Show Gorm Pluck query on JSONType and JSONSlice

show_gorm_pluck_query.go

package main

import (
	"context"
	"database/sql"
	"fmt"

	"gorm.io/datatypes"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

type (
	User struct {
		Name string `json:"name"`
		Age  int    `json:"age"`
	}

	TestTable struct {
		ID     uint64
		Info   datatypes.JSONType[*User]
		Parent datatypes.JSONSlice[*User]
	}
)

func (*TestTable) TableName() string {
	return "user"
}

func main() {
	var ctx = context.Background()
	var db = prepareDB()
	var err error
	db = db.WithContext(ctx)
	db.AutoMigrate(&TestTable{})

	db.Create(&TestTable{
		Info:   datatypes.NewJSONType(&User{Name: "name", Age: 18}),
		Parent: datatypes.JSONSlice[*User]{&User{Name: "A", Age: 38}, &User{Name: "B", Age: 39}},
	})
	// ok
	row := &TestTable{}
	db.Limit(1).Order("id DESC").Find(row)
	// find all row  &{name 18}
	fmt.Println("find all row ", row.Info.Data())

	// ok
	var field []datatypes.JSONType[*User]
	err = db.Model(&TestTable{}).Limit(1).Order("id DESC").Pluck("info", &field).Error
	// find field  &{name 18} <nil>
	fmt.Println("find field ", field[0].Data(), err)

	// ok
	var fullRow TestTable
	err = db.Model(&TestTable{}).Limit(1).Order("id DESC").Pluck("info", &fullRow.Info).Error
	// find field in row  <nil> &{name 18}
	fmt.Println("find field in row ", err, fullRow.Info.Data())

	// ok
	var parents []datatypes.JSONSlice[*User]
	err = db.Model(&TestTable{}).Limit(1).Order("id DESC").Pluck("parent", &parents).Error
	fmt.Println("find parents in slice ", err, parents[0], *parents[0][0], *parents[0][1])
}

func prepareDB() *gorm.DB {
	var err error
	pool, err := sql.Open("mysql", "root:@tcp(localhost:3306)/test?charset=utf8mb4&parseTime=true&loc=Local")
	if err != nil {
		panic(err)
	}
	db, err := gorm.Open(mysql.New(mysql.Config{Conn: pool}), &gorm.Config{})
	if err != nil {
		panic(err)
	}
	return db
}