关于golang:聊聊gorm的Unscoped

序

本文次要钻研一下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办法设置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办法在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为指定的工夫戳

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办法设置tx.Statement.Unscoped为true；针对软删除会追加SoftDeleteDeleteClause，即设置deleted_at为指定的工夫戳；而callbacks的Delete办法在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