udf test

test.go

type Fuck struct {
	expression.BaseFunctionClass
}

func (c *Fuck) GetFunction(ctx sessionctx.Context, args []expression.Expression) (expression.BuiltinFunc, error) {
	bf := expression.NewBaseBuiltinFuncWithTp(ctx, args, types.ETString, types.ETString)
	argType := args[0].GetType()
	bf.Tp.Flen = argType.Flen
	expression.SetBinFlagOrBinStr(argType, bf.Tp)
	sig := &BuiltinTrim1ArgSig{bf}
	//sig.SetPbCode(ScalarFuncSig_Trim1Arg)
	return sig, nil
}

type BuiltinTrim1ArgSig struct {
	expression.BaseBuiltinFunc
}

func (b *BuiltinTrim1ArgSig) Clone() expression.BuiltinFunc {
	newSig := &BuiltinTrim1ArgSig{}
	newSig.CloneFrom(&b.BaseBuiltinFunc)
	return newSig
}

const spaceChars = " "

// evalString evals a builtinTrim1ArgSig, corresponding to trim(str)
// See https://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_trim
func (b *BuiltinTrim1ArgSig) evalString(row chunk.Row) (d string, isNull bool, err error) {
	d, isNull, err = b.Args[0].EvalString(b.Ctx, row)
	if isNull || err != nil {
		return d, isNull, err
	}
	return strings.Trim(d, spaceChars), false, nil
}

func (s *testRangerSuite) TestUserDefineMethod(c *C) {
	defer testleak.AfterTest(c)()
	expression.AddUserDefinedFunction("fuck", &Fuck{expression.BaseFunctionClass{"fuck", 1, 1}})
	dom, store, err := newDomainStoreWithBootstrap(c)
	defer func() {
		dom.Close()
		store.Close()
	}()
	c.Assert(err, IsNil)
	testKit := testkit.NewTestKit(c, store)
	testKit.MustExec("use test")
	testKit.MustExec("drop table if exists t")
	testKit.MustExec("create table t(a int primary key, b int, c int, d int, e int, index idx(b,c,d))")
	testKit.MustExec("insert into t values(1,1,1,1,2),(2,1,2,1,0)")
	testKit.MustExec("analyze table t")
	result := testKit.MustQuery(`select fuck(a) from t;`)
	result.Check(testkit.Rows(`ffff`))
}