hey-api · mrlubos · Sep 23, 2025 · Sep 22, 2025 · Sep 23, 2025 · Sep 23, 2025
diff --git a/.changeset/chilled-pumas-exist.md b/.changeset/chilled-pumas-exist.md
@@ -0,0 +1,5 @@
+---
+'@hey-api/openapi-ts': patch
+---
+
+fix(parser): add `propertiesRequiredByDefault` transform option
diff --git a/docs/openapi-ts/configuration/parser.md b/docs/openapi-ts/configuration/parser.md
@@ -376,6 +376,40 @@ export default {
 
 You can customize the naming and casing pattern for `enums` schemas using the `.name` and `.case` options.
 
+### Properties required by default
+
+By default, any object schema with a missing `required` keyword is interpreted as "no properties are required." This is the correct behavior according to the OpenAPI standard. However, some specifications interpret a missing `required` keyword as "all properties should be required."
+
+This option allows you to change the default behavior so that properties are required by default unless explicitly marked as optional.
+
+::: code-group
+
+```js [default]
+export default {
+  input: 'hey-api/backend', // sign up at app.heyapi.dev
+  output: 'src/client',
+  parser: {
+    transforms: {
+      propertiesRequiredByDefault: false, // [!code ++]
+    },
+  },
+};
+```
+
+```js [required]
+export default {
+  input: 'hey-api/backend', // sign up at app.heyapi.dev
+  output: 'src/client',
+  parser: {
+    transforms: {
+      propertiesRequiredByDefault: true, // [!code ++]
+    },
+  },
+};
+```
+
+:::
+
 ### Read-write
 
 Your schemas might contain read-only or write-only fields. Using such schemas directly could mean asking the user to provide a read-only field in requests, or expecting a write-only field in responses. We separate schemas for requests and responses if direct usage would result in such scenarios.

diff --git a/packages/openapi-ts-tests/main/test/3.0.x.test.ts b/packages/openapi-ts-tests/main/test/3.0.x.test.ts
@@ -635,6 +635,19 @@ describe(`OpenAPI ${version}`, () => {
       }),
       description: 'transforms an array',
     },
+    {
+      config: createConfig({
+        input: 'dutchie.json',
+        output: 'transforms-properties-required-by-default',
+        parser: {
+          transforms: {
+            propertiesRequiredByDefault: true,
+          },
+        },
+        plugins: ['@hey-api/typescript'],
+      }),
+      description: 'makes all object properties required by default',
+    },
     {
       config: createConfig({
         input: 'type-invalid.json',

diff --git a/...ts-tests/main/test/__snapshots__/3.0.x/transforms-properties-required-by-default/index.ts b/...ts-tests/main/test/__snapshots__/3.0.x/transforms-properties-required-by-default/index.ts
@@ -0,0 +1,3 @@
+// This file is auto-generated by @hey-api/openapi-ts
+
+export type * from './types.gen';
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		// This file is auto-generated by @hey-api/openapi-ts

		export type * from './types.gen';