fix(codegen): generate nullable.Nullable in arrays

jamietanna · jamietanna · commit 99eadbe66e96 · 2026-02-24T19:08:33.000Z
As a follow-up to #2185, we can make sure we generate a Nullable type if required to do so.
diff --git a/internal/test/issues/issue-2185/config.yaml b/internal/test/issues/issue-2185/config.yaml
@@ -0,0 +1,8 @@
+# yaml-language-server: $schema=../../../../configuration-schema.json
+package: issue2185
+output: issue2185.gen.go
+generate:
+  models: true
+output-options:
+  skip-prune: true
+  nullable-type: true
diff --git a/internal/test/issues/issue-2185/generate.go b/internal/test/issues/issue-2185/generate.go
@@ -0,0 +1,3 @@
+package issue2185
+
+//go:generate go run github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen --config=config.yaml spec.yaml
diff --git a/internal/test/issues/issue-2185/issue2185.gen.go b/internal/test/issues/issue-2185/issue2185.gen.go
diff --git a/internal/test/issues/issue-2185/issue2185_test.go b/internal/test/issues/issue-2185/issue2185_test.go
@@ -0,0 +1,19 @@
+package issue2185
+
+import (
+	"testing"
+
+	"github.com/oapi-codegen/nullable"
+	"github.com/stretchr/testify/require"
+)
+
+func TestContainer_UsesNullableType(t *testing.T) {
+	c := Container{
+		MayBeNull: []nullable.Nullable[string]{
+			nullable.NewNullNullable[string](),
+		},
+	}
+
+	require.Len(t, c.MayBeNull, 1)
+	require.True(t, c.MayBeNull[0].IsNull())
+}
diff --git a/internal/test/issues/issue-2185/spec.yaml b/internal/test/issues/issue-2185/spec.yaml
@@ -0,0 +1,15 @@
+openapi: "3.0.3"
+info:
+  title: test
+  version: 1.0.0
+components:
+  schemas:
+    Container:
+      required:
+        - "may-be-null"
+      properties:
+        "may-be-null":
+          type: array
+          items:
+            type: string
+            nullable: true
diff --git a/pkg/codegen/schema.go b/pkg/codegen/schema.go
@@ -603,8 +603,6 @@ func oapiSchemaToGoType(schema *openapi3.Schema, path []string, outSchema *Schem
 			return fmt.Errorf("error generating type for array: %w", err)
 		}
 
-		var itemPrefix string
-
 		if (arrayType.HasAdditionalProperties || len(arrayType.UnionElements) != 0) && arrayType.RefType == "" {
 			// If we have items which have additional properties or union values,
 			// but are not a pre-defined type, we need to define a type
@@ -622,12 +620,17 @@ func oapiSchemaToGoType(schema *openapi3.Schema, path []string, outSchema *Schem
 			arrayType.RefType = typeName
 		}
 
+		typeDeclaration := arrayType.TypeDecl()
 		if arrayType.OAPISchema != nil && arrayType.OAPISchema.Nullable {
-			itemPrefix = "*"
+			if globalState.options.OutputOptions.NullableType {
+				typeDeclaration = "nullable.Nullable[" + typeDeclaration + "]"
+			} else {
+				typeDeclaration = "*" + typeDeclaration
+			}
 		}
 
 		outSchema.ArrayType = &arrayType
-		outSchema.GoType = "[]" + itemPrefix + arrayType.TypeDecl()
+		outSchema.GoType = "[]" + typeDeclaration
 		outSchema.AdditionalTypes = arrayType.AdditionalTypes
 		outSchema.Properties = arrayType.Properties
 		outSchema.DefineViaAlias = true

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+package issue2185`
	`2`	`+`
	`3`	`+//go:generate go run github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen --config=config.yaml spec.yaml`