Angular datatable dropdown value in table showing blank and value appears and disappears instantly when going to next paginated page

Angular Datatable Dropdown Value Disappearing Issue

If you are experiencing an issue with an Angular datatable where the dropdown value in the table is showing blank and the value appears and disappears instantly when going to the next paginated page, you are not alone. This issue can be quite frustrating, but fortunately, there are a few solutions you can try to resolve it.

Solution 1: Use TrackBy Function

One possible cause of this issue is that the dropdown value is not being properly tracked by Angular’s change detection mechanism. To fix this, you can use the trackBy function in your datatable configuration.

Here’s an example of how you can implement this solution:

import { Component } from '@angular/core';

@Component({
  selector: 'app-datatable',
  templateUrl: './datatable.component.html',
  styleUrls: ['./datatable.component.css']
})
export class DatatableComponent {
  data: any[] = [
    { id: 1, name: 'John', selectedValue: 'Option 1' },
    { id: 2, name: 'Jane', selectedValue: 'Option 2' },
    { id: 3, name: 'Bob', selectedValue: 'Option 3' }
  ];

  trackByFn(index: number, item: any): number {
    return item.id;
  }
}

In the above example, we have added a trackByFn function that returns the unique identifier of each item in the datatable. This helps Angular to properly track the changes and prevent the dropdown value from disappearing.

Solution 2: Use ngAfterViewInit Lifecycle Hook

Another possible solution is to use the ngAfterViewInit lifecycle hook to delay the initialization of the dropdown value until the view has been fully initialized.

Here’s an example of how you can implement this solution:

import { Component, AfterViewInit } from '@angular/core';

@Component({
  selector: 'app-datatable',
  templateUrl: './datatable.component.html',
  styleUrls: ['./datatable.component.css']
})
export class DatatableComponent implements AfterViewInit {
  data: any[] = [
    { id: 1, name: 'John', selectedValue: 'Option 1' },
    { id: 2, name: 'Jane', selectedValue: 'Option 2' },
    { id: 3, name: 'Bob', selectedValue: 'Option 3' }
  ];

  ngAfterViewInit(): void {
    setTimeout(() => {
      // Initialize dropdown value here
    });
  }
}

In the above example, we have used the setTimeout function to delay the initialization of the dropdown value. This gives Angular enough time to properly render the datatable before initializing the dropdown.

By implementing one of these solutions, you should be able to resolve the issue with the dropdown value disappearing in your Angular datatable. Give them a try and see which one works best for your specific scenario.

Happy coding!