如何使用angular2 / typescript在过滤器下拉菜单中一次获得相同的名称

Question

I have a filter drop down in table1 which is present via table2 entries. In table2 if i have "Car" 2 times, den in filter dropdown also its showing 2 times Car, Car. How do i make it to come only once. Please help

HTML Code:

<div class="queryBox col-lg-2 col-md-2 col-sm-2 col-xs-3 taskDiv">
                <label>Vehice</label>
                <ng-select [options]="Vehice" [(ngModel)]="filter.vehice" class='filterDropDown' placeholder="All" [allowClear]="true">
                </ng-select>
            </div> 

Ts Code:

this.ApiService
                .getVehice  ()
                .subscribe(
                  vehicle  => {
                    this.Vehice = vehice.map(function(item) {
                      if(item.vehicle ) {
                        return {"value":item.vehice,"label":item.vehice};
                      }
                    })

Answer 1

I am not sure I would use a Pipe for filtering unique results. I would probably just do something like this:

let elements = [{'name' : 'Apple', 'type' : 1}, 
                {'name' : 'Apple', 'type' : 1}, 
                {'name' : 'Pear', 'type' : 4}];

function filterUniqueResults(list: any[]): any[]{
    let uniqueList = [];
    elements.forEach(element => {
       if(uniqueList.indexOf(element) === -1){
          uniqueList.push(element);
       }
    });
    return uniqueList;
}


let result = filterUniqueResults(elements);

Isn't it just this what you asked for?

From the code you posted it seems like you asked for something else instead, which is "how do I filter certain values given an attribute?" which you can do with a Pipe like this:

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

@Pipe({
    name: 'exclude'
})
@Injectable()
export class FilterPipe implements PipeTransform {
    transform(items: any[], field: string, value: string): any[] {
        if (!items) return [];
        return items.filter(it => it[field] != value);
    }
}

and then

<li *ngFor="let item of items | exclude : 'type' : 4">{{item.name}}</li>

or

<li *ngFor="let item of items | exclude : 'name' : 'apple'">{{item.name}}</li>

EDIT So to answer you comment:

this.apiService.getVehicles().subscribe(
                  result => this.vehicles  = filterUniqueResults(result));

given your apiService looks like this:

public getVehicles(): Observable<Vehicle[]> {
       return this.http.get("http://whatever")
            .map(res => res.json().data || {})
            .catch(error => console.error(error));
    }

Answer 2

    var valArray: any = [];

    function functionName(id){
    var idx = this.valArray.indexOf(id);

            if (idx > -1) {
                this.valArray.splice(idx, 1);
            }

            else {
                this.valArray.push(id);
            }
        }

In valArray array you will get the unique records.