When Swagger documentation isn't showing correctly with Koa annotations, the issue often lies with how Swagger is set up, or how the annotations are being parsed. Here are some common reasons and solutions:
---
1. Incorrect Setup of Swagger for Koa
Ensure that you have correctly configured Swagger to work with Koa. A common library for this is koa-swagger-decorator or koa-openapi. Check the following:
Swagger initialization is done before route definitions.
Your Swagger UI middleware is added to the Koa app.
Example with koa-swagger-decorator:
Ensure the mapDir function points to the directory where your annotated routes are defined.
---
2. Missing or Incorrect Swagger Annotations
Swagger annotations should be properly defined in your routes. If they are missing or incorrectly formatted, the documentation may not display.
Example of a properly annotated route:
Check the following:
The annotations match the expected format.
The imported decorators (request, summary, tags, etc.) are from the correct library.
---
3. Issue with Route Discovery
If you're using mapDir, the library may not correctly parse your routes if:
The files don't export the routes properly.
There are syntax errors or non-standard practices in your code.
Solution:
Confirm that your routes are being correctly exported and follow the expected patterns for the Swagger library you're using.
Ensure your files are named appropriately if the library relies on naming conventions (e.g., *.js).
---
4. Swagger UI Not Loading
If the Swagger UI page is blank or errors out:
Verify that Swagger UI middleware is correctly serving the documentation.
Check your browser's developer console for errors (e.g., CORS issues, 404 errors).
Example of serving Swagger UI:
5. Incorrect Middleware Order
Ensure middleware is added in the correct order. For example:
Debugging Steps
1. Check Swagger JSON Output: Access the raw Swagger JSON to verify that it's being generated correctly (http://localhost:3000/swagger-json).
2. Log Routes: Use console.log(router.stack) to ensure your routes are being registered.
3. Update Dependencies: Outdated libraries can cause issues. Update koa-swagger-decorator, koa-router, and other dependencies.
---
1. Incorrect Setup of Swagger for Koa
Ensure that you have correctly configured Swagger to work with Koa. A common library for this is koa-swagger-decorator or koa-openapi. Check the following:
Swagger initialization is done before route definitions.
Your Swagger UI middleware is added to the Koa app.
Example with koa-swagger-decorator:
JavaScript:
const Koa = require('koa');
const Router = require('koa-router');
const { SwaggerRouter } = require('koa-swagger-decorator');
const app = new Koa();
const router = new SwaggerRouter();
// Swagger config
router.swagger({
title: 'API Docs',
description: 'API documentation',
version: '1.0.0',
});
// Add your routes
router.mapDir(__dirname + '/routes');
// Middleware
app.use(router.routes());
app.use(router.allowedMethods());
app.listen(3000, () => {
console.log('Server running on http://localhost:3000');
});Ensure the mapDir function points to the directory where your annotated routes are defined.
---
2. Missing or Incorrect Swagger Annotations
Swagger annotations should be properly defined in your routes. If they are missing or incorrectly formatted, the documentation may not display.
Example of a properly annotated route:
JavaScript:
const { request, summary, tags } = require('koa-swagger-decorator');
const tag = tags(['User']);
module.exports = class UserController {
@request('GET', '/users')
@summary('Get all users')
@tag
static async getUsers(ctx) {
ctx.body = [{ id: 1, name: 'John Doe' }];
}
};Check the following:
The annotations match the expected format.
The imported decorators (request, summary, tags, etc.) are from the correct library.
---
3. Issue with Route Discovery
If you're using mapDir, the library may not correctly parse your routes if:
The files don't export the routes properly.
There are syntax errors or non-standard practices in your code.
Solution:
Confirm that your routes are being correctly exported and follow the expected patterns for the Swagger library you're using.
Ensure your files are named appropriately if the library relies on naming conventions (e.g., *.js).
---
4. Swagger UI Not Loading
If the Swagger UI page is blank or errors out:
Verify that Swagger UI middleware is correctly serving the documentation.
Check your browser's developer console for errors (e.g., CORS issues, 404 errors).
Example of serving Swagger UI:
JavaScript:
router.swagger({
title: 'API Docs',
description: 'API documentation',
version: '1.0.0',
swaggerOptions: {
swaggerVersion: '2.0',
},
});
---5. Incorrect Middleware Order
Ensure middleware is added in the correct order. For example:
JavaScript:
app.use(cors());
app.use(bodyParser());
app.use(router.routes());
app.use(router.allowedMethods());
---Debugging Steps
1. Check Swagger JSON Output: Access the raw Swagger JSON to verify that it's being generated correctly (http://localhost:3000/swagger-json).
2. Log Routes: Use console.log(router.stack) to ensure your routes are being registered.
3. Update Dependencies: Outdated libraries can cause issues. Update koa-swagger-decorator, koa-router, and other dependencies.