Accessing property values from a map in Angular

Question

Accessing property values from a map in Angular

Is there a way to retrieve a property from a map and display it in a table using Angular? I keep getting [object Object] when I try to display it. Even using property.first doesn't show anything.

//model

export interface UserModel { 
       room: Map<number,number> 
}


//service

export class UserService {
  user: UserModel;

  newUser: UserModel = {
    room: new Map<number,number>(),
....}}


//html
 <tbody>
      <tr *ngFor="let user of $users | async">
        <td>{{user.room}}</td> // user.room.first???
      </tr>
      
 </tbody>

Any suggestions would be greatly appreciated!

angular typescript

Answer 1

Answer №1

It seems like there may be some confusion about how to use *ngFor in this scenario. The *ngFor directive is typically used for iterating over arrays, not Maps. If your data type is a Map, you will need to convert it into an array in order to properly use *ngFor.

If you could provide more details about the desired end result, I may be able to offer a more tailored solution to your issue.

Based on my understanding, it appears that you are trying to display the values associated with each key in a table format.

In order to achieve this, you will need to convert the keys of the Map into an array. You can do this using the following code snippet:

this.keys = Object.keys(this.user)

Add this line to your .ts file, and then incorporate the following code into your HTML:

<tbody>
  <tr *ngFor="let key of keys | async">
    <td>{{user[key]}}</td>
  </tr>

By following these steps, you should be able to achieve your desired outcome. Let me know if you need any further assistance.

Answer 2

It seems like there may be some confusion about how to use *ngFor in this scenario. The *ngFor directive is typically used for iterating over arrays, not Maps. If your data type is a Map, you will need to convert it into an array in order to properly use *ngFor.

If you could provide more details about the desired end result, I may be able to offer a more tailored solution to your issue.

Based on my understanding, it appears that you are trying to display the values associated with each key in a table format.

In order to achieve this, you will need to convert the keys of the Map into an array. You can do this using the following code snippet:

this.keys = Object.keys(this.user)

Add this line to your .ts file, and then incorporate the following code into your HTML:

<tbody>
  <tr *ngFor="let key of keys | async">
    <td>{{user[key]}}</td>
  </tr>

By following these steps, you should be able to achieve your desired outcome. Let me know if you need any further assistance.

Answer 3

Answer №2

If you want to utilize a map in an Angular template, it is advisable to first convert it to an array or object.

getArray(map){
  return Array.from(map.keys());
}

Afterwards, you can easily access it within your Angular template.

  <tr *ngFor="let element of getArray(map)">
     <!-- element[0] is key && element[1] is value -->
    <td>{{element[0] - element[1]}}</td>
  </tr>

To improve efficiency, you can store the converted array in a variable as shown below.

public mapArray;
public map;

constructor() {
  this.map = new Map();
  this.mapArray = [];
}

public ngOnInit() {
  this.doSomeThing();
  this.convertMapToArray();
}

private doSomeThing(){
  this.map.set('my_key_1', 'my_value_1');
  this.map.set('my_key_2', 'my_value_2');
}

private convertMapToArray(){
  this.mapArray = Array.from(this.map.keys());
}

<tr *ngFor="let element of mapArray">
  <!-- element[0] is key && element[1] is value -->
  <td>{{element[0] - element[1]}}</td>
</tr>

Answer 4

If you want to utilize a map in an Angular template, it is advisable to first convert it to an array or object.

getArray(map){
  return Array.from(map.keys());
}

Afterwards, you can easily access it within your Angular template.

  <tr *ngFor="let element of getArray(map)">
     <!-- element[0] is key && element[1] is value -->
    <td>{{element[0] - element[1]}}</td>
  </tr>

To improve efficiency, you can store the converted array in a variable as shown below.

public mapArray;
public map;

constructor() {
  this.map = new Map();
  this.mapArray = [];
}

public ngOnInit() {
  this.doSomeThing();
  this.convertMapToArray();
}

private doSomeThing(){
  this.map.set('my_key_1', 'my_value_1');
  this.map.set('my_key_2', 'my_value_2');
}

private convertMapToArray(){
  this.mapArray = Array.from(this.map.keys());
}

<tr *ngFor="let element of mapArray">
  <!-- element[0] is key && element[1] is value -->
  <td>{{element[0] - element[1]}}</td>
</tr>

Accessing property values from a map in Angular

Answer №1

Answer №2

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