface{}) {db.Session(&gorm.Session{SkipHooks: true}).Create(value)
}// 通过map创建
func CreateByMap(value map[string]interface{}, model interface{}) {db.Model(model).Create(value)
}// 冲突啥也不做
func DoNothingWhenInsert(value interface{}) {db.Clauses(clause.OnConflict{DoNothing: true}).Create(value)
}// 通过主键查找
func FindByKey(value interface{}) {db.Find(value, 1)
}// 查找后映射到map类型
func FindAndConvertToMap(value interface{}, result *map[string]interface{}) {db.Model(value).First(result)
}// 多主键查找
func FindByMultiKey(value interface{}, keys []int) {db.Find(value, keys)
}// 条件查找
func FindByCondition(value interface{}) {db.Where("name=?", "haha").Order("id desc").Find((value))
}// struct 查找，会忽略0值，例如传入ID=0，这个ID=0不会作为查询条件
func FindByStruct(value interface{}, condition interface{}) {db.Where(condition).Find(value)
}// 指定结构体查询字段
func FindByStructWithReturnFields(value interface{}, condition interface{}, returnFields ...string) {db.Where(condition, returnFields).Order("id desc").Find(value)
}

3. main

package mainimport ("ellis/mysqltest""fmt"
)func main() {mysqltest.Initdb()// 创建数据库mysqltest.InitTable(&mysqltest.Product{})var value mysqltest.Productmysqltest.FindByKey(&value)fmt.Printf("value: %v\n", value)// 映射到mapresult := map[string]interface{}{}mysqltest.FindAndConvertToMap(mysqltest.Product{}, &result)fmt.Printf("result: %v\n", result)// 多主键查找var products1 []mysqltest.Productmysqltest.FindByMultiKey(&products1, []int{1, 2, 3})for _, v := range products1 {fmt.Printf("v: %v\n", v)}// 条件查找var products2 []mysqltest.Productmysqltest.FindByCondition(&products2)for _, v := range products2 {fmt.Printf("v: %v\n", v)}// struct 查找var products3 []mysqltest.Product// ID 为0的被忽略produce := mysqltest.Product{Name: "haha", ID: 0}mysqltest.FindByStruct(&products3, produce)for _, v := range products3 {fmt.Printf("v: %v\n", v)}// map 查找var products4 []mysqltest.Product// ID 为0的被忽略produce1 := map[string]interface{}{"Name": "haha", "ID": 0}mysqltest.FindByStruct(&products4, produce1)for _, v := range products4 {fmt.Printf("v: %v\n", v)}// struct 查找，可以设置使用的struct的keyvar products []mysqltest.Product// ID 为0的被忽略produce2 := mysqltest.Product{Name: "haha"}mysqltest.FindByStructWithReturnFields(&products, produce2, "name", "id")for _, v := range products {fmt.Printf("v: %v\n", v)}
}

https://gorm.io/docs/query.html

https://gorm.io/docs/advanced_query.html