docs: add some comment

model.go

@@ -14,9 +14,27 @@ type Model struct {
 	DeletedAt DeletedAt `gorm:"index"`
 }
 
+// UnDelete clear model's deleted info, you need save this model manually
+func (m *Model) UnDelete() {
+	m.DeletedAt.Valid = false
+}
+
+// ModelSupportUnique model that support soft delete and unique index
+//
+// For example
+//
+// when you annouce an unique index for column A,
+// gorm will automate create a composite index for A & deleted_flag.
+//
+// create: deleted_flag default to 0
+// delete: set deleted_flag's value to primary id to avoid unique conflict
 type ModelSupportUnique struct {
-	ID          uint `gorm:"primarykey"`
-	CreatedAt   time.Time
-	UpdatedAt   time.Time
+	Model
 	DeletedFlag DeletedFlag `gorm:"type:BIGINT UNSIGNED NOT NULL DEFAULT 0" json:"deleted_flag"`
 }
+
+// UnDelete clear model's deleted info, you need save this model manually
+func (m *ModelSupportUnique) UnDelete() {
+	m.Model.UnDelete()
+	m.DeletedFlag = 0
+}

schema/index.go

@@ -65,7 +65,8 @@ func (schema *Schema) ParseIndexes() map[string]Index {
 
 						if !exists {
 							idx.Fields = append(idx.Fields, IndexOption{
-								Field: df,
+								Field:    df,
+								priority: 100,
 							})
 						}
 					}

soft_delete_unique.go

@@ -65,10 +65,11 @@ func (sd SoftDeleteUniqueDeleteClause) Build(clause.Builder) {
 func (sd SoftDeleteUniqueDeleteClause) MergeClause(*clause.Clause) {
 }
 
+var regReplaceUpdate = regexp.MustCompile(`UPDATE (.+?) WHERE `)
+
 func (sd SoftDeleteUniqueDeleteClause) ModifyStatement(stmt *Statement) {
-	re := regexp.MustCompile(`UPDATE (.*) WHERE `)
 	if sql := stmt.SQL.String(); sql != "" {
-		setClause := re.FindStringSubmatch(sql)[1]
+		setClause := regReplaceUpdate.FindStringSubmatch(sql)[1]
 		if setClause == "" {
 			return
 		}