func (e *Evaluator) funcConvert(f *ast.FuncConvertExpr) bool {
value := f.Expr.GetValue()
// Casting nil to any type returns nil
if value == nil {
f.SetValue(nil)
return true
}
str, ok := value.(string)
if !ok {
return true
}
if strings.ToLower(f.Charset) == "ascii" {
f.SetValue(value)
return true
} else if strings.ToLower(f.Charset) == "utf8mb4" {
f.SetValue(value)
return true
}
encoding, _ := charset.Lookup(f.Charset)
if encoding == nil {
e.err = ErrInvalidOperation.Gen("unknown encoding: %s", f.Charset)
return false
}
target, _, err := transform.String(encoding.NewDecoder(), str)
if err != nil {
log.Errorf("Convert %s to %s with error: %v", str, f.Charset, err)
e.err = errors.Trace(err)
return false
}
f.SetValue(target)
return true
}
// See https://dev.mysql.com/doc/refman/5.7/en/cast-functions.html#function_convert
func builtinConvert(args []types.Datum, _ context.Context) (d types.Datum, err error) {
// Casting nil to any type returns nil
if args[0].Kind() != types.KindString {
return d, nil
}
str := args[0].GetString()
Charset := args[1].GetString()
if strings.ToLower(Charset) == "ascii" {
d.SetString(str)
return d, nil
} else if strings.ToLower(Charset) == "utf8mb4" {
d.SetString(str)
return d, nil
}
encoding, _ := charset.Lookup(Charset)
if encoding == nil {
return d, errors.Errorf("unknown encoding: %s", Charset)
}
target, _, err := transform.String(encoding.NewDecoder(), str)
if err != nil {
log.Errorf("Convert %s to %s with error: %v", str, Charset, err)
return d, errors.Trace(err)
}
d.SetString(target)
return d, nil
}