isTypeResolver issue with pre-compiled models.

[evantrimboli]

Steps to reproduce

Probably related to this TODO in the code:

// TODO(bajtos): support model classes defined via ES5 constructor function

As part of our build process, we generate the OpenAPI models (using lb4 openapi), build them and include them as a node package. During startup of the rest server generateOpenAPISchema() is called to generate JSON to work with the model definitions.

Inside isTypeResolver, it attempts to figure out if the function is a class or a resolver, by using /^class/.test(fn.toString(). In my case, this doesn't pass, fn.toString() evaluates to:

function MainFilters(data) {
    if (data != null && typeof data === 'object') {
        Object.assign(this, data);
    }
}

Obviously this is intended as an object constructor, but it's not detected. My current workaround is to check: if (fn.definition) return false; which seems to work ok.

Current Behavior

An exception is thrown by metaToJsonProperty.

Expected Behavior

An exception is not thrown.

Link to reproduction sandbox

Not able to provide a simple test, however I hope from the description that it makes sense.

Additional information

win32 x64 12.5.0

"@loopback/boot": "^1.5.10"
"@loopback/context": "^1.23.4"
"@loopback/core": "^1.10.6"
"@loopback/openapi-v3": "^1.10.0"
"@loopback/rest": "^1.22.0"
"@loopback/rest-explorer": "^1.4.3"
"@loopback/cli": "^1.24.0"

Related Issues

See Reporting Issues for more tips on writing good issues

[bajtos]

Here is the implementation of isTypeResolver with the TODO comment:

https://github.com/strongloop/loopback-next/blob/202b2c76b77122654ed81e60afcd2e2a2985de91/packages/repository/src/type-resolver.ts#L36-L52

Here is the thread where we discussed the problem of detecting ES5-style classes, it includes some ideas how to improve the detection too:

#1618 (comment)

@evantrimboli How difficult is it for you to upgrade your models from ES5 style to ES6 class? I would expect your example code to look like this:

class MainFilters{
  constructor(data) {
    if (data != null && typeof data === 'object') {
        Object.assign(this, data);
    }
  }
}

Is the ES5-style code generated by lb4 openapi? In that case I think we should change lb4 openapi to use ES6 or TypeScript.

Is this ES5 code created by your build step? If that's the case, then can you please change your compiler/transpiler to target ES6? I think es2017 is even better target - IIRC Node.js 8.x (the oldest LTS version) has full support for ES2017.

Here is a snippet of code from TypeScript output for our example Todo model - you can clearly see that it's using ES6 class syntax:

let Todo = class Todo extends repository_1.Entity {
    constructor(data) {
        super(data);
    }
};

[stale]

This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.