diff --git a/field.go b/field.go
index 1d20e4d9..4575bd6c 100644
--- a/field.go
+++ b/field.go
@@ -23,13 +23,13 @@ type Field struct {
 }
 
 func (f *Field) IsScanner() bool {
-	_, is_scanner := reflect.New(reflect.ValueOf(f.Value).Type()).Interface().(sql.Scanner)
-	return is_scanner
+	_, isScanner := reflect.New(reflect.ValueOf(f.Value).Type()).Interface().(sql.Scanner)
+	return isScanner
 }
 
 func (f *Field) IsTime() bool {
-	_, is_time := f.Value.(time.Time)
-	return is_time
+	_, isTime := f.Value.(time.Time)
+	return isTime
 }
 
 func parseSqlTag(str string) (typ string, additionalType string, size int) {
diff --git a/scope.go b/scope.go
index 05e45fc7..a77baa14 100644
--- a/scope.go
+++ b/scope.go
@@ -82,7 +82,7 @@ func (scope *Scope) PrimaryKey() string {
 		return scope.primaryKey
 	}
 
-	scope.primaryKey = scope.getPrimaryKey()
+	scope.primaryKey = ToSnake(GetPrimaryKey(scope.Value))
 	return scope.primaryKey
 }
 
diff --git a/scope_private.go b/scope_private.go
index 6298c3d7..0fe406c0 100644
--- a/scope_private.go
+++ b/scope_private.go
@@ -5,7 +5,6 @@ import (
 	"database/sql/driver"
 	"errors"
 	"fmt"
-	"go/ast"
 	"reflect"
 	"regexp"
 	"strconv"
@@ -466,33 +465,3 @@ func (scope *Scope) autoMigrate() *Scope {
 	}
 	return scope
 }
-
-func (scope *Scope) getPrimaryKey() string {
-	var indirectValue reflect.Value
-
-	indirectValue = reflect.Indirect(reflect.ValueOf(scope.Value))
-
-	if indirectValue.Kind() == reflect.Slice {
-		indirectValue = reflect.New(indirectValue.Type().Elem()).Elem()
-	}
-
-	if !indirectValue.IsValid() {
-		return "id"
-	}
-
-	scopeTyp := indirectValue.Type()
-	for i := 0; i < scopeTyp.NumField(); i++ {
-		fieldStruct := scopeTyp.Field(i)
-		if !ast.IsExported(fieldStruct.Name) {
-			continue
-		}
-
-		// if primaryKey tag found, return column name
-		if fieldStruct.Tag.Get("primaryKey") != "" {
-			return ToSnake(fieldStruct.Name)
-		}
-	}
-
-	//If primaryKey tag not found, fallback to id
-	return "id"
-}
diff --git a/utils.go b/utils.go
index a9091aeb..afef469e 100644
--- a/utils.go
+++ b/utils.go
@@ -2,12 +2,8 @@ package gorm
 
 import (
 	"bytes"
-	"database/sql"
-	"fmt"
-	"os"
+	"go/ast"
 	"reflect"
-	"regexp"
-	"runtime"
 	"strings"
 	"sync"
 )
@@ -95,82 +91,26 @@ func SnakeToUpperCamel(s string) string {
 	return u
 }
 
-func toSearchableMap(attrs ...interface{}) (result interface{}) {
-	if len(attrs) > 1 {
-		if str, ok := attrs[0].(string); ok {
-			result = map[string]interface{}{str: attrs[1]}
-		}
-	} else if len(attrs) == 1 {
-		if attr, ok := attrs[0].(map[string]interface{}); ok {
-			result = attr
-		}
+func GetPrimaryKey(value interface{}) string {
+	var indirectValue = reflect.Indirect(reflect.ValueOf(value))
 
-		if attr, ok := attrs[0].(interface{}); ok {
-			result = attr
-		}
+	if indirectValue.Kind() == reflect.Slice {
+		indirectValue = reflect.New(indirectValue.Type().Elem()).Elem()
 	}
-	return
-}
 
-func fileWithLineNum() string {
-	for i := 1; i < 15; i++ {
-		_, file, line, ok := runtime.Caller(i)
-		if ok && (!regexp.MustCompile(`jinzhu/gorm/.*.go`).MatchString(file) || regexp.MustCompile(`jinzhu/gorm/.*test.go`).MatchString(file)) {
-			return fmt.Sprintf("%v:%v", strings.TrimPrefix(file, os.Getenv("GOPATH")+"src/"), line)
-		}
-	}
-	return ""
-}
-
-func setFieldValue(field reflect.Value, value interface{}) (result bool) {
-	result = false
-	if field.IsValid() && field.CanAddr() {
-		result = true
-		if scanner, ok := field.Addr().Interface().(sql.Scanner); ok {
-			scanner.Scan(value)
-		} else if reflect.TypeOf(value).ConvertibleTo(field.Type()) {
-			field.Set(reflect.ValueOf(value).Convert(field.Type()))
-		} else {
-			result = false
-		}
-	}
-	return
-}
-
-func isBlank(value reflect.Value) bool {
-	return reflect.DeepEqual(value.Interface(), reflect.Zero(value.Type()).Interface())
-}
-
-func convertInterfaceToMap(values interface{}) map[string]interface{} {
-	attrs := map[string]interface{}{}
-
-	switch value := values.(type) {
-	case map[string]interface{}:
-		for k, v := range value {
-			attrs[ToSnake(k)] = v
-		}
-	case []interface{}:
-		for _, v := range value {
-			for key, value := range convertInterfaceToMap(v) {
-				attrs[key] = value
+	if indirectValue.IsValid() {
+		scopeTyp := indirectValue.Type()
+		for i := 0; i < scopeTyp.NumField(); i++ {
+			fieldStruct := scopeTyp.Field(i)
+			if !ast.IsExported(fieldStruct.Name) {
+				continue
 			}
-		}
-	case interface{}:
-		reflectValue := reflect.ValueOf(values)
 
-		switch reflectValue.Kind() {
-		case reflect.Map:
-			for _, key := range reflectValue.MapKeys() {
-				attrs[ToSnake(key.Interface().(string))] = reflectValue.MapIndex(key).Interface()
-			}
-		default:
-			scope := Scope{Value: values}
-			for _, field := range scope.Fields() {
-				if !field.IsBlank {
-					attrs[field.DBName] = field.Value
-				}
+			if fieldStruct.Tag.Get("primaryKey") != "" {
+				return fieldStruct.Name
 			}
 		}
 	}
-	return attrs
+
+	return "Id"
 }
diff --git a/utils_private.go b/utils_private.go
new file mode 100644
index 00000000..75c38fcd
--- /dev/null
+++ b/utils_private.go
@@ -0,0 +1,91 @@
+package gorm
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"reflect"
+	"regexp"
+	"runtime"
+	"strings"
+)
+
+func fileWithLineNum() string {
+	for i := 1; i < 15; i++ {
+		_, file, line, ok := runtime.Caller(i)
+		if ok && (!regexp.MustCompile(`jinzhu/gorm/.*.go`).MatchString(file) || regexp.MustCompile(`jinzhu/gorm/.*test.go`).MatchString(file)) {
+			return fmt.Sprintf("%v:%v", strings.TrimPrefix(file, os.Getenv("GOPATH")+"src/"), line)
+		}
+	}
+	return ""
+}
+
+func setFieldValue(field reflect.Value, value interface{}) (result bool) {
+	result = false
+	if field.IsValid() && field.CanAddr() {
+		result = true
+		if scanner, ok := field.Addr().Interface().(sql.Scanner); ok {
+			scanner.Scan(value)
+		} else if reflect.TypeOf(value).ConvertibleTo(field.Type()) {
+			field.Set(reflect.ValueOf(value).Convert(field.Type()))
+		} else {
+			result = false
+		}
+	}
+	return
+}
+
+func isBlank(value reflect.Value) bool {
+	return reflect.DeepEqual(value.Interface(), reflect.Zero(value.Type()).Interface())
+}
+
+func toSearchableMap(attrs ...interface{}) (result interface{}) {
+	if len(attrs) > 1 {
+		if str, ok := attrs[0].(string); ok {
+			result = map[string]interface{}{str: attrs[1]}
+		}
+	} else if len(attrs) == 1 {
+		if attr, ok := attrs[0].(map[string]interface{}); ok {
+			result = attr
+		}
+
+		if attr, ok := attrs[0].(interface{}); ok {
+			result = attr
+		}
+	}
+	return
+}
+
+func convertInterfaceToMap(values interface{}) map[string]interface{} {
+	attrs := map[string]interface{}{}
+
+	switch value := values.(type) {
+	case map[string]interface{}:
+		for k, v := range value {
+			attrs[ToSnake(k)] = v
+		}
+	case []interface{}:
+		for _, v := range value {
+			for key, value := range convertInterfaceToMap(v) {
+				attrs[key] = value
+			}
+		}
+	case interface{}:
+		reflectValue := reflect.ValueOf(values)
+
+		switch reflectValue.Kind() {
+		case reflect.Map:
+			for _, key := range reflectValue.MapKeys() {
+				attrs[ToSnake(key.Interface().(string))] = reflectValue.MapIndex(key).Interface()
+			}
+		default:
+			scope := Scope{Value: values}
+			for _, field := range scope.Fields() {
+				if !field.IsBlank {
+					attrs[field.DBName] = field.Value
+				}
+			}
+		}
+	}
+	return attrs
+}