chore: improve error msg

Change-Id: I71ef652a8a81dc0874f56e6f64d8c1ecabeaf938

Author: andeya

tagexpr.go

@@ -112,7 +112,7 @@ func (vm *VM) Run(structOrStructPtrOrReflectValue interface{}) (*TagExpr, error)
 		u = tpack.Unpack(structOrStructPtrOrReflectValue)
 	}
 	if u.IsNil() {
-		return nil, errors.New("unsupported nil")
+		return nil, errors.New("unsupport data: nil")
 	}
 	u = u.UnderlyingElem()
 	tid := u.RuntimeTypeID()
@@ -510,7 +510,7 @@ func (vm *VM) getStructType(t reflect.Type) (reflect.Type, error) {
 		structType = structType.Elem()
 	}
 	if structType.Kind() != reflect.Struct {
-		return nil, fmt.Errorf("unsupported %s", t.String())
+		return nil, fmt.Errorf("unsupport type: %s", t.String())
 	}
 	return structType, nil
 }

validator/README.md

@@ -98,16 +98,16 @@ func Example() {
 
 	// Output:
 	// true
-	// validation failed: Email
+	// invalid parameter: Email
 	// true
 	// C must be false when S.A>0
 	// invalid d: [x y]
-	// validation failed: e
+	// invalid parameter: e
 	// {"succ":false, "error":"validation failed: f.g"}
 	// {"succ":false, "error":"validation failed: a/f.g"}
 	// {"succ":false, "error":"validation failed: {k}/f.g"}
 	// {"succ":false, "error":"validation failed: 0/0/f.g"}
-	// validation failed: unsupported nil
+	// unsupport data: nil
 	// <nil>
 	// <nil>
 }

validator/example_test.go

@@ -79,16 +79,16 @@ func Example() {
 
 	// Output:
 	// true
-	// validation failed: Email
+	// invalid parameter: Email
 	// true
 	// C must be false when S.A>0
 	// invalid d: [x y]
-	// validation failed: e
+	// invalid parameter: e
 	// {"succ":false, "error":"validation failed: f.g"}
 	// {"succ":false, "error":"validation failed: a/f.g"}
 	// {"succ":false, "error":"validation failed: {k}/f.g"}
 	// {"succ":false, "error":"validation failed: 0/0/f.g"}
-	// validation failed: unsupported nil
+	// unsupport data: nil
 	// <nil>
 	// <nil>
 }

validator/validator.go

@@ -16,7 +16,6 @@
 package validator
 
 import (
-	"errors"
 	"reflect"
 	"strconv"
 	"strings"
@@ -110,7 +109,7 @@ func (v *Validator) validate(selectorPrefix string, value reflect.Value) error {
 
 	expr, err := v.vm.Run(rv)
 	if err != nil {
-		return errors.New("validation failed: " + err.Error())
+		return err
 	}
 	var errSelector string
 	var valid bool
@@ -147,7 +146,7 @@ func (e *Error) Error() string {
 	if e.Msg != "" {
 		return e.Msg
 	}
-	return "validation failed: " + e.FailPath
+	return "invalid parameter: " + e.FailPath
 }
 
 func defaultErrorFactory(failPath, msg string) error {