Polymer - Iron Ajax

The <iron-ajax> element is useful in making ajax calls.

<iron-ajax
   auto url = "https://www.googleapis.com/youtube/v3/search"
   params = '{"part":"snippet", "q":"polymer", "key": "YOUTUBE_API_KEY", "type": "video"}'
   handle-as = "json"
   on-response = "handleResponse"
   debounce-duration = "500">
</iron-ajax>

When you set auto to true, a request is made by an element when its properties url, params, or body are changed. As you can see, the component has several attributes available −

url − An attribute where you place the url to the API endpoint.
params − An attribute where you can pass the JSON with the request parameters.
handle-as − Specifies what data must be stored in the response property. By default, the data is stored in the json format.
on-response − An attribute which can tell the iron-ajax component by what method the response is handled.

Changing multiple attributes sequentially causes automatically generated requests to be debounced.

You can call generateRequest on the element to trigger a request explicitly.

Example

In the following example, we have a link to the iron-ajax and paper-input components used from the CDN.

<!DOCTYPE html>
<html>
   <head>
      <title>iron-ajax</title>
      <link rel = "import"
         href = "https://cdn.rawgit.com/download/polymer-cdn/1.0.1/lib/paper-input/paper-input.html">
      <link rel = "import"
         href = "https://cdn.rawgit.com/download/polymer-cdn/1.0.1/lib/iron-ajax/iron-ajax.html">
   </head>
	  
   <body>
      <dom-module id = "data-bind">

         <template>
            <paper-input label = "Write something..." id = "input" value = "{{q::input}}"
               autofocus>
            </paper-input>
            <p>You typed: <b>{{q}}</b></p>
            <p>Echo: <b>{{echo}}</b></p>
           
            <iron-ajax auto
               url = "http://dict.leo.org/dictQuery/m-query/conf/ende/query.conf/strlist.json"
               params = "{'q': q}" handle-as = "json" on-response = "_handleResponse"
               debounce-duration = "500">
            </iron-ajax>
         </template>
       
         <script>
            (function () {
               Polymer ({
                  is: 'data-bind', properties: {
                     echo: {
                        type: String, value: 'waiting ...', reflectToAttribute: true
                     }
                  },
                  _handleResponse: function(event, request) {
                     var response = request.response;
                     this.echo = JSON.stringify(response);
                  }
               });
            })();
         </script>
      </dom-module>
    
      <data-bind></data-bind>
   </body>
</html>

Output

To run the application, navigate to your project directory and run the following command −

polymer serve

Now open the browser and navigate to http://127.0.0.1:8081/. Following will be the output.

polymer_elements.htm