聊聊gorm的Unscopedgorm的Unscoped方法设置tx.Statement.Unscoped为true；针

序

本文主要研究一下gorm的Unscoped

Unscoped

gorm.io/gorm@v1.20.11/chainable_api.go

func (db *DB) Unscoped() (tx *DB) {
	tx = db.getInstance()
	tx.Statement.Unscoped = true
	return
}

Unscoped方法设置tx.Statement.Unscoped为true

Delete

gorm.io/gorm@v1.20.11/callbacks/delete.go

func Delete(db *gorm.DB) {
	if db.Error == nil {
		if db.Statement.Schema != nil && !db.Statement.Unscoped {
			for _, c := range db.Statement.Schema.DeleteClauses {
				db.Statement.AddClause(c)
			}
		}

		if db.Statement.SQL.String() == "" {
			db.Statement.SQL.Grow(100)
			db.Statement.AddClauseIfNotExists(clause.Delete{})

			if db.Statement.Schema != nil {
				_, queryValues := schema.GetIdentityFieldValuesMap(db.Statement.ReflectValue, db.Statement.Schema.PrimaryFields)
				column, values := schema.ToQueryValues(db.Statement.Table, db.Statement.Schema.PrimaryFieldDBNames, queryValues)

				if len(values) > 0 {
					db.Statement.AddClause(clause.Where{Exprs: []clause.Expression{clause.IN{Column: column, Values: values}}})
				}

				if db.Statement.ReflectValue.CanAddr() && db.Statement.Dest != db.Statement.Model && db.Statement.Model != nil {
					_, queryValues = schema.GetIdentityFieldValuesMap(reflect.ValueOf(db.Statement.Model), db.Statement.Schema.PrimaryFields)
					column, values = schema.ToQueryValues(db.Statement.Table, db.Statement.Schema.PrimaryFieldDBNames, queryValues)

					if len(values) > 0 {
						db.Statement.AddClause(clause.Where{Exprs: []clause.Expression{clause.IN{Column: column, Values: values}}})
					}
				}
			}

			db.Statement.AddClauseIfNotExists(clause.From{})
			db.Statement.Build("DELETE", "FROM", "WHERE")
		}

		if _, ok := db.Statement.Clauses["WHERE"]; !db.AllowGlobalUpdate && !ok && db.Error == nil {
			db.AddError(gorm.ErrMissingWhereClause)
			return
		}

		if !db.DryRun && db.Error == nil {
			result, err := db.Statement.ConnPool.ExecContext(db.Statement.Context, db.Statement.SQL.String(), db.Statement.Vars...)

			if err == nil {
				db.RowsAffected, _ = result.RowsAffected()
			} else {
				db.AddError(err)
			}
		}
	}
}

callbacks的Delete方法在db.Statement.Unscoped为false的时候才追加db.Statement.Schema.DeleteClauses

DeleteClauses

gorm.io/gorm@v1.20.11/soft_delete.go

func (DeletedAt) DeleteClauses(f *schema.Field) []clause.Interface {
	return []clause.Interface{SoftDeleteDeleteClause{Field: f}}
}

针对带有DeletedAt会执行软删除，其db.Statement.Schema.DeleteClauses为SoftDeleteDeleteClause，即设置deleted_at为指定的时间戳

实例

type DemoEntity struct {
	gorm.Model
	Name string `gorm:"column:name"`
}

func unscopedDemo(db *gorm.DB) {
	if err := db.Debug().Unscoped().Where("id = ?", 5).Delete(&DemoEntity{}).Error; err != nil {
		panic(err)
	}
}

小结

gorm的Unscoped方法设置tx.Statement.Unscoped为true；针对软删除会追加SoftDeleteDeleteClause，即设置deleted_at为指定的时间戳；而callbacks的Delete方法在db.Statement.Unscoped为false的时候才追加db.Statement.Schema.DeleteClauses，而Unscoped则执行的是物理删除。

doc

gorm