Issue: When attempting to read the length of a property in Angular 6, a TypeError is being thrown because the property is

Question

Issue: When attempting to read the length of a property in Angular 6, a TypeError is being thrown because the property is

Unable to retrieve values from an array using the TS code below:

this.dataservice.get("common/public/getAllCategories", null).subscribe(data => {
      //console.log('categories'+JSON.stringify( data));
   this.categoriesarray = data;
});
var data = this.items;
var categoriesdata = [];
for (var i = 0; i < data['categories'].length; i++) { // <- Error occurs on this line
    categoriesdata.push(data['categories'][i].categoryID);
    this.selspecialization = categoriesdata;
}
this.EditRequest = 'block';   
}

Here is my HTML snippet:

<button type="button" *ngIf="!userRechargeTable" class=" smallbtns btn roundButton btn-theme blue" (click)="edit()"> 
 Edit
</button>

angular typescript

Answer 1

Answer №1

Deciphering whether this block of code is intended to be one cohesive unit can be challenging due to the inconsistent variable and property names used. It seems likely that you may be attempting to process the results of an http request outside of the observable, before the data service has finished returning the data.

Have you considered trying the following approach?

this.dataservice.get("common/public/getAllCategories", null).subscribe(data => {
  //  //console.log('categories'+JSON.stringify( data));
  this.categoriesarray = data;
  // By moving this code inside the observable and using the map function, it has been optimized
  this.selspecialization = data['categories'].map(x => x.categoryID);
  this.EditRequest = 'block';
});

A few key changes have been made:

The code has been relocated inside the subscribe() method, ensuring it executes only after the observable (http request) completes and returns a value.
Your loop has been condensed into a single map function. The original for loop was redundant and unnecessarily reassigned this.selspecialization with each iteration.

Answer 2

Deciphering whether this block of code is intended to be one cohesive unit can be challenging due to the inconsistent variable and property names used. It seems likely that you may be attempting to process the results of an http request outside of the observable, before the data service has finished returning the data.

Have you considered trying the following approach?

this.dataservice.get("common/public/getAllCategories", null).subscribe(data => {
  //  //console.log('categories'+JSON.stringify( data));
  this.categoriesarray = data;
  // By moving this code inside the observable and using the map function, it has been optimized
  this.selspecialization = data['categories'].map(x => x.categoryID);
  this.EditRequest = 'block';
});

A few key changes have been made:

The code has been relocated inside the subscribe() method, ensuring it executes only after the observable (http request) completes and returns a value.
Your loop has been condensed into a single map function. The original for loop was redundant and unnecessarily reassigned this.selspecialization with each iteration.

Issue: When attempting to read the length of a property in Angular 6, a TypeError is being thrown because the property is

Answer №1

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