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Version: Next
note

Last checked with Wasp 0.23, swagger-jsdoc 6, and swagger-ui-express 5.

This guide depends on external libraries or services, so it may become outdated over time. We do our best to keep it up to date, but make sure to check their documentation for any changes.

Swagger UI

This guide shows you how to add Swagger UI documentation to your Wasp APIs, making it easy to explore and test your endpoints.

Setting up Swagger UI​

1. Install dependencies​

Install the required packages:

npm install swagger-jsdoc swagger-ui-express
npm install --save-dev @types/swagger-jsdoc @types/swagger-ui-express

2. Configure the API namespace in main.wasp​

Add an API namespace for the Swagger UI endpoint:

main.wasp
app MyApp {
  wasp: {
    version: "^0.21.0"
  },
  title: "my-app",
}

apiNamespace swaggerUI {
  middlewareConfigFn: import { swaggerMiddleware } from "@src/swagger-ui",
  path: "/api-docs"
}

api getStatus {
  fn: import { getStatus } from "@src/apis",
  auth: false,
  entities: [],
  httpRoute: (GET, "/status")
}

3. Create the spec generator script​

Because swagger-jsdoc scans source files at runtime and src/ is not available in the production Docker image, you need to pre-generate the spec as a TypeScript module that gets bundled with the server.

Create scripts/generate-swagger.js:

scripts/generate-swagger.js
import swaggerJsdoc from "swagger-jsdoc";
import { writeFileSync } from "fs";

const spec = swaggerJsdoc({
  definition: {
    openapi: "3.0.0",
    info: {
      title: "My API",
      version: "1.0.0",
      description: "API documentation for my Wasp application",
      contact: {
        name: "API Support",
        url: "https://example.com",
        email: "support@example.com",
      },
    },
    components: {
      securitySchemes: {
        bearerAuth: {
          type: "http",
          scheme: "bearer",
          bearerFormat: "JWT",
          description: "Enter your JWT token in the format: Bearer {token}",
        },
      },
    },
    security: [{ bearerAuth: [] }],
  },
  apis: ["./src/**/*.ts", "!./src/swaggerSpec.ts"],
});

writeFileSync(
  "./src/swaggerSpec.ts",
  `const swaggerSpec = ${JSON.stringify(spec, null, 2)} as const;\nexport default swaggerSpec;\n`,
);
console.log("swaggerSpec.ts generated");

Run this script whenever you add or change JSDoc annotations:

node scripts/generate-swagger.js

This generates src/swaggerSpec.ts, which gets bundled into the server and works in both dev and production.

note

You may want to add src/swaggerSpec.ts to your .gitignore since it's a generated file.

4. Create the Swagger middleware​

Create the Swagger UI middleware that serves the pre-generated spec:

src/swagger-ui.js
import * as express from "express";
import helmet from "helmet";
import swaggerUi from "swagger-ui-express";
import { env, MiddlewareConfigFn } from "wasp/server";
import baseSwaggerDoc from "./swaggerSpec";

const swaggerDoc = {
  ...baseSwaggerDoc,
  servers: [{ url: env.WASP_SERVER_URL, description: "API server" }],
};

export const swaggerMiddleware = (middlewareConfig) => {
  middlewareConfig.delete("helmet");
  middlewareConfig.set(
    "helmet",
    helmet({
      contentSecurityPolicy: false,
      hsts: false,
    }),
  );

  swaggerUi.serve.forEach((handler, i) => {
    middlewareConfig.set(`swaggerServe${i}`, handler);
  });

  middlewareConfig.set("swaggerSetup", (req, res, next) => {
    return swaggerUi.setup(swaggerDoc, {
      explorer: true,
      customCss: ".swagger-ui .topbar { display: none }",
      swaggerOptions: {
        persistAuthorization: true,
        url: "/api-docs/swagger.json",
      },
    })(req, res, next);
  });

  return middlewareConfig;
};

5. Document your APIs​

Add JSDoc comments with Swagger annotations above your API definitions:

src/apis.js
import { GetStatus } from "wasp/server/api";

/**
 * @swagger
 * /status:
 *   get:
 *     summary: Get API status
 *     description: Returns the current status of the API
 *     tags:
 *       - Status
 *     security:
 *       - bearerAuth: []
 *     responses:
 *       200:
 *         description: Successful response
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 message:
 *                   type: string
 *       401:
 *         description: Unauthorized
 *       500:
 *         description: Server error
 */
export const getStatus = async (req, res) => {
  return res.json({ message: "OK" });
};

6. Access the documentation​

Start your Wasp application and navigate to http://localhost:3001/api-docs to see your API documentation.

Documenting Different Request Types​

POST Request with Body​

/**
 * @swagger
 * /users:
 *   post:
 *     summary: Create a new user
 *     tags:
 *       - Users
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             type: object
 *             required:
 *               - email
 *               - password
 *             properties:
 *               email:
 *                 type: string
 *                 format: email
 *               password:
 *                 type: string
 *                 minLength: 8
 *     responses:
 *       201:
 *         description: User created successfully
 *       400:
 *         description: Invalid input
 */

Path Parameters​

/**
 * @swagger
 * /users/{id}:
 *   get:
 *     summary: Get user by ID
 *     tags:
 *       - Users
 *     parameters:
 *       - in: path
 *         name: id
 *         required: true
 *         schema:
 *           type: string
 *         description: User ID
 *     responses:
 *       200:
 *         description: User found
 *       404:
 *         description: User not found
 */

Query Parameters​

/**
 * @swagger
 * /users:
 *   get:
 *     summary: List users
 *     tags:
 *       - Users
 *     parameters:
 *       - in: query
 *         name: page
 *         schema:
 *           type: integer
 *           default: 1
 *         description: Page number
 *       - in: query
 *         name: limit
 *         schema:
 *           type: integer
 *           default: 10
 *         description: Items per page
 *     responses:
 *       200:
 *         description: List of users
 */

Customization​

Custom Styling​

You can customize the Swagger UI appearance:

swaggerUi.setup(swaggerDoc, {
  customCss: `
    .swagger-ui .topbar { display: none }
    .swagger-ui .info { margin: 20px 0 }
  `,
  customSiteTitle: "My API Documentation",
  customfavIcon: "/favicon.ico",
});

Group APIs with Tags​

Use tags to organize your endpoints. Add a tags array to the definition in scripts/generate-swagger.js:

const spec = swaggerJsdoc({
  definition: {
    // ... other config
    tags: [
      { name: "Users", description: "User management endpoints" },
      { name: "Posts", description: "Blog post endpoints" },
      { name: "Auth", description: "Authentication endpoints" },
    ],
  },
  apis: ["./src/**/*.ts", "!./src/swaggerSpec.ts"],
});

For more options, see the swagger-jsdoc documentation and swagger-ui-express documentation.