Add questionToken option to transform

docs/src/content/docs/node.md

@@ -118,7 +118,7 @@ That would result in the following change:
 
 ```diff
 - updated_at?: string;
-+ updated_at?: Date;
++ updated_at: Date | null;
 ```
 
 #### Example: `Blob` types
@@ -158,7 +158,51 @@ Resultant diff with correctly-typed `file` property:
 
 ```diff
 - file?: string;
-+ file?: Blob;
++ file: Blob | null;
+```
+
+#### Example: Add "?" token to property
+
+It is not possible to create a property with the optional "?" token with the above `transform` functions. The transform function also accepts a different return object, which allows you to add a "?" token to the property. Here's an example schema:
+
+```yaml
+Body_file_upload:
+  type: object;
+  properties:
+    file:
+      type: string;
+      format: binary;
+      required: true;
+```
+
+Here we return an object with a schema property, which is the same as the above example, but we also add a `questionToken` property, which will add the "?" token to the property.
+
+```ts
+import openapiTS from "openapi-typescript";
+import ts from "typescript";
+
+const BLOB = ts.factory.createIdentifier("Blob"); // `Blob`
+const NULL = ts.factory.createLiteralTypeNode(ts.factory.createNull()); // `null`
+
+const ast = await openapiTS(mySchema, {
+  transform(schemaObject, metadata) {
+    if (schemaObject.format === "binary") {
+      return {
+        schema: schemaObject.nullable
+          ? ts.factory.createUnionTypeNode([BLOB, NULL])
+          : BLOB,
+        questionToken: true,
+      };
+    }
+  },
+});
+```
+
+Resultant diff with correctly-typed `file` property and "?" token:
+
+```diff
+- file: Blob;
++ file?: Blob | null;
 ```
 
 Any [Schema Object](https://spec.openapis.org/oas/latest.html#schema-object) present in your schema will be run through this formatter (even remote ones!). Also be sure to check the `metadata` parameter for additional context that may be helpful.

packages/openapi-typescript/src/transform/components-object.ts

@@ -1,6 +1,7 @@
 import ts from "typescript";
 import {
   NEVER,
+  QUESTION_TOKEN,
   addJSDocComment,
   tsModifiers,
   tsPropertyIndex,
@@ -9,6 +10,7 @@ import { createRef, debug, getEntries } from "../lib/utils.js";
 import {
   ComponentsObject,
   GlobalContext,
+  SchemaObject,
   TransformNodeOptions,
 } from "../types.js";
 import transformHeaderObject from "./header-object.js";
@@ -51,14 +53,31 @@ export default function transformComponentsObject(
     const items: ts.TypeElement[] = [];
     if (componentsObject[key]) {
       for (const [name, item] of getEntries(componentsObject[key], ctx)) {
-        const subType = transformers[key](item, {
+        let subType = transformers[key](item, {
           path: createRef(["components", key, name]),
           ctx,
         });
+
+        let hasQuestionToken = false;
+        if (ctx.transform) {
+          const result = ctx.transform(item as SchemaObject, {
+            path: createRef(["components", key, name]),
+            ctx,
+          });
+          if (result) {
+            if ("schema" in result) {
+              subType = result.schema;
+              hasQuestionToken = result.questionToken;
+            } else {
+              subType = result;
+            }
+          }
+        }
+
         const property = ts.factory.createPropertySignature(
           /* modifiers     */ tsModifiers({ readonly: ctx.immutable }),
           /* name          */ tsPropertyIndex(name),
-          /* questionToken */ undefined,
+          /* questionToken */ hasQuestionToken ? QUESTION_TOKEN : undefined,
           /* type          */ subType,
         );
         addJSDocComment(item as unknown as any, property); // eslint-disable-line @typescript-eslint/no-explicit-any

packages/openapi-typescript/src/transform/schema-object.ts

@@ -87,16 +87,6 @@ export function transformSchemaObjectWithComposition(
     return oapiRef(schemaObject.$ref);
   }
 
-  /**
-   * transform()
-   */
-  if (typeof options.ctx.transform === "function") {
-    const result = options.ctx.transform(schemaObject, options);
-    if (result !== undefined && result !== null) {
-      return result;
-    }
-  }
-
   /**
    * const (valid for any type)
    */
@@ -461,18 +451,31 @@ function transformSchemaObjectCore(
             continue;
           }
         }
-        const optional =
+        let optional =
           schemaObject.required?.includes(k) ||
           ("default" in v && options.ctx.defaultNonNullable)
             ? undefined
             : QUESTION_TOKEN;
-        const type =
+        let type =
           "$ref" in v
             ? oapiRef(v.$ref)
             : transformSchemaObject(v, {
                 ...options,
                 path: createRef([options.path ?? "", k]),
               });
+
+        if (typeof options.ctx.transform === "function") {
+          const result = options.ctx.transform(v, options);
+          if (result) {
+            if ("schema" in result) {
+              type = result.schema;
+              optional = result.questionToken ? QUESTION_TOKEN : optional;
+            } else {
+              type = result;
+            }
+          }
+        }
+
         const property = ts.factory.createPropertySignature(
           /* modifiers     */ tsModifiers({
             readonly:

packages/openapi-typescript/src/types.ts

@@ -467,6 +467,11 @@ export type SchemaObject = {
   | {}
 );
 
+export interface TransformObject {
+  schema: ts.TypeNode;
+  questionToken: boolean;
+}
+
 export interface StringSubtype {
   type: "string" | ["string", "null"];
   enum?: (string | ReferenceObject)[];
@@ -646,7 +651,7 @@ export interface OpenAPITSOptions {
   transform?: (
     schemaObject: SchemaObject,
     options: TransformNodeOptions,
-  ) => ts.TypeNode | undefined;
+  ) => ts.TypeNode | TransformObject | undefined;
   /** Modify TypeScript types built from Schema Objects */
   postTransform?: (
     type: ts.TypeNode,

packages/openapi-typescript/test/node-api.test.ts

@@ -6,6 +6,10 @@ import { TestCase } from "./test-helpers.js";
 
 const EXAMPLES_DIR = new URL("../examples/", import.meta.url);
 
+const DATE = ts.factory.createTypeReferenceNode(
+  ts.factory.createIdentifier("Date"),
+);
+
 describe("Node.js API", () => {
   const tests: TestCase<any, OpenAPITSOptions>[] = [
     [
@@ -382,9 +386,49 @@ export type operations = Record<string, never>;`,
                * then use the `typescript` parser and it will tell you the desired
                * AST
                */
-              return ts.factory.createTypeReferenceNode(
-                ts.factory.createIdentifier("Date"),
-              );
+              return DATE;
+            }
+          },
+        },
+      },
+    ],
+    [
+      "options > transform with schema object",
+      {
+        given: {
+          openapi: "3.1",
+          info: { title: "Test", version: "1.0" },
+          components: {
+            schemas: {
+              Date: { type: "string", format: "date-time" },
+            },
+          },
+        },
+        want: `export type paths = Record<string, never>;
+export type webhooks = Record<string, never>;
+export interface components {
+    schemas: {
+        /** Format: date-time */
+        Date?: Date;
+    };
+    responses: never;
+    parameters: never;
+    requestBodies: never;
+    headers: never;
+    pathItems: never;
+}
+export type $defs = Record<string, never>;
+export type operations = Record<string, never>;`,
+        options: {
+          transform(schemaObject) {
+            if (
+              "format" in schemaObject &&
+              schemaObject.format === "date-time"
+            ) {
+              return {
+                schema: DATE,
+                questionToken: true,
+              };
             }
           },
         },

packages/openapi-typescript/test/transform/components-object.test.ts

@@ -1,11 +1,14 @@
 import { fileURLToPath } from "node:url";
-import { astToString } from "../../src/lib/ts.js";
+import ts from "typescript";
+import { NULL, astToString } from "../../src/lib/ts.js";
 import transformComponentsObject from "../../src/transform/components-object.js";
 import type { GlobalContext } from "../../src/types.js";
 import { DEFAULT_CTX, TestCase } from "../test-helpers.js";
 
 const DEFAULT_OPTIONS = DEFAULT_CTX;
 
+const DATE = ts.factory.createTypeReferenceNode("Date");
+
 describe("transformComponentsObject", () => {
   const tests: TestCase<any, GlobalContext>[] = [
     [
@@ -461,6 +464,45 @@ describe("transformComponentsObject", () => {
         options: { ...DEFAULT_OPTIONS, excludeDeprecated: true },
       },
     ],
+    [
+      "transform > with transform object",
+      {
+        given: {
+          schemas: {
+            Alpha: {
+              type: "object",
+              properties: {
+                z: { type: "string", format: "date-time" },
+              },
+            },
+          },
+        },
+        want: `{
+    schemas: {
+        Alpha: {
+            /** Format: date-time */
+            z?: Date | null;
+        };
+    };
+    responses: never;
+    parameters: never;
+    requestBodies: never;
+    headers: never;
+    pathItems: never;
+}`,
+        options: {
+          ...DEFAULT_OPTIONS,
+          transform(schemaObject) {
+            if (schemaObject.format === "date-time") {
+              return {
+                schema: ts.factory.createUnionTypeNode([DATE, NULL]),
+                questionToken: true,
+              };
+            }
+          },
+        },
+      },
+    ],
   ];
 
   for (const [

packages/openapi-typescript/test/transform/request-body-object.test.ts

@@ -1,4 +1,5 @@
 import { fileURLToPath } from "node:url";
+import ts from "typescript";
 import { astToString } from "../../src/lib/ts.js";
 import transformRequestBodyObject from "../../src/transform/request-body-object.js";
 import { DEFAULT_CTX, TestCase } from "../test-helpers.js";
@@ -8,6 +9,8 @@ const DEFAULT_OPTIONS = {
   ctx: { ...DEFAULT_CTX },
 };
 
+const BLOB = ts.factory.createTypeReferenceNode("Blob");
+
 describe("transformRequestBodyObject", () => {
   const tests: TestCase[] = [
     [
@@ -50,6 +53,45 @@ describe("transformRequestBodyObject", () => {
         // options: DEFAULT_OPTIONS,
       },
     ],
+    [
+      "optional blob property with transform",
+      {
+        given: {
+          content: {
+            "application/json": {
+              schema: {
+                type: "object",
+                properties: {
+                  blob: { type: "string", format: "binary" },
+                },
+              },
+            },
+          },
+        },
+        want: `{
+    content: {
+        "application/json": {
+            /** Format: binary */
+            blob?: Blob;
+        };
+    };
+}`,
+        options: {
+          ...DEFAULT_OPTIONS,
+          ctx: {
+            ...DEFAULT_CTX,
+            transform(schemaObject) {
+              if (schemaObject.format === "binary") {
+                return {
+                  schema: BLOB,
+                  questionToken: true,
+                };
+              }
+            },
+          },
+        },
+      },
+    ],
   ];
 
   for (const [