Event context can be undefined according to type definitions

[0x80]

According to the 1.0.0 Typescript definitions the context part of an event is defined as EventContext | undefined. For example:

const myFunction = firestore
  .document(`collection/{documentId}`)
  .onCreate((data, context) => {
    // Check if context is defined?
  });

I have a hard time imagining why this would ever be undefined, so I am currently ignoring it.

Context as the second parameter to the handler function is optional, because you can supply a handler with just the data argument. But shouldn't that be solved via overloading? If I supply a function with both arguments then context should be guaranteed to exist, no?

[laurenzlong]

Could you copy and paste the exact line, and from which .d.ts you are referring to?

[0x80]

Hi @laurenzlong, vcode points me to

firebase-functions/lib/providers/firestore.d.ts line 22:

    onCreate(handler: (snapshot: DocumentSnapshot, context?: EventContext) => PromiseLike<any> | any): CloudFunction<DocumentSnapshot>;

So here the context argument is optional, and as a result TSC forces you to check its existence inside the handler function. I think this would be better solved with an overload for onCreate to allow both 1 and 2 args handlers.

[laurenzlong]

@0x80 Thanks for the additional info. I'm not able to reproduce the issue on my end. Is it a linter error or an actually TypeScript compiler error you're getting? Do you get the error when you run "tsc"?

What's your typescript version and tsconfig.json?

[0x80]

It is a compiler error, and it should be given the signature I think. Maybe you didn't use strict compiler settings?

I'm using Typescript 2.8 and this is my config:

{
  "compilerOptions": {
    "target": "ES2016",
    "module": "commonjs",
    "lib": ["esnext"],
    "sourceMap": true,
    "outDir": "build",
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "noImplicitThis": true,
    "alwaysStrict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "moduleResolution": "node",
    "plugins": [
      {
        "name": "tslint-language-service"
      }
    ]
  },
  "include": ["src/**/*"]
}

[merlinnot]

It's just defined like this in the source code, unnecessarily AFAIK. I've made a PR yesterday.

[uloga]

Typescript version 3.2.2, latest firebase - functions getting the same lint errors while following documentation on firebase. :(

[mon2104]

Latest firebase, if we use
import {EventContext} from 'firebase-functions'
gives error -- cannot import from outside a module.
How to fix it ?