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dojo/request/handlers

authors:Bryan Forbes
since:V1.8

dojo/request/handlers is a module that provides handlers that deal with the data that is returned in a response to a request.

Introduction

dojo/request/handlers provides handlers that will convert the response payload into a data object. By setting the handleAs option to a request, the returned promise will resolve to the resulting data object rather than the text of the response payload. The returned promise’s response property will resolve to an object with a data property that is converted data object. The standard handlers are:

  • json - Will attempt to parse the response as a JSON string.
  • javascript - The response will be assumed to be JavaScript and be eval()/ed.
  • xml - The response will be treated as XML.

dojo/request/handlers allows registration of custom handlers using the .register() function.

Usage

register()

Normally, dojo/request/handlers is not used directly, except when you want to register a new handler type. In that case, usage would look like this:

require([
  "dojo/request/handlers",
  "dojo/request"
], function(handlers, request){
  handlers.register("split", function(response){
    // Do something with response.text
    return response.text.split(",");
  });

  request("http://example.com/something", {
    handleAs: "split"
  }).then(function(data){
    // data contains an array of strings
  });
});

Whatever a handler returns, when used as the handler, will be what the returned promise resolves to and will be put into the data property of the object the response promise resolves to. The payload of the un-handled response is in the text property of the object the response promise resolves to.

.register() takes two arguments:

Argument Type Description
name String The name that will be matched when handleAs option is specified in a a request.
handler Function The function that handles the response and returns the converted object.

Examples

This example retrieves a JSON resource, which is set to be handled as json and outputs data, which will be a JavaScript object that has been converted from the JSON.

require(["dojo/request", "dojo/dom", "dojo/dom-construct", "dojo/json", "dojo/on", "dojo/domReady!"],
function(request, dom, domConst, JSON, on){
  on(dom.byId("startButton"), "click", function(){
    domConst.place("<p>Requesting...</p>", "output");
    request("./helloworld.json", {
      handleAs: "json"
    }).then(function(data){
      domConst.place("<p>data: <code>" + JSON.stringify(data) + "</code>", "output");
    });
  });
});

<h1>Output:</h1>
<div id="output"></div>
<button type="button" id="startButton">Start</button>

This example retrieves an XML resource, which is set to be handled as xml and outputs data, which will be an XML document object created from the XML text.

require(["dojo/request", "dojo/dom", "dojo/dom-construct", "dojo/json", "dojo/on", "dojo/domReady!"],
function(request, dom, domConst, JSON, on){
  on(dom.byId("startButton"), "click", function(){
    domConst.place("<p>Requesting...</p>", "output");
    request("./helloworld.xml",{
      handleAs: "xml"
    }).then(function(xmldoc){
      domConst.place("<p>xmldoc: <code>" + JSON.stringify(xmldoc) + "</code>", "output");
    });
  });
});

<h1>Output:</h1>
<div id="output"></div>
<button type="button" id="startButton">Start</button>

This example retrieves a JavaScript resource, which is set to be handled as javascript and outputs data, which will be the result of calling eval() in the global scope on the text of the response.

require(["dojo/request", "dojo/dom", "dojo/dom-construct", "dojo/json", "dojo/on", "dojo/domReady!"],
function(request, dom, domConst, JSON, on){
  on(dom.byId("startButton"), "click", function(){
    domConst.place("<p>Requesting...</p>", "output");
    request("./helloworld.js",{
      handleAs: "javascript"
    }).then(function(data){
      domConst.place("<p>data: <code>" + JSON.stringify(data) + "</code>", "output");
    });
  });
});

<h1>Output:</h1>
<div id="output"></div>
<button type="button" id="startButton">Start</button>

This example registers a custom handler and requests a resource that will be handled by the custom handler.

require(["dojo/request/handlers", "dojo/request", "dojo/dom", "dojo/dom-construct", "dojo/json",
    "dojo/on", "dojo/domReady!"],
function(handlers, request, dom, domConst, JSON, on){
  handlers.register("custom", function(response){
    var data = JSON.parse(response.text);
    data.hello += "!";
    return data;
  });

  on(dom.byId("startButton"), "click", function(){
    domConst.place("<p>Requesting...</p>", "output");
    request("./helloworld.json", {
      handleAs: "custom"
    }).then(function(data){
      domConst.place("<p>data: <code>" + JSON.stringify(data) + "</code>", "output");
    });
  });
});

<h1>Output:</h1>
<div id="output"></div>
<button type="button" id="startButton">Start</button>

See also

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