I want to show different different values from JSON data depending on a drop down selection.

<div>
    <label for="input-one">select</label>
</div>
<div>
    <select>
        <option value="">--- Select ---</option>
        <option value="1">option1</option>
        <option value="2">option2</option>
        <option value="3">option3</option>
    </select>
</div>

This is the drop down selection. What is the best approach to show the JSON data based on a selection?

For example:

• If you select 1, it should show 2 values from JSON data.
• If you select 2, it should show 3 values from JSON data.
• If you select 3, it should show all JSON data.

I want to do this in Angular 2. Please suggest me what could be the solution.

I want to show different different values from JSON data depending on a drop down selection.

<div>
    <label for="input-one">select</label>
</div>
<div>
    <select>
        <option value="">--- Select ---</option>
        <option value="1">option1</option>
        <option value="2">option2</option>
        <option value="3">option3</option>
    </select>
</div>

This is the drop down selection. What is the best approach to show the JSON data based on a selection?

For example:

• If you select 1, it should show 2 values from JSON data.
• If you select 2, it should show 3 values from JSON data.
• If you select 3, it should show all JSON data.

I want to do this in Angular 2. Please suggest me what could be the solution.

• javascript
• json
• angular
• typescript
• angular2-forms

1 Answer 1

Hello_ Sakura chan :)

I'm not sure that I fully understand your question, but I did understand that you want to show items filtered by <select>. If this is the case I can suggest you to use:

• Event binding
• Custom Pipe

Shortly about Event Binding ********************************

Basically with Event binding you are handling element event like this:

<select (change)="onMySelectChange($event)"></select>

Now inside onMySelectChange you can filter your collection depending on the value of the <select>

Shortly about Custom Pipe ********************************

Here you make your filter in external file for example - myfilter.ts and then you need to implement interface PipeTransform with the function transform(value: any, ...args: any[]) : any.

Sample pipe would look like:

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
    name: 'myfilter'
})
export class MyFilterPipe implements PipeTransform {
    transform(items: any[], filter: Object): any {

        if(filter == 1){
          return items.slice(0, 2);
        }else if(filter == 2){
          return items.slice(0, 3);
        }else if(filter == 3){
          return items;
        }else{
          return [];
        }
    }
}

and sample usage would be:

<ul>
    <li *ngFor="let d of pipeFilterData | myfilter: 2">{{d.value}}</li>
</ul>

Don't forget to put your pipe in declarations of your app module:

@NgModule({
  imports: [ BrowserModule, FormsModule ],
  declarations: [ App, MyFilterPipe ],
  bootstrap: [ App ]
})

CLICK HERE TO DIG INTO DEMO CODE