How to bind JSON object key value pair separately to angular template

问题

And i have a dynamic json coming from an API as below:

 {123: "Mumbai", 456: "Bangalore", 789: "Chennai", 101: "Andhra",...}

I have below HTML code written in my template in which I am getting image-1, image-2 logos from my assets folder

  <div class="row">
    <div class="col-6" (click)="cityClick('Bangalore')">
      <div class="img-1">
        // my image-1 logo goes here
      </div>
      <div class="img-text">
        Bangalore
      </div>
    </div>
    <div class="col-6" col-6 (click)="cityClick('Mumbai')">
      <div id="image_block" class="img-2">
        // my image-2 logo goes here
      </div>
      <div id="text_block" class="img-text">
        Mumbai
      </div>
    </div>
  </div>

How to get the key of the json when i click on image and also display the text below the image from the corresponding key-value. And when i click i should be able to pass the key and text inside the click event. Please help as i am new to Angular!

回答1:

First convert this JSON into an JavaScript/TypeScript array like below:

var json = {123: "Mumbai", 456: "Bangalore", 789: "Chennai", 101: "Andhra" };

var jsonToBeUsed = [];

for (var type in json) {
    item = {};
    item.key = type;
    item.value = json[type];
    jsonToBeUsed.push(item);
}

This will result in data like below:

Now use NgFor in the template to bind array. (Refer this for NgFor)

<div class="row">
    <div *ngFor="let item of array">
         <div class="col-6" (click)="cityClick(item)">
              <div class="img-1">
                // my image-1 logo goes here
              </div>
              <div class="img-text">
                {{item.value}}
              </div>
        </div>
    </div>
</div>

We have passed the whole object in the click event. You can read any of the desired property from the object in click event handler which you will write in the component.

For your special requirement, you can use below markup:

<div class='row' *ngFor='let index of array; let i = index; let even = even'>
    <div *ngIf="even" class='col-6' (click)="cityClick(array[i])">
        <div class="img-1">
            // my image-1 logo goes here
        </div>
        <div class="img-text">
            {{array[i].value}}
        </div>
    </div>
    <div *ngIf="!even" class='col-6' (click)="cityClick(array[i])">
        <div class="img-1">
            // my image-1 logo goes here
        </div>
        <div class="img-text">
            {{array[i].value}}
        </div>
    </div>
</div>

回答2:

Use this below function in your code:

getKeyByValue(object, value) {
      return Object.keys(object).find(key => object[key] === value);
}

And use as

var dynamicJson = {123: "Mumbai", 456: "Bangalore", 789: "Chennai", 101: "Andhra"}

cityClick(value){
      var key = this.getKeyByValue(this.dynamicJson, value);
      console.log(key);
}

回答3:

{123: "Mumbai", 456: "Bangalore", 789: "Chennai", 101: "Andhra",...}

Do you have influence on that JSON? This highly looks like a design issue for me. I assume those numbers are id's. I believe somethings like this should be better:

[{id: "123", name: "Mumbai"}, {id: "456", name: "Bangalore"}, {id: "789", name: "Chennai"}, {id: "101", name: "Andhra"},...}]

In that case you receive an array of cities, which could be an interface to parse to.

export interface City {
   id: string;
   name: string;
} 

And you can easily render it in html by using *ngFor

<div *ngFor="let city of cities">
     <!--do something with city.id and city.name-->
   </div>

回答4:

<div *ngFor let value of json |keyvalue > </div>

来源：https://stackoverflow.com/questions/54804675/how-to-bind-json-object-key-value-pair-separately-to-angular-template