Searching through a Typescript array in an Angular HTML component using a specific key

Question

Searching through a Typescript array in an Angular HTML component using a specific key

Recently, I embarked on my journey with Angular 2 and TypeScript.

My goal is to display data in a table. Specifically, I want to showcase one of the values as a name instead of an Id (a key) referencing another table.

In my quest for a solution, I stumbled upon a helpful thread on Stack Overflow discussing how to achieve this in TypeScript: Querying Typescript array collection based on key.

I followed the first answer provided and implemented it in my HTML component:

<div class="col-md-1">{{codeTypes.find(c => c.codeTypeId == level.codeType)[0].name}}</div>

However, I encountered a syntax error involving {{. Removing {{ and }} resulted in only displaying the code snippet in the HTML:

codeTypes.find(c => c.codeTypeId == level.codeType)[0].name

The codeTypes variable is a public property within my TypeScript class:

public codeTypes: ICodeType[];

The interface ICodeType is defined as follows:

export interface ICodeType {
    codeTypeId: number;
    name: string;
}

My objective is to query the codeTypes array, find the matching codeTypeId, and display its corresponding name in the HTML component. How can I achieve this?

angular typescript

Answer 1

Answer №1

Angular template syntax does not support the same functionality as JavaScript due to being a subset of it; specifically lambdas are restricted to prevent collision with interpolation syntax. Instead of trying to use lambdas in the template, consider using a Pipe or calling a method from your Component's class for querying. I highly recommend utilizing Pipes.

Here's an example using a method:

queryArray() {
   return this.codeTypes.find(c => c.codeTypeId == this.level.codeType)[0].name
}

In your HTML:

<div class="col-md-1">{{ queryArray() }}</div>

Answer 2

Angular template syntax does not support the same functionality as JavaScript due to being a subset of it; specifically lambdas are restricted to prevent collision with interpolation syntax. Instead of trying to use lambdas in the template, consider using a Pipe or calling a method from your Component's class for querying. I highly recommend utilizing Pipes.

Here's an example using a method:

queryArray() {
   return this.codeTypes.find(c => c.codeTypeId == this.level.codeType)[0].name
}

In your HTML:

<div class="col-md-1">{{ queryArray() }}</div>

Answer 3

Answer №2

To achieve this functionality, utilize pipes in your Angular application.

Here is the HTML structure:

<table class="table table-responsive table-hover">
 <tr>
  <th>District</th>
 </tr>
 <tr *ngFor="let item of records | slice:0:5 | category: searchText">
  <td>{{item.DistrictName}}</td>
 </tr>
</table>
<input type="text" [(ngModel)]="searchText" class="form-control"
placeholder="Search By Id" />

Implement the category.pipe.ts file:

import { Pipe, PipeTransform } from '@angular/core';
@Pipe({ name: 'category' })

export class CategoryPipe implements PipeTransform {
  transform(categories: any, searchText: any): any {
    if(searchText == null) return categories;

    return categories.filter(
      function(category){
       return category.id.toLowerCase().indexOf(searchText.toLowerCase()) > -1;
      }
    )
  }
}

Include the pipe in your TypeScript file:

import {CategoryPipe} from './category.pipe';


and then
export class CheckListComponent implements OnInit {
records: Array<any>;
this.records= [
{ DistrictName: "Ariyalur", id: "1" },
{ DistrictName: "Chennai", id: "2" },
{ DistrictName: "Coimbatore", id: "3" },
{ DistrictName: "Cuddalore",  id: "4" },
{ DistrictName: "Dharmapuri", id: "5" },
{ DistrictName: "Dindigul", id: "6" },
{ DistrictName: "Erode", id: "7" },
];

Lastly, declare the pipe in app.module.ts:

import {CategoryPipe} from './category.pipe';


@NgModule({
declarations: [
AppComponent,
CategoryPipe
],

Answer 4

To achieve this functionality, utilize pipes in your Angular application.

Here is the HTML structure:

<table class="table table-responsive table-hover">
 <tr>
  <th>District</th>
 </tr>
 <tr *ngFor="let item of records | slice:0:5 | category: searchText">
  <td>{{item.DistrictName}}</td>
 </tr>
</table>
<input type="text" [(ngModel)]="searchText" class="form-control"
placeholder="Search By Id" />

Implement the category.pipe.ts file:

import { Pipe, PipeTransform } from '@angular/core';
@Pipe({ name: 'category' })

export class CategoryPipe implements PipeTransform {
  transform(categories: any, searchText: any): any {
    if(searchText == null) return categories;

    return categories.filter(
      function(category){
       return category.id.toLowerCase().indexOf(searchText.toLowerCase()) > -1;
      }
    )
  }
}

Include the pipe in your TypeScript file:

import {CategoryPipe} from './category.pipe';


and then
export class CheckListComponent implements OnInit {
records: Array<any>;
this.records= [
{ DistrictName: "Ariyalur", id: "1" },
{ DistrictName: "Chennai", id: "2" },
{ DistrictName: "Coimbatore", id: "3" },
{ DistrictName: "Cuddalore",  id: "4" },
{ DistrictName: "Dharmapuri", id: "5" },
{ DistrictName: "Dindigul", id: "6" },
{ DistrictName: "Erode", id: "7" },
];

Lastly, declare the pipe in app.module.ts:

import {CategoryPipe} from './category.pipe';


@NgModule({
declarations: [
AppComponent,
CategoryPipe
],

Searching through a Typescript array in an Angular HTML component using a specific key

Answer №1

Answer №2

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