gorm many2many 重新创建数据库中已有的条目
gorm many2many recreate an entry already in database
我目前正在将我的服务更新到 gorm v2 的新版本。
我有一个 many2many 关联的问题，在下面的代码中，我显示了 gorm 执行的 SQL 查询，我看到 grom 做了一个 INSERT （我添加了❗️）因此当他只应该建立关联时，它将重新创建一个已经在数据库中的 Material。
你知道我如何在不重新创建和/或不修改相关元素的情况下只创建关联吗？
package main
import (
"encoding/json"
"fmt"
"log"
"time"
uuid "github.com/google/uuid"
"gorm.io/driver/postgres"
"gorm.io/gorm"
)
type (
// Base model
Base struct {
ID string `gorm:"type:char(36);primaryKey;" json:"id"`
CreatedAt time.Time `json:"created_at" diff:"-"`
UpdatedAt time.Time `json:"update_at" diff:"-"`
DeletedAt *time.Time `sql:"index" json:"deleted_at" diff:"-"`
}
// Project model
Project struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Batches []Batch `json:"batches,string" form:"batches" gorm:"batches;"`
}
// Batch model
Batch struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Project Project `json:"project"`
ProjectID string `json:"project_id" form:"project_id" gorm:"type:char(36);project_id;"`
Materials []Material `json:"materials" gorm:"many2many:batches_materials;association_foreignkey:ID;foreignkey:ID"`
}
// Material model
Material struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Category Category `json:"category"`
CategoryID string `json:"category_id" form:"category_id" gorm:"type:char(36);category_id;"`
Batches []Batch `json:"batches" gorm:"many2many:batches_materials;association_foreignkey:ID;foreignkey:ID"`
}
// Category model
Category struct {
Base
Name string `json:"name" form:"name" gorm:"name;"`
}
)
// BeforeCreate will set a UUID rather than numeric ID.
func (b *Base) BeforeCreate(tx *gorm.DB) (err error) {
uuid := uuid.New()
b.ID = uuid.String()
return
}
func main() {
url := fmt.Sprintf("postgres://%v:%v@%v:%v/%v?sslmode=disable", "postgres", "postgres_docker", "0.0.0.0", "5432", "test_gorm")
db, _ := gorm.Open(postgres.Open(url), &gorm.Config{})
db.Migrator().DropTable(&Batch{}, &Project{}, &Material{}, &Category{})
db.AutoMigrate(&Batch{}, &Project{}, &Material{}, &Category{})
db = db.Debug()
// Create Project
project := Project{
Title: "Project 1",
}
db.Save(&project)
// ✅ INSERT INTO "projects" ("id","created_at","updated_at","deleted_at","title") VALUES ('92db2acd-7d71-41dc-bb28-07a06c25fd79','2020-11-21 07:03:01.61','2020-11-21 07:03:01.61',NULL,'Project 1')
// Create Category
category := Category{
Name: "Category 1",
}
db.Save(&category)
// ✅ INSERT INTO "categories" ("id","created_at","updated_at","deleted_at","name") VALUES ('fdd433f2-9153-4ad8-b4e0-da20f69994c9','2020-11-21 07:03:01.615','2020-11-21 07:03:01.615',NULL,'Category 1')
// Create Material 1
material1 := Material{
Title: "Material 1",
CategoryID: category.ID,
}
db.Save(&material1)
// ✅ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('a8beeac9-1cbb-487a-bdad-50bc70ea6f09','2020-11-21 07:03:01.621','2020-11-21 07:03:01.621',NULL,'Material 1','fdd433f2-9153-4ad8-b4e0-da20f69994c9')
// Create Material 2
material2 := Material{
Title: "Material 2",
CategoryID: category.ID,
}
db.Save(&material2)
// ✅ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('a940ac32-d5e0-4ac8-9f5f-f0bfc54e52ab','2020-11-21 07:03:01.627','2020-11-21 07:03:01.627',NULL,'Material 2','fdd433f2-9153-4ad8-b4e0-da20f69994c9')
// Create Batch
batch := Batch{
Title: "Batch 1",
ProjectID: project.ID,
}
db.Save(&batch)
// ✅ INSERT INTO "batches" ("id","created_at","updated_at","deleted_at","title","project_id") VALUES ('d48546f8-7cc7-4523-8910-72b02744a152','2020-11-21 07:03:01.631','2020-11-21 07:03:01.631',NULL,'Batch 1','92db2acd-7d71-41dc-bb28-07a06c25fd79')
// Now i want to link Materials of batch
// Find Batch
myBatch := Batch{}
db.Where("id = ?", batch.ID).First(&myBatch)
// ✅ SELECT * FROM "batches" WHERE id = 'd48546f8-7cc7-4523-8910-72b02744a152' ORDER BY "batches"."id" LIMIT 1
// Find two Materials
materials := []Material{}
db.Where("id in (?)", []string{material1.ID, material2.ID}).Find(&materials)
// ✅ SELECT * FROM "materials" WHERE id in ('a8beeac9-1cbb-487a-bdad-50bc70ea6f09','a940ac32-d5e0-4ac8-9f5f-f0bfc54e52ab')
// Add two Materials Association for batch model
db.Model(&myBatch).Association("Materials").Replace(&materials)
// ❗️ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('f2629f9d-403f-425d-afc5-074b5e8a0ecc','2020-11-21 07:03:01.621','2020-11-21 07:03:01.621',NULL,'Material 1','fdd433f2-9153-4ad8-b4e0-da20f69994c9'),('d5b709d6-1208-4951-887a-2cfafab75774','2020-11-21 07:03:01.627','2020-11-21 07:03:01.627',NULL,'Material 2','fdd433f2-9153-4ad8-b4e0-da20f69994c9') ON CONFLICT DO NOTHING
// ✅ INSERT INTO "batches_materials" ("batch_id","material_id") VALUES ('d48546f8-7cc7-4523-8910-72b02744a152','f2629f9d-403f-425d-afc5-074b5e8a0ecc'),('d48546f8-7cc7-4523-8910-72b02744a152','d5b709d6-1208-4951-887a-2cfafab75774') ON CONFLICT DO NOTHING
// ✅ DELETE FROM "batches_materials" WHERE "batches_materials"."batch_id" = 'd48546f8-7cc7-4523-8910-72b02744a152' AND "batches_materials"."material_id" NOT IN ('f2629f9d-403f-425d-afc5-074b5e8a0ecc','d5b709d6-1208-4951-887a-2cfafab75774')
d, _ := json.MarshalIndent(batch, " ", "\t")
log.Println(string(d))
}
我以 BeforeCreate.
为代价，使用具有 gen_random_uuid() 的本机 PostgreSQL 函数的潜力解决了这个问题
type Base struct {
ID string `json:"id" gorm:"type:uuid;primaryKey;default:gen_random_uuid()"` // <-- like this
CreatedAt time.Time `json:"created_at" diff:"-"`
UpdatedAt time.Time `json:"update_at" diff:"-"`
DeletedAt *time.Time `sql:"index" json:"deleted_at" diff:"-"`
Displayname string `json:"displayname" gorm:"displayname;" diff:"-"`
}
我目前正在将我的服务更新到 gorm v2 的新版本。
我有一个 many2many 关联的问题，在下面的代码中，我显示了 gorm 执行的 SQL 查询，我看到 grom 做了一个 INSERT （我添加了❗️）因此当他只应该建立关联时，它将重新创建一个已经在数据库中的 Material。
你知道我如何在不重新创建和/或不修改相关元素的情况下只创建关联吗？
package main
import (
"encoding/json"
"fmt"
"log"
"time"
uuid "github.com/google/uuid"
"gorm.io/driver/postgres"
"gorm.io/gorm"
)
type (
// Base model
Base struct {
ID string `gorm:"type:char(36);primaryKey;" json:"id"`
CreatedAt time.Time `json:"created_at" diff:"-"`
UpdatedAt time.Time `json:"update_at" diff:"-"`
DeletedAt *time.Time `sql:"index" json:"deleted_at" diff:"-"`
}
// Project model
Project struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Batches []Batch `json:"batches,string" form:"batches" gorm:"batches;"`
}
// Batch model
Batch struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Project Project `json:"project"`
ProjectID string `json:"project_id" form:"project_id" gorm:"type:char(36);project_id;"`
Materials []Material `json:"materials" gorm:"many2many:batches_materials;association_foreignkey:ID;foreignkey:ID"`
}
// Material model
Material struct {
Base
Title string `json:"title" form:"title" gorm:"title;"`
Category Category `json:"category"`
CategoryID string `json:"category_id" form:"category_id" gorm:"type:char(36);category_id;"`
Batches []Batch `json:"batches" gorm:"many2many:batches_materials;association_foreignkey:ID;foreignkey:ID"`
}
// Category model
Category struct {
Base
Name string `json:"name" form:"name" gorm:"name;"`
}
)
// BeforeCreate will set a UUID rather than numeric ID.
func (b *Base) BeforeCreate(tx *gorm.DB) (err error) {
uuid := uuid.New()
b.ID = uuid.String()
return
}
func main() {
url := fmt.Sprintf("postgres://%v:%v@%v:%v/%v?sslmode=disable", "postgres", "postgres_docker", "0.0.0.0", "5432", "test_gorm")
db, _ := gorm.Open(postgres.Open(url), &gorm.Config{})
db.Migrator().DropTable(&Batch{}, &Project{}, &Material{}, &Category{})
db.AutoMigrate(&Batch{}, &Project{}, &Material{}, &Category{})
db = db.Debug()
// Create Project
project := Project{
Title: "Project 1",
}
db.Save(&project)
// ✅ INSERT INTO "projects" ("id","created_at","updated_at","deleted_at","title") VALUES ('92db2acd-7d71-41dc-bb28-07a06c25fd79','2020-11-21 07:03:01.61','2020-11-21 07:03:01.61',NULL,'Project 1')
// Create Category
category := Category{
Name: "Category 1",
}
db.Save(&category)
// ✅ INSERT INTO "categories" ("id","created_at","updated_at","deleted_at","name") VALUES ('fdd433f2-9153-4ad8-b4e0-da20f69994c9','2020-11-21 07:03:01.615','2020-11-21 07:03:01.615',NULL,'Category 1')
// Create Material 1
material1 := Material{
Title: "Material 1",
CategoryID: category.ID,
}
db.Save(&material1)
// ✅ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('a8beeac9-1cbb-487a-bdad-50bc70ea6f09','2020-11-21 07:03:01.621','2020-11-21 07:03:01.621',NULL,'Material 1','fdd433f2-9153-4ad8-b4e0-da20f69994c9')
// Create Material 2
material2 := Material{
Title: "Material 2",
CategoryID: category.ID,
}
db.Save(&material2)
// ✅ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('a940ac32-d5e0-4ac8-9f5f-f0bfc54e52ab','2020-11-21 07:03:01.627','2020-11-21 07:03:01.627',NULL,'Material 2','fdd433f2-9153-4ad8-b4e0-da20f69994c9')
// Create Batch
batch := Batch{
Title: "Batch 1",
ProjectID: project.ID,
}
db.Save(&batch)
// ✅ INSERT INTO "batches" ("id","created_at","updated_at","deleted_at","title","project_id") VALUES ('d48546f8-7cc7-4523-8910-72b02744a152','2020-11-21 07:03:01.631','2020-11-21 07:03:01.631',NULL,'Batch 1','92db2acd-7d71-41dc-bb28-07a06c25fd79')
// Now i want to link Materials of batch
// Find Batch
myBatch := Batch{}
db.Where("id = ?", batch.ID).First(&myBatch)
// ✅ SELECT * FROM "batches" WHERE id = 'd48546f8-7cc7-4523-8910-72b02744a152' ORDER BY "batches"."id" LIMIT 1
// Find two Materials
materials := []Material{}
db.Where("id in (?)", []string{material1.ID, material2.ID}).Find(&materials)
// ✅ SELECT * FROM "materials" WHERE id in ('a8beeac9-1cbb-487a-bdad-50bc70ea6f09','a940ac32-d5e0-4ac8-9f5f-f0bfc54e52ab')
// Add two Materials Association for batch model
db.Model(&myBatch).Association("Materials").Replace(&materials)
// ❗️ INSERT INTO "materials" ("id","created_at","updated_at","deleted_at","title","category_id") VALUES ('f2629f9d-403f-425d-afc5-074b5e8a0ecc','2020-11-21 07:03:01.621','2020-11-21 07:03:01.621',NULL,'Material 1','fdd433f2-9153-4ad8-b4e0-da20f69994c9'),('d5b709d6-1208-4951-887a-2cfafab75774','2020-11-21 07:03:01.627','2020-11-21 07:03:01.627',NULL,'Material 2','fdd433f2-9153-4ad8-b4e0-da20f69994c9') ON CONFLICT DO NOTHING
// ✅ INSERT INTO "batches_materials" ("batch_id","material_id") VALUES ('d48546f8-7cc7-4523-8910-72b02744a152','f2629f9d-403f-425d-afc5-074b5e8a0ecc'),('d48546f8-7cc7-4523-8910-72b02744a152','d5b709d6-1208-4951-887a-2cfafab75774') ON CONFLICT DO NOTHING
// ✅ DELETE FROM "batches_materials" WHERE "batches_materials"."batch_id" = 'd48546f8-7cc7-4523-8910-72b02744a152' AND "batches_materials"."material_id" NOT IN ('f2629f9d-403f-425d-afc5-074b5e8a0ecc','d5b709d6-1208-4951-887a-2cfafab75774')
d, _ := json.MarshalIndent(batch, " ", "\t")
log.Println(string(d))
}
我以 BeforeCreate.
gen_random_uuid() 的本机 PostgreSQL 函数的潜力解决了这个问题
type Base struct {
ID string `json:"id" gorm:"type:uuid;primaryKey;default:gen_random_uuid()"` // <-- like this
CreatedAt time.Time `json:"created_at" diff:"-"`
UpdatedAt time.Time `json:"update_at" diff:"-"`
DeletedAt *time.Time `sql:"index" json:"deleted_at" diff:"-"`
Displayname string `json:"displayname" gorm:"displayname;" diff:"-"`
}