ajaxJson

This function provides an easy way to call an HTTP url that takes a JSON input and returns a JSON response. The method automatically parses a parameter object to JSON and result JSON into a result object or value.

You can pass a value or object that is turned into JSON which by default is POST'ed to the server. If no parameter is provide the request defaults to a GET operation. You can override the verb via the options.verb parameter. You can also use the options.noPostEncoding option to prevent JSON encoding of parameters.

The result is handled either via the two callback parameters for success and error respectively:

JSON Object or value (just pass a value):

function CallServiceWithPromise()
{
    ajaxJson("timetrakkerservice.svc/LoadCustomer",
			{Pk:12,Entered:new Date()},{verb: PUT},
    		function (result)  { // parsed object instance
    		    alert( result.d.Company);
    		    alert( result.d.ProjectEntities[1].CustomerEntity.LastName);
    		},
    		function(error) {  // error object
                alert("Error: " + error.message); // parsed error
            });

Raw POST string:

function CallServiceWithCallbacks()
{
    ajaxJson("timetrakkerservice.svc/SaveCustomer",
			"Name=Rick&Company=West+Wind",
			Callback,onError,
			{ contentType: "application/x-www-urlencoded", noPostEncoding: true});
}
function Callback(result)
{
    alert( result.d.Company);
    alert( result.d.ProjectEntities[1].CustomerEntity.LastName);
}
function onError(error)
{
    alert("Error: " + error.message);
}

ajaxJson() automatically uses application/json by default for the Content-Type and Accept headers in the request. If you need to send or receive data of a different type be sure to explicitly set the Headers

Note that if passing a string you should pass the content type explicitly - otherwise the string will be posted as JSON.

If you are calling a CallbackHandler or AjaxMethodCallback control on the server use the ajaxCallMethod function instead.

Setting custom headers

If you need to send custom headers you can you use the options parameter. There are a number of common preset properties you can set on this options object that affect the HTTP object's behavior, or you can directly add headers as key value pairs:

ajaxJson("/timetrakkerservice.svc/SaveCustomer",
	"Name=Rick&Company=West+Wind", // url-encoded form data
	Callback,onError,
	{  // options
	
	  // built-in props
	  contentType: "application/x-www-urlencoded", 
	  noPostEncoding: true,
	  
	  // explicit custom headers
	  headers: {
	      "security-header": "custom value",
	      "keep-alive": -1
	  }
    });
ajaxJson(url,value,callback,errorCallback,options)

Return Value

raw jquery.ajax promise - don't use the promise unless you need to have access to the raw HTTP response.

Parameters

url
The URL to access including any query string data.

value
a single value or array that is passed to the server. For MS Ajax pass an object with a property for each parameter. For Web Connection pass an array of values one for each parameter.

If this value is null a GET request is sent. If options don't override behavior a POST request is sent when data is provided.

callback
Optional function that is called on a successful callback. Function receives raw HTTP result string as a parameter.

errorCallback
Optional function that is called when an error occurs. Receives a CallbackException object as a parameter that holds exception information.

options
An optional object map that configures the HTTP operation based on settings of the HttpClient class. If the callBack and errorCallback functions are not provided options can be passed as the 3rd parameter.

Values:

  • accepts - accept header content type (application/json)
  • contentType - request content type (application/json)
  • noPostEncoding - don't turn parameter to JSON (false)
  • evalResult - don't turn result to JSON (true)
  • isMsAjaxJson - for MS AJAX style calls (false)
  • method - HTTP Verb (POST or GET depending on content)
  • timeout - request timeout
  • headers - object map of custom headers ( )

See also:

Using CallbackHandler with REST Calls | ajaxCallMethod

© West Wind Technologies, 1996-2020 • Updated: 08/21/20
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