Reading Object returns undefined Angular 4

Question

 Arr1 [
    {id: 300,
    uploads: [
        {idOne: value},
        {idTwo: value}
       ]
    },
    {blah: value, 
     uploads: [
        {idOne: value},
        {idTwo: value}
       ]
    }
]

This Object is being read like this

 this.activatedRoute.parent.params
      .switchMap((params: Params) => this.someService.getSubmissions(+params['id']))
      .subscribe(submissions => console.log('subs', submissions.map(x=>x)))

results in

The Object as shown above.

And

 this.activatedRoute.parent.params
      .switchMap((params: Params) => this.someService.getSubmissions(+params['id']))
      .subscribe(submissions => console.log('subs', submissions.map(x=>x.id)))

Displays id:300

But when I go

 this.activatedRoute.parent.params
      .switchMap((params: Params) => this.someService.getSubmissions(+params['id']))
      .subscribe(submissions => console.log('subs', submissions.map(x=>x.uploads)))

It logs undefined. And I can not reasonably detect why.

This is within the onInit() of an Angular component.

Also, `myObjectName` is an array. It seems to contains some objects. Do those objects all have `uploads` property ? — Serge K., Jan 22 '18 at 11:07
to be able to .map(x=>x.id), as submissions.id is not working. — Fabioo Fabiulous, Jan 22 '18 at 11:08
You should read [`map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map) documentation. `.map(x => x)` will copy your array, which is useless in your case since you call `map` a second time. Also, given the pseudo-code you provided, no, `uploads` is _NOT_ inside all your objects. — Serge K., Jan 22 '18 at 11:10
@FabiooFabiulous do not write `(params: Params) => ...`. it is dangerous. Also the identity mapping is nonsense as Serge K already noted. — Aluan Haddad, Jan 22 '18 at 11:10
@Jota.Toledo imagine that `params` is typed as `Observable`. If so, any annotation on `params` will pass the type checker since `any` is assignable to and from any other type. This will mislead the reader since it reads as if the `Observable` has a meaningful element type (just redundantly overspecified) but in reality it is acting like a type assertion. An explicit type assertion is much better practice. — Aluan Haddad, Jan 22 '18 at 11:17
Possible duplicate of [From an array of objects, extract value of a property as array](https://stackoverflow.com/questions/19590865/from-an-array-of-objects-extract-value-of-a-property-as-array) — Serge K., Jan 22 '18 at 13:08

score 0 · Answer 1 · answered Jan 22 '18 at 11:27

0

Try this, updated the above with forEach:-

this.activatedRoute.parent.params.switchMap(params => {
 this.someService.getSubmissions(+params['id']))
 .subscribe(submissions => {
   submissions.forEach(x=>{
      if(x.id){
        console.log("id",x.id);
      }
      if(x.uploads){
      console.log("uploads",x.uploads);
      }

    })
 });
});

answered Jan 22 '18 at 11:27

crystalthinker

1,200
15
30

The ID's are logged. The Uploads not. – Fabioo Fabiulous Jan 22 '18 at 12:03
@FabiooFabiulous If `uploads` aren't logged in this case, then `submissions` is not defined as you stated. – Serge K. Jan 22 '18 at 13:10

Reading Object returns undefined Angular 4

1 Answers1