ionic 2 "Type '{}' is not assignable to type 'any[]"

Question

There is an ionic 2 project.

Here is my code:

export class PostPage {
  posts : [any];

  constructor(private nav:NavController,
    private postSvc: PostService) {
  }

  ngOnInit() {    
    this.postSvc.load()
      .subscribe( data => {
          this.posts = data;
      });
  }

The error message is for this.posts = data. I defined this.posts as [any]. Also in my PostService I defined the data as [] too.

Code for PostService:

load() {
    return new Observable( observer => {

      var Post = Parse.Object.extend("Post");
      var query = new Parse.Query(Post);
      query.find({
        success: results => {
          var data = [];
          for (var i = 0; i < results.length; i++) {
            var object = results[i];
            var item = this.createPost(object);
            data.push(item);
          }
          observer.next(data);
          observer.complete();
        },
        error: error => {
          observer.error(error.message);
        }
      });
    });
  }

I got the error message:

Type '{}' is not assignable to type 'any[]

As you see, I call observer.next(data) where the data is []. I don't understand why my ionic 2 think my data is a '{}' . Any idea? Thanks.

Solution

For off posts : [any]; you probably meant posts : any[];

Type '{}' is not assignable to type 'any[]

This can happen if the TypeScript compiler cannot figure out the type by type inference e.g. if the inferred type is Promise<{}> the value passed to then will be of type {}.

Specify the type in:

return new Observable( observer => {

e.g:

return new Observable<any>( observer => {

Comments

[Robert]

For everybody coming here: In my case this solved it: return new Promise<any[]>(resolve => { ...