add test and remove unused warn log (#886)

engine_cond.go

@@ -9,6 +9,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"reflect"
+	"strings"
 	"time"
 
 	"github.com/go-xorm/builder"
@@ -51,7 +52,9 @@ func (engine *Engine) buildConds(table *core.Table, bean interface{},
 
 		fieldValuePtr, err := col.ValueOf(bean)
 		if err != nil {
-			engine.logger.Error(err)
+			if !strings.Contains(err.Error(), "is not valid") {
+				engine.logger.Warn(err)
+			}
 			continue
 		}
 

error.go

@@ -6,6 +6,7 @@ package xorm
 
 import (
 	"errors"
+	"fmt"
 )
 
 var (
@@ -25,4 +26,16 @@ var (
 	ErrNotImplemented = errors.New("Not implemented")
 	// ErrConditionType condition type unsupported
 	ErrConditionType = errors.New("Unsupported conditon type")
+	// ErrColumnIsNotExist columns is not exist
+	ErrFieldIsNotExist = errors.New("Field is not exist")
 )
+
+// ErrFieldIsNotValid is not valid
+type ErrFieldIsNotValid struct {
+	FieldName string
+	TableName string
+}
+
+func (e ErrFieldIsNotValid) Error() string {
+	return fmt.Sprintf("field %s is not valid on table %s", e.FieldName, e.TableName)
+}

interface.go

@@ -42,6 +42,7 @@ type Interface interface {
 	IsTableExist(beanOrTableName interface{}) (bool, error)
 	Iterate(interface{}, IterFunc) error
 	Limit(int, ...int) *Session
+	MustCols(columns ...string) *Session
 	NoAutoCondition(...bool) *Session
 	NotIn(string, ...interface{}) *Session
 	Join(joinOperator string, tablename interface{}, condition string, args ...interface{}) *Session