Imported interface behaves differently from localy available interface

[ackvf]

TypeScript Version: 2.9.0-dev.20180511

Code

// types.d.ts
export interface MyImportedItem {
  id: number
  another: string
  param1: string
}


// firebase.actions.ts

interface MyItem {
  id: number
  another: string
  param1: string
}

getFirebaseRef().push({ // error
  id,
  another: data.another,
  param: data.someValue,
  // param2: 'X',
} as MyItem)

getFirebaseRef().push({ // no error
  id,
  another: data.another,
  param: data.someValue,
  // param2: 'X',
} as MyImportedItem)

Error:

Type '{ id: any; another: any; param: any; }' cannot be converted to type 'MyItem'.
      Property 'param1' is missing in type '{ id: any; another: any; param: any; }'.

Expected behavior:
Expected is consistent behavior for local and imported interface.
Expected is that missing and invalid props are correctly reported by the IDE.

Actual behavior:

[RyanCavanaugh]

I see an error in your second call - there's a red squiggle on id

[ackvf]

That is unrelated, I fixed it, id was not defined. When I swap the two interfaces, the error moves, so it is indeed tied to that particular interface.

[mhegazy]

Can u share a self contained repro for us to look at?

[ackvf]

I take it back, I had MyImportedItem imported twice, not sure how that happened. Anyway, I still have one issue regarding "Expected is that missing and invalid props are correctly reported by the IDE.": I don't get errors when my object is not complete or contains invalid keys, but I do get error that a key (param1) is missing if I introduce another key (param2) that is not part of the interface.

No error

Error param1 is missing

---

Moreover, can somebody please explain to me why the const declaration here gives an error correctly, while using it with as in the push does not?

Here I get that param1 is missing in the push.

---

I am using it like this so that I get hints for the object I am pushing.

Is there a better approach to get hints but avoid declaring the object beforehand? Thank you

[mhegazy]

@ackvf it is very hard to debug issues like that using screenshots.. we would appreciate it if you would include a self-contained code sample that provides a reproduction of the issue you are facing..

[ackvf]

I am sorry, I included the code at the top and I thought that it is self-contained enough. My repo is just an experimental repo with so few files that I did not think they would affect the behaviour of the snippet in any way. Anyway, my first issue was due to a mistake in code and my second issue (that from my last comment 2 days ago) was more like a question than an issue. I thought that it is actually behaving correctly but in a way I was not aware of.

This is really it...

interface MyItem {
  another: string
  id: number
  param1: string
}

const getFirebaseRef = (): any => void


getFirebaseRef().push({ // no error here that param1 is missing
  another: 'another',
  id: 42,
  // param1: 'param1',
  // param2: 'X',
} as MyItem)

const myItem: MyItem = { // error param1 is missing
  another: 'another',
  id: 42,
  // param1: 'param1',
  // param2: 'X',
}

getFirebaseRef().push(myItem)

interface MyItem {
  another: string
  id: number
  param1: string
}

const getFirebaseRef = (): any => void


getFirebaseRef().push({ // error param1 is missing
  another: 'another',
  id: 42,
  // param1: 'param1',
  param2: 'X', // no error for param2
} as MyItem)

const myItem: MyItem = { // no error that param1 is missing
  another: 'another',
  id: 42,
  // param1: 'param1',
  param2: 'X', // error may only specify known properties
}

getFirebaseRef().push(myItem)

[ackvf]

My question was if it is possible to get hints for the pushing object without having to declare the object beforehand.

I am looking for something like this - to specify the type of the inline object I am pushing

so that when I ctrl+space I get hints and warnings, but instead I do get hints, but no warnings.

[ackvf]

Obviously, I cannot use this to specify that the object I am pushing is MyItem getFirebaseRef().push({}: MyItem) // parsing error: ',' expected

Using type casting also -by nature- does something else than I want, so if there was something like type guards for inline objects/values, that would be great:

getFirebaseRef().push({} is MyItem)
-> now I get hints for object properties
-> now I get errors for missing and unknown properties

[RyanCavanaugh]

@ackvf #7481