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CefSharp - Get result of AJAX request

I am really new to CefSharps Chromium browser and have difficulty figuring out how to get the result of a jquery ajax request.
My first attempt was to pass my AJAX requesto to EvaluateScriptAsync. In fact the script works. It does exactly what I want, but I do not get any results/status codes, because my Cef-Task does not wait until AJAX has completed its work.
Here an example (just a sample code):
var tasks = pdBrowser.EvaluateScriptAsync(#"
(function(){
$.ajax({
type: ""POST"",
dataType: ""json"",
cache: false,
url: ""_resources/php/ajaxRequests.php"",
async: false,
data: {
action: ""insertCrossPlatform"",
type: """",
values: JSON.stringify(""foo bar"")
},
success: function(response) {
if (typeof response === 'string' && response.substring(0, 5) == ""ERROR"")
{
return response;
}
else
{
//pageReload();
return ""OK"";
}
},
error: function(xhr, textStatus, errorThrown) {
return errorThrown + ""\n"" + xhr.responseText;
},
complete: function() {
return ""COMPLETE"";
}
});
})();", null);
tasks.ContinueWith(t =>
{
if (!t.IsFaulted)
{
var response = t.Result;
if (response.Success)
{
if (response.Result != null)
{
MessageBox.Show(response.Result.ToString());
}
}
else
{
MessageBox.Show(response.Message, "Ein Fehler ist aufgetreten", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
}, TaskScheduler.Default);
Afterwards I have read that there is a SchemeHandler, but I do not properly understand how to implement it. Can anyone help me out?
Thanks in advance.

Firstly SchemeHandler is unlikely to be suitable in this scenario, you would typically implement a SchemeHandler when your providing the response.
Most people choose to bind an object, and call a method on their bound object when they wish to communicate with the parent application. See the FAQ for an example. https://github.com/cefsharp/CefSharp/wiki/Frequently-asked-questions#3-how-do-you-expose-a-net-class-to-javascript
With 49.0.0 you can implement ResponseFilter to gain access to the underlying response buffer, it's complex and not well documented, so if your not comfortable digging through reference C++ code then this option isn't for you. Here's a reference https://github.com/cefsharp/CefSharp/blob/cefsharp/49/CefSharp.Example/Filters/PassThruResponseFilter.cs#L17

Something that I did was create an element on the page through javascript with an ID that is the response of the ajax call. So for example, when you make an ajax call assign an ID to the ajax call.
When the ajax call returns, write an element on the page with the pre-assigned id and callback information. Then you can just use cefsharp to read the element content from the page and this will be your callback information.
var myDivElement =document.getElementById('textareaInfo');
if( myDivElement === null)
{
var input = document.createElement('textarea');
input.id = "textareaInfo";
input.value = "Test"
input.rows="4";
input.cols="50";
input.style="height:100%;width:900px;"
var dom = document.getElementsByClassName("page-body")[0];
dom.insertAdjacentElement('afterbegin', input)
}
Then later with ajax
var root = 'https://jsonplaceholder.typicode.com';
var _holder = callbackObj;
callbackObj.showMessage(""ajax"");
$.ajax({
url: root + '/posts/1',
contentType: 'application/json; charset=utf-8',
method: 'GET',
complete: function(data){
},
success: function(response) {
$(#'textareaInfo').value(response);
}
}).then(function(data) {
callbackObj.showMessage(data);
});
Then read the texarea from cefsharp in c#
chromeBrowser.GetMainFrame().EvaluateScriptAsync(function()...$(textareaInfo).value).Result

You can use PostMessage javascript method to notify .NET application:
CefSharp.PostMessage('Your data Here');
Here is .NET code example for headless browser:
var browser = new ChromiumWebBrowser("", null, RequestContext);
browser.JavascriptMessageReceived += (sender, e) =>
{
if ((string)e.Message.notificationid == "notification1")
{
// Your processing code goes here
}
};
browser.Load(destinationUrl);
browser.ExecuteScriptAsync("(function() { ... ; CefSharp.PostMessage({data: data, notificationid: 'notification1'});})()");

how to find which method is causing the error during parallel ajax call

I am using $.when to make parallel ajax call to webapi controller and it works perfectly fine. The structure is given below,
$.when(GetDataFromMethodA(),GetDataFromMethodB(),GetDataFromMethodC())
.done(function (responseFromMethodA,responseFromMethodB, responseFromMethodC) {
if (responseFromMethodA != null) {
//do some action
}
if (responseFromMethodB != null) {
//do some action
}
if (responseFromMethodC != null) {
//do some action
}
}).fail(function (xhr, textStatus, errorThrown) {
//which method raised the exception?
});
Methods:
function GetDataFromMethodA() {
var Request = {};
Request.Code = name.find(':selected').val();
return $.ajax({
url: 'api/Data/GetCurrentView',
type: 'POST',
dataType: 'json',
data: Request
});
}
similarly, I have method B and C.
QUESTION:
There are situations where any one of the method fails and based on the failing method, I need to display appropriate message to the user. When anyone of the method fails, the exception is caught in the 'fail' section. But, how to find which method raised the exception?

If you use always instead of done, you can inspect whether the request succeeded with isResolved() or isRejected(), for instance:
$.when(GetDataFromMethodA(),GetDataFromMethodB(),GetDataFromMethodC())
.always(function (responseFromMethodA,responseFromMethodB, responseFromMethodC) {
if(responseFromMethodA.isRejected()) {
console.log('A did not work!');
}
if(responseFromMethodB.isRejected()) {
console.log('B did not work!');
}
// ...etc.
});

Fetch data on different server with backbone.js

I can't see what the problem with this is.
I'm trying to fetch data on a different server, the url within the collection is correct but returns a 404 error. When trying to fetch the data the error function is triggered and no data is returned. The php script that returns the data works and gives me the output as expected. Can anyone see what's wrong with my code?
Thanks in advance :)
// function within view to fetch data
fetchData: function()
{
console.log('fetchData')
// Assign scope.
var $this = this;
// Set the colletion.
this.collection = new BookmarkCollection();
console.log(this.collection)
// Call server to get data.
this.collection.fetch(
{
cache: false,
success: function(collection, response)
{
console.log(collection)
// If there are no errors.
if (!collection.errors)
{
// Set JSON of collection to global variable.
app.userBookmarks = collection.toJSON();
// $this.loaded=true;
// Call function to render view.
$this.render();
}
// END if.
},
error: function(collection, response)
{
console.log('fetchData error')
console.log(collection)
console.log(response)
}
});
},
// end of function
Model and collection:
BookmarkModel = Backbone.Model.extend(
{
idAttribute: 'lineNavRef'
});
BookmarkCollection = Backbone.Collection.extend(
{
model: BookmarkModel,
//urlRoot: 'data/getBookmarks.php',
urlRoot: 'http://' + app.Domain + ':' + app.serverPort + '/data/getBookmarks.php?fromCrm=true',
url: function()
{
console.log(this.urlRoot)
return this.urlRoot;
},
parse: function (data, xhr)
{
console.log(data)
// Default error status.
this.errors = false;
if (data.responseCode < 1 || data.errorCode < 1)
{
this.errors = true;
}
return data;
}
});

You can make the requests using JSONP (read about here: http://en.wikipedia.org/wiki/JSONP).
To achive it using Backbone, simply do this:
var collection = new MyCollection();
collection.fetch({ dataType: 'jsonp' });
You backend must ready to do this. The server will receive a callback name generated by jQuery, passed on the query string. So the server must respond:
name_of_callback_fuction_generated({ YOUR DATA HERE });
Hope I've helped.

This is a cross domain request - no can do. Will need to use a local script and use curl to access the one on the other domain.

backbone sync callback always use error

I am having a hard time figuring out how to get the callback to work correctly when using Backbone sync. I am looking at my return packets and the response code is 200 which is no error, yet the alert("fail") statement gets called. I am requesting a response from a java servlet. Any idea guys? Thanks
Backbone.sync("read", this.model, {
url : "some url",
success: function(model, response) {
alert(response);
},
error: function(model, response) {
alert("fail");
}
});

I don't understand what you are doing...
Use this methods instead of sync:
model.fetch();
model.save();
model.destroy();
They will call sync, and they work perfectly.
I don't think it's necessary to override the original sync, it is good enough. I created a mock sync for an example application, this is how it works:
var User = Backbone.Model.extend({
notAllowedEmailHost: "gmail.com",
sync: function (method, model, options) {
if (method == "read" || method == "delete")
throw new Error("Example is not prepared for these methods.");
var email = model.get("email");
var status = 201;
if (email.indexOf(this.notAllowedEmailHost) != -1)
status = 400;
else if (method == "update")
status = 500;
options.xhr = {
status: status
};
if (status >= 400)
options.error(options.xhr);
else
options.success({
id: 1
});
}
});
The methods above create wrapper functions around your callbacks, and in sync those wrappers are called with the result. So the callback in sync is not the callback you give by the call of fetch, save or destroy functions...

Make sure that your servlet returns a JSON object, even if it's empty. This fixed the issue in my case.

Issues with handling http errors with jQuery AJAX webservice calls

I'm developing an jQuery application in where I've a requirement to capture HTTP errors as and when it occurs. Below is my snippet.
// Function to validate URL
function validateURL(url)
{
var pattern = new RegExp();
pattern.compile("^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$");
if (!pattern.test(url))
{
return false;
}
return true;
}
// Generic error handler for handling the webservice requests.
function initWebService(wstype, wsurl,jsonData)
{
// If the method parameter is not either "GET" or "POST" display an error message to the developer.
var msgValidateArgument;
var wsCallStatus;
var callbackData;
if ((arguments[0] != 'GET') && (arguments[0] != 'POST'))
{
//alert("Invalid");
//alert("You must provide a valid http method in your webservice call.");
msgValidateArgument = "You must provide a valid http method in your webservice call.";
return msgValidateArgument;
}
// Making sure whether the developer is passing the required number of parameters.
if(arguments.length < 3)
{
//alert("Some required arguments seems to be missing. Please check your webservice invocation.");
msgValidateArgument = "Some required arguments seems to be missing. Please check your webservice invocation.";
return msgValidateArgument;
}
if (!validateURL(arguments[1]))
{
msgValidateArgument = "You must provide a valid URL in your webservice call.";
return msgValidateArgument;
}
if(arguments[2] != ''){
var response=jQuery.parseJSON(arguments[2]);
if(typeof response =='object'){
//It is JSON
alert(response.toSource());
}
else{
msgValidateArgument = "The JSON data being passed is not in valid JSON format.";
return msgValidateArgument;
}
}
// Making the AJAX call with the parameters being passed. The error handler handles some of the possble http error codes as of now.
$.ajax({
type: arguments[0],
url: arguments[1],
data: arguments[2],
dataType: 'json',
async:false,
statusCode:{
404: function(){
alert('Page not found');
},
500: function(){
alert('Page not found');
},
504: function(){
alert('Unknown host');
}
},
success: function(data){
//alert('Data being returned from server: ' +data.toSource());
//alert('Data being returned from server: ' +data.toSource());
//alert(data);
callbackData = data;
}
});
return callbackData;
}
But, when I programatically change the webservice url to hold a wrong value, and upon calling the html page, I'm able to see an error message in the firebug console, but my snippet doesn't seem to be catching the error at all.
For e.g, While calling the GEONames API, I'm encountering an stating "407 Authorization required" in firebug's console.but even if I handle that status code in my error block, it is not firing.. What could be the reason?.
Don't we have any comprehensive solution for handling these HTTP errors effectively?.

I think there are a few problems with your code ... firstly how is handleError called ? because you call a method called handleError but pass nothing ... im assuming your using .ajax()
You should do it like this :
$.ajax({
statusCode: {
404: function() {
alert('page not found');
},
500: function() {
alert('server error');
}
},
success : {
alert('it working');
},
complete : {
alert('im complete');
});