Encountering an error with the Typescript 'any' type in Ionic 2

Question

Encountering an error with the Typescript 'any' type in Ionic 2

I need help understanding an error I encountered:

EXCEPTION: Error: Uncaught (in promise): EXCEPTION: Error in build/pages/search/search.html:17:14 
ORIGINAL EXCEPTION: Cannot find a differ supporting object 'function () {
    return [
        {
            "wrapperType": "track",
            "kind": "song",
            "artistId": 5869117,
            "collectionId": 459904774,
            ...
 at ViewRef_.detectChanges (http://localhost:8100/build/js/app.bundle.js:30401:65) ERROR CONTEXT [object Object]

Here is the code I am working with:

search.ts and search.html

I suspect the issue may be related to the type declaration of itemResults as any, even though I have specified it as any. This is an ionic 2 application with typescript, so any guidance to resolve this error would be greatly appreciated.

typescript angular ionic2

Answer 1

Answer №1

It seems like what you were trying to say is:

let data = fetchData();//make sure to include the parentheses when calling the function.

Consider using the $onInit lifecycle hook instead of the constructor

$onInit(){
  let data = fetchData();
}

The constructor should only be used for initializing variables, not for loading data or causing any side effects.

Answer 2

It seems like what you were trying to say is:

let data = fetchData();//make sure to include the parentheses when calling the function.

Consider using the $onInit lifecycle hook instead of the constructor

$onInit(){
  let data = fetchData();
}

The constructor should only be used for initializing variables, not for loading data or causing any side effects.

Answer 3

Answer №2

When you write

this.itemResults = this.getResults;

without the parentheses, you are actually assigning a function object to the itemResults property. This is why the error message states:

Cannot find a differ supporting object 'function () { ... } of type 'function'. NgFor only supports binding to Iterables such as Arrays.

To fix this issue, you should change that line of code to

this.itemResults = this.getResults();

so that the method is executed and the result is assigned to the itemResults property.

Answer 4

When you write

this.itemResults = this.getResults;

without the parentheses, you are actually assigning a function object to the itemResults property. This is why the error message states:

Cannot find a differ supporting object 'function () { ... } of type 'function'. NgFor only supports binding to Iterables such as Arrays.

To fix this issue, you should change that line of code to

this.itemResults = this.getResults();

so that the method is executed and the result is assigned to the itemResults property.

Encountering an error with the Typescript 'any' type in Ionic 2

Answer №1

Answer №2

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