Add Distinct option for SelectBuilder (#34)

filterapply.go

@@ -59,6 +59,8 @@ func apply(statement squirrel.SelectBuilder, f yaormfilter.Filter, dbp DBProvide
 			if dbp.CanSelectForUpdate() {
 				statement = statement.Suffix(fmt.Sprintf(`FOR UPDATE OF %s`, dbp.EscapeValue(applier.tableName)))
 			}
+		case yaormfilter.RequestOptions.SelectDistinct:
+			statement = statement.Distinct()
 		}
 	}
 	for _, orderBy := range f.GetOrderBy() {

filterapply_test.go

@@ -166,3 +166,31 @@ func TestFilterApplier_LoadColumns(t *testing.T) {
 		assert.False(t, models[1].(*testdata.Category).UpdatedAt.IsZero())
 	}
 }
+
+func TestFilterApplier_Distinct(t *testing.T) {
+	killDb, err := testdata.SetupTestDatabase("test")
+	defer killDb()
+
+	assert.NoError(t, err)
+	dbp, err := yaorm.NewDBProvider(context.TODO(), "test")
+	assert.NoError(t, err)
+	post := &testdata.Post{}
+	saveModel(t, dbp, post)
+	postChild := &testdata.Post{ParentPostID: post.ID}
+	saveModel(t, dbp, postChild)
+	postChild2 := &testdata.Post{ParentPostID: post.ID}
+	saveModel(t, dbp, postChild2)
+
+	f := testdata.NewPostFilter()
+	f.ChildrenPosts(testdata.NewPostFilter().
+		ParentPostID(yaormfilter.NewInt64Filter().Equals(post.ID)))
+	models, err := yaorm.GenericSelectAll(dbp, f)
+	assert.NoError(t, err)
+	// We do not set the filter Distinct, so we should have one row per matching children
+	assert.Equal(t, 2, len(models))
+
+	f.Distinct()
+	models, err = yaorm.GenericSelectAll(dbp, f)
+	assert.NoError(t, err)
+	assert.Equal(t, 1, len(models))
+}

testdata/post.go

@@ -40,6 +40,15 @@ func NewPostFilter() *PostFilter {
 	return &PostFilter{}
 }
 
+func (f *PostFilter) AddOption(opt yaormfilter.RequestOption) yaormfilter.Filter {
+	f.AddOption_(opt)
+	return f
+}
+
+func (f *PostFilter) Distinct() {
+	f.AddOption("SelectDistinct")
+}
+
 func (f *PostFilter) ID(v yaormfilter.ValueFilter) *PostFilter {
 	f.FilterID = v
 	return f

yaormfilter/filter.go

@@ -38,9 +38,11 @@ type RequestOption string
 // RequestOptions represents the Enum of Request options
 var RequestOptions = struct {
 	SelectForUpdate RequestOption
+	SelectDistinct  RequestOption
 	LeftJoin        RequestOption
 }{
 	SelectForUpdate: "SelectForUpdate",
+	SelectDistinct:  "SelectDistinct",
 	LeftJoin:        "LeftJoin",
 }
 
@@ -103,7 +105,7 @@ func (mf *ModelFilter) GetSelectOptions() []RequestOption {
 	opts := []RequestOption{}
 	for _, opt := range mf.options {
 		switch opt {
-		case RequestOptions.SelectForUpdate:
+		case RequestOptions.SelectForUpdate, RequestOptions.SelectDistinct:
 			opts = append(opts, opt)
 		}
 	}