Add schema to postTransform options

Closes openapi-ts#2013

Author: duncanbeevers

docs/6.x/node.md

@@ -122,6 +122,16 @@ Resultant diff with correctly-typed `file` property:
 +    file?: Blob;
 ```
 
-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.
+#### transform / postTransform metadata
 
-There are many other uses for this besides checking `format`. Because this must return a **string** you can produce any arbitrary TypeScript code you’d like (even your own custom types).
+Any [Schema Object](https://spec.openapis.org/oas/latest.html#schema-object) present in your schema will be run through `transform`, prior to its conversion to a TypeScript AST node, and `postTransform` after its conversion, including remote schemas!
+
+The `metadata` parameter present on both `transform` and `postTransform` has additional context that may be helpful.
+
+| Property | Description |
+|-|-|
+| `metadata.path` | A [`$ref`](https://json-schema.org/understanding-json-schema/structuring#dollarref) URI string, pointing to the current schema object |
+| `metadata.schema` | The schema object being transformed (only present for `postTransform`) |
+| `metadata.ctx` | The GlobalContext object, containing
+
+There are many other uses for this besides checking `format`. Because `tranform` may return a **string** you can produce any arbitrary TypeScript code you’d like (even your own custom types).

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

@@ -35,16 +35,18 @@ export default function transformComponentsObject(componentsObject: ComponentsOb
 
     const items: ts.TypeElement[] = [];
     if (componentsObject[key]) {
-      for (const [name, item] of getEntries(componentsObject[key], ctx)) {
+      for (const [name, item] of getEntries<SchemaObject>(componentsObject[key], ctx)) {
         let subType = transformers[key](item, {
           path: createRef(["components", key, name]),
+          schema: item,
           ctx,
         });
 
         let hasQuestionToken = false;
         if (ctx.transform) {
-          const result = ctx.transform(item as SchemaObject, {
+          const result = ctx.transform(item, {
             path: createRef(["components", key, name]),
+            schema: item,
             ctx,
           });
           if (result) {

packages/openapi-typescript/src/transform/index.ts

@@ -14,7 +14,7 @@ const transformers: Record<SchemaTransforms, (node: any, options: GlobalContext)
   paths: transformPathsObject,
   webhooks: transformWebhooksObject,
   components: transformComponentsObject,
-  $defs: (node, options) => transformSchemaObject(node, { path: createRef(["$defs"]), ctx: options }),
+  $defs: (node, options) => transformSchemaObject(node, { path: createRef(["$defs"]), ctx: options, schema: node }),
 };
 
 export default function transformSchema(schema: OpenAPI3, ctx: GlobalContext) {

packages/openapi-typescript/src/types.ts

@@ -704,5 +704,6 @@ export type $defs = Record<string, SchemaObject>;
 /** generic options for most internal transform* functions */
 export interface TransformNodeOptions {
   path?: string;
+  schema?: SchemaObject | ReferenceObject;
   ctx: GlobalContext;
 }

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

@@ -1,7 +1,7 @@
 import { fileURLToPath } from "node:url";
 import ts from "typescript";
 import openapiTS, { COMMENT_HEADER, astToString } from "../src/index.js";
-import type { OpenAPITSOptions } from "../src/types.js";
+import type { OpenAPITSOptions, ReferenceObject, SchemaObject } from "../src/types.js";
 import type { TestCase } from "./test-helpers.js";
 
 const EXAMPLES_DIR = new URL("../examples/", import.meta.url);
@@ -537,6 +537,11 @@ export type operations = Record<string, never>;`,
           components: {
             schemas: {
               Date: { type: "string", format: "date-time" },
+              Set: {
+                ["x-string-enum-to-set"]: true,
+                type: "string",
+                enum: ["low", "medium", "high"],
+              },
             },
           },
         },
@@ -546,6 +551,8 @@ export interface components {
     schemas: {
         /** Format: date-time */
         Date: DateOrTime;
+        /** @enum {string} */
+        Set: Set<"low" | "medium" | "high">;
     };
     responses: never;
     parameters: never;
@@ -563,7 +570,40 @@ 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("DateOrTime"));
+              return ts.factory.createTypeReferenceNode(
+                ts.factory.createIdentifier("DateOrTime")
+              );
+            }
+
+            // Previously, in order to access the schema in postTransform,
+            // you could resolve the schema using the path.
+            // Now, the schema is made available directly on the options.
+            // const schema = options.path
+            //   ? options.ctx.resolve<ReferenceObject | SchemaObject>(options.path)
+            //   : undefined;
+            const schema = options.schema;
+
+            if (
+              schema &&
+              !("$ref" in schema) &&
+              Object.hasOwn(schema, "x-string-enum-to-set") &&
+              schema.type === "string" &&
+              schema.enum?.every((enumMember) => {
+                return typeof enumMember === "string";
+              })
+            ) {
+              return ts.factory.createTypeReferenceNode(
+                ts.factory.createIdentifier("Set"),
+                [
+                  ts.factory.createUnionTypeNode(
+                    schema.enum.map((value) => {
+                      return ts.factory.createLiteralTypeNode(
+                        ts.factory.createStringLiteral(value)
+                      );
+                    })
+                  ),
+                ]
+              );
             }
           },
         },