fix: add omitempty support for list types with pointer_omitempty (#413)

fixed `pointer_omitempty` not being applied to list types when
`use_struct_references` is enabled. List fields like `[String!]` now
correctly get the `omitempty` JSON tag

---------

Co-authored-by: huo <huo@gmail.com>
Co-authored-by: gofulljs <gofulljs@gmail.com>

Author: 3 people

docs/CHANGELOG.md

@@ -32,6 +32,7 @@ Note that genqlient now requires Go 1.23 or higher, and is tested through Go 1.2
 
 ### Bug fixes:
 
+- fixed `pointer_omitempty` not being applied to list types when `use_struct_references` is enabled. List fields like `[String!]` now correctly get the `omitempty` JSON tag.
 - fixed minor typos and grammatical issues across the project
 
 ## v0.8.1

generate/convert.go

@@ -239,7 +239,20 @@ func (g *generator) convertType(
 		// Type is a list.
 		elem, err := g.convertType(
 			namePrefix, typ.Elem, selectionSet, options, queryOptions)
-		return &goSliceType{elem}, err
+		// For list types, we need to handle pointer_omitempty here because
+		// the code below won't be executed for slices.
+		// If the list itself is nullable (e.g., [String!] vs [String!]!),
+		// and pointer_omitempty is configured, we should set omitempty.
+		if err != nil {
+			return nil, err
+		}
+		if g.Config.Optional == "pointer_omitempty" && !typ.NonNull {
+			if options.Omitempty == nil {
+				oe := true
+				options.Omitempty = &oe
+			}
+		}
+		return &goSliceType{elem}, nil
 	}
 
 	// If this is a builtin type or custom scalar, just refer to it.

generate/generate_test.go

@@ -245,6 +245,7 @@ func TestGenerateWithConfig(t *testing.T) {
 			"PointersOmitEmpty.graphql",
 			"Omitempty.graphql",
 			"ListInput.graphql",
+			"ListInputOmitempty.graphql",
 		}, &Config{
 			Optional: "pointer_omitempty",
 			Bindings: map[string]*TypeBinding{

generate/testdata/queries/ListInputOmitempty.graphql

@@ -0,0 +1,5 @@
+query ListInputOmitemptyQuery($names: [String!]) {
+  user(query: {names: $names}) {
+    id
+  }
+}

generate/testdata/snapshots/TestGenerate-ListInputOmitempty.graphql-ListInputOmitempty.graphql.go

@@ -0,0 +1,9 @@
+{
+  "operations": [
+    {
+      "operationName": "ListInputOmitemptyQuery",
+      "query": "\nquery ListInputOmitemptyQuery ($names: [String!]) {\n\tuser(query: {names:$names}) {\n\t\tid\n\t}\n}\n",
+      "sourceLocation": "testdata/queries/ListInputOmitempty.graphql"
+    }
+  ]
+}