SyntaxError: Invalid regular expression during path-to-regexp conversion

[Xander Endre]

Hi there,

I've encountered an issue when using express-openapi with my Express.js application. This application was based on a fresh installation.

The error I'm facing is as follows:

C:\Users\Alex\Visual Studio Code\TestProject\CustomerService\api\node_modules\express\node_modules\path-to-regexp\index.js:128
  return new RegExp(path, flags);
         ^

SyntaxError: Invalid regular expression: /^\/customer\(?:([^\/]+?))\/?$/: Unmatched ')'

This error occurs when my application is starting up.

Here is my project structure:

C:.
│   app.js
│   package-lock.json
│   package.json
│
├───api
│   │   api-doc.js
│   │
│   └───paths
│       │   test.js
│       │
│       └───customer
│               customer.js
│               {id}.js
│
└───bin
        www

Here is my package.json

{
  "name": "customer-service",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    "node": "nodemon app.js",
    "start": "node ./bin/www"
  },
  "dependencies": {
    "cookie-parser": "~1.4.4",
    "debug": "~4.3.4",
    "dotenv": "^16.0.3",
    "express": "~4.18.2",
    "express-openapi": "^12.1.1",
    "morgan": "~1.10.0",
    "nodemon": "^2.0.20",
    "swagger-ui-express": "^4.6.1"
  }
}

Here is my code for the test.js, customer.js, and customer/{id}.js

module.exports = function () {
    let operations = {
        GET,
    };

    async function GET(req, res, next) {
        console.log("IN GET")
        console.log("REQUEST:", req)
        try {
            res.status(200).send();
        } catch (err) {
            console.error(err);
            res.status(500).json({
                error: "Internal Server Error"
            });
        }
    }

    GET.apiDoc = {
        summary: "Retrieve data from the api",
        operationId: "get-test",
        responses: {
            200: {
                description: "Returns if it was able to connect to the service",
            },
            500: {
                description: "Internal Server Error",
                content: {
                    "application/json": {
                        schema: {
                            $ref: "#/components/schemas/Error",
                        },
                    },
                },
            },
        },
    };
    return operations;
};

I am following the guidelines mentioned in the express-openapi documentation to structure my path files and use the {id} syntax for URL parameters.

Interestingly, I can access the /test route without any issues. However, I am not able to access the /customer by itself. I receive a 404 error. When adding the /customer/{id} file I receive the error detailed above.

The error seems to be related to the path-to-regexp module, but I'm not directly using this module in my code. It's being used internally by express-openapi.

I suspect the issue is due to the {id} file name, which could be getting passed as a part of the path to the path-to-regexp function.

If you could help me understand what's causing this error and how I could resolve it, I would greatly appreciate it. Please let me know if you need any further information. If you know better ways to debug this code or get a better error message, please let me know.

Thank you for your time and assistance!

[Xander Endre]

Opened PR #869 to resolve this issue.

[renkei]

Opened another PR #877 that modifies fs-routes instead and fixes this issue and also #871

[Jan Mertens]

Still a problem over here - any workarounds yet?

[Anthony Loukinas]

I'm also still seeing this issue:

\node_modules\path-to-regexp\index.js:128
  return new RegExp(path, flags);
         ^
SyntaxError: Invalid regular expression: /^\/api\v1\users\(?:([^\/]+?))\/?$/: Unmatched ')'
    at new RegExp (<anonymous>)
    at pathtoRegexp (D:\Projects\REDACTED\REDACTED-api\node_modules\path-to-regexp\index.js:128:10)
    at new Layer (D:\Projects\REDACTED\REDACTED-api\node_modules\express\lib\router\layer.js:45:17)
    at Function.route (D:\Projects\REDACTED\REDACTED-api\node_modules\express\lib\router\index.js:505:15)
    at Function.app.<computed> [as get] (D:\Projects\REDACTED\REDACTED-api\node_modules\express\lib\application.js:498:30)
    at Object.visitOperation (D:\Projects\REDACTED\REDACTED-api\node_modules\express-openapi\index.ts:205:25)
    at D:\Projects\REDACTED\REDACTED-api\node_modules\openapi-framework\index.ts:605:19
    at Set.forEach (<anonymous>)
    at D:\Projects\REDACTED\REDACTED-api\node_modules\openapi-framework\index.ts:364:9
    at Array.forEach (<anonymous>)

I also have a similar structure where I'm using {id}.js. This issue only happens on Windows, my Mac/Linux workstations don't have these issues.

Package.json

"express-openapi": "^12.1.3"