@feathersjs/express^5 has a reused Symbol() across pkgs, but not actually equal #3071
Description
Steps to reproduce
- Build a small Express based app with v5.
- Modify the package.json to leverage aliases for v5 express and v5 core.
"dependencies": {
"f5": "npm:@feathersjs/feathers@^5.0.0-pre.38",
"f5_exp": "npm:@feathersjs/express@^5.0.0-pre.38"
}- Modify your app imports to use the aliases:
const feathers = require('f5');
const express = require('f5_exp');- Send a request to your sample service.
- See 500 error:
TypeError: Cannot read properties of undefined (reading 'express')
at /Users/neptune/Sites/personal/tester/node_modules/f5_exp/lib/rest.js:51:36
at /Users/neptune/Sites/personal/tester/node_modules/f5_exp/lib/rest.js:12:32
at Layer.handle [as handle_request] (/Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/layer.js:95:5)
at trim_prefix (/Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/index.js:328:13)
at /Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/index.js:286:9
at Function.process_params (/Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/index.js:346:12)
at next (/Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/index.js:280:10)
at /Users/neptune/Sites/personal/tester/node_modules/f5_exp/lib/authentication.js:16:20
at /Users/neptune/Sites/personal/tester/node_modules/f5_exp/lib/authentication.js:8:32
at Layer.handle [as handle_request] (/Users/neptune/Sites/personal/tester/node_modules/f5_exp/node_modules/express/lib/router/layer.js:95:5)
Possible Root Cause
The error is caused by an empty options object here:
feathers/packages/express/src/rest.ts
Lines 65 to 66 in 4fbbfff
This is returned by the
getServiceOptions function, which is pretty straightforward:feathers/packages/feathers/src/service.ts
Lines 38 to 40 in 4fbbfff
It does a property check on the service for a SYMBOL('@feathersjs/service').
When I inspect in debugger, the data is there, but the SYMBOL is different from what was set as a property and what is being checked.
I've tried legacy bundling, but that didn't work either. I suspect that the SYMBOL is being created in different contexts, and therefore doesn't reference the same object. Seems like there's a dependency injection/inversion here from the express lib that could resolve this, but I don't fully understand the benefit of the SYMBOL usage.
Any guidance?
How this was discovered.
I'm trying to setup automated testing across multiple Feathers libraries that currently work in 4 and need to be extended to 5. Creating multiple branches for testing felt like an ugly solution since it would require a lot of pipeline revisions and tie the semVer of the library to the Feathers versions. I explored npm overrides, npm aliases, and legacy-bundling=true to see if I could deduce the reason the SYMBOL was different in the express function.
Expected behavior
Dove Express should return a normal response even when aliasing the libraries.
Actual behavior
Dove Express throws an error related to unreferenced SYMBOL
System configuration
Tell us about the applicable parts of your setup.
Module versions
@feathersjs/feathers@^5.0.0-pre.38
@feathersjs/express@^5.0.0-pre.38
NodeJS version:
- 16 & 18
Operating System:
- OSX
Browser Version:
- n/a
React Native Version:
- n/a
Module Loader:
- CommonJS