I want to execute a callback function inside an object. I don't know if there is something wrong in the way I'm doing this.
I've googled for a solution, also searched on stackoverflow but couldn't find anything similar to the way I'm coding this.
PHPGateway.js
var PHPGateway = {
opt_friendlyURL: true,
opt_folder: 'ajax/',
callback_function: null,
useFriendlyURL: function (bool) {
this.opt_friendlyURL = bool;
},
setFolder: function (folder) {
this.opt_folder = folder;
},
send: function (service, method, data, callback) {
var url,
json_data = {};
if (this.opt_friendlyURL) {
url = this.opt_folder + service + '/' + method;
} else {
url = this.opt_folder + 'gateway.php?c=' + service + '&m=' + method;
}
if (data != undefined) {
json_data = JSON.stringify(data);
}
this.callback_function = (callback == undefined) ? null : callback;
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
success: this.ajax_success,
error: this.ajax_error
});
},
ajax_success: function (returned_object) {
if (this.callback_function != null) {
this.callback_function(returned_object.error, returned_object.data);
}
},
ajax_error: function () {
this.callback_function.call(false, {});
}
};
Then inside the HTML file that loads PHPGateway.js, I've the following code:
<script>
function submit_handler(event) {
event.preventDefault();
form_submit();
}
function form_callback(error, data) {
if(error == null) {
alert(data.text);
}
}
function form_submit() {
var data = {
status: $('#inStatus').val(),
amount: $('#inAmount').val(),
id: $('#inBudgetID'). val()
}
PHPGateway.send('budget', 'status', data, form_callback);
}
$('form').one('submit', submit_handler);
</script>
I get an error on this.callback_function(returned_object.error, returned_object.data);, the error is Uncaught TypeError: Object # has no method 'callback_function'.
What am I doing wrong?
Is this the best way to do it?
Thank You!
Based on minitech answer, I've updated PHPGateway.js like this. I've omitted the parts that weren't updated.
var PHPGateway = {
// Omitted code
send: function (service, method, data, callback) {
var url,
json_data = {},
that = this;
if (this.opt_friendlyURL) {
url = this.opt_folder + service + '/' + method;
} else {
url = this.opt_folder + 'gateway.php?c=' + service + '&m=' + method;
}
if (data != undefined) {
json_data = JSON.stringify(data);
}
this.callback_function = (callback == undefined) ? null : callback;
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
success: function(data, textStatus, jqXHR) {
that.ajax_success(data, textStatus, jqXHR);
},
error: function(jqXHR, textStatus, errorThrown) {
that.ajax_error(jqXHR, textStatus, errorThrown);
}
});
},
ajax_success: function (data, textStatus, jqXHR) {
if (this.callback_function != null) {
this.callback_function(true, data.data);
}
},
ajax_error: function (jqXHR, textStatus, errorThrown) {
this.callback_function.call(false, {});
}
};
Now it works!!!
In your call to $.ajax, you need to add a context option:
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
context: this,
success: this.ajax_success,
error: this.ajax_error
});
Your this variable in your Ajax success and error handlers are not pointing to the object you think they are. The context option to $.ajax() sets which object this points to in the Ajax callbacks.
Here’s your problem:
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
success: this.ajax_success,
error: this.ajax_error
});
When you set success and error to methods on this, they don’t keep their this. When a JavaScript function is called, it gets bound a this:
someFunction(); // this is undefined or the global object, depending on strict
someObject.someFunction(); // this is someObject
The built-in .call, .apply, and .bind of Function objects help you override this.
In your case, I think jQuery binds this to the Ajax object – a good reason to both not use jQuery and always use strict mode.
If you can guarantee or shim ES5 support, bind is an easy fix:
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
success: this.ajax_success.bind(this),
error: this.ajax_error.bind(this)
});
Which is equivalent to this if you can’t:
var that = this;
$.ajax({
method: 'POST',
url: url,
data: {data: json_data},
success: function() {
that.ajax_success.apply(that, arguments);
},
error: function() {
that.ajax_error.apply(that, arguments);
}
});
And now, a tip for you: don’t namespace, and if you do, don’t use this. this is great for objects that are meant to be constructed. What would seem more appropriate is something like this, if you really have to:
var PHPGateway = (function() {
var callbackFunction;
var options = {
friendlyURL: true,
…
};
…
function send(service, method, data, callback) {
…
}
…
return { send: send };
})();
Related
I'm trying to update an Observable from within an Ajax callback using...
function LocaleVM() {
const self = this;
self.Language = ko.observable("en");
self.Strings= ko.observable();
self.toggleLanguage = function () {
const lang = self.Language() === 'en' ? 'es' : 'en';
console.log(self.Language());
console.log(lang);
$.ajax({
url: `/${lang}`,
method: 'GET',
success: function (data, textStatus, xhr) {
self.Language(lang);
console.log(self.Language());
console.log(lang);
//===============================================
... update strings ...
},
error: function (xhr, textStatus, errorThrown) {
console.log(errorThrown);
}
});
}
}
And that is the console output every time toggleLanguage gets called...
en
es
es
es
Which seems to be updating fine within the call back but not outside. What seems to be the problem here?
It looks like you're never actually updating the value of the Language observable.
Here is a condensed version of your script...
self.toggleLanguage = function () {
const lang = self.Language() === 'en' ? 'es' : 'en';
$.ajax({
url: `/${lang}`,
method: 'GET',
success: function (data, textStatus, xhr) {
self.Language(lang); // <<< THIS IS ALWAYS THE SAME VALUE.
console.log(self.Language());
console.log(lang);
}
});
}
I can only assume the values you're fetching in that AJAX request but don't you want something like this?
self.toggleLanguage = function () {
$.ajax({
url: `/${lang}`,
method: 'GET',
success: function (data, textStatus, xhr) {
self.Language(data); // <<< USE THE NEWLY-FETCHED VALUE.
console.log("Previous value: " + lang);
console.log("Current value: " + self.Language());
}
});
}
Below is my code and issue is with cache code is not working properly if any ajax call has callback in success.
var localCache = {
/**
* timeout for cache in millis
* #type {number}
*/
timeout: 30000,
/**
* #type {{_: number, data: {}}}
**/
data: {},
remove: function (url) {
delete localCache.data[url];
},
exist: function (url) {
return !!localCache.data[url] && ((new Date().getTime() - localCache.data[url]._) < localCache.timeout);
},
get: function (url) {
console.log('Getting in cache for url' + url);
return localCache.data[url].data;
},
set: function (url, cachedData, callback) {
localCache.remove(url);
localCache.data[url] = {
_: new Date().getTime(),
data: cachedData
};
if ($.isFunction(callback)) callback(cachedData);
}
};
$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
if (options.cache) {
var complete = originalOptions.complete || $.noop,
url = originalOptions.url;
//remove jQuery cache as we have our own localCache
options.cache = false;
options.beforeSend = function () {
if (localCache.exist(url)) {
complete(localCache.get(url));
return false;
}
return true;
};
options.complete = function (data, textStatus) {
localCache.set(url, data, complete);
};
}
});
function handleAjaxRequests(url, parameters, headers, method, successHandler, options, errorHandler) {
if (typeof (method) === 'undefined') {
method = "GET";
}
if (typeof (headers) === 'undefined') {
headers = "";
}
if (typeof (parameters) === 'undefined') {
parameters = "";
}
successHandler = typeof (successHandler) === 'undefined' ? function (data) {} : successHandler;
errorHandler = typeof (errorHandler) === 'undefined' ? function (data) {} : errorHandler;
return $.ajax({
method: method.toUpperCase(),
url: url,
// async: false,
data: parameters,
headers: headers,
success: function (data) {
console.log('hi');
successHandler(data, options);
console.log('bye');
},
error: function (data) {
$('.loader').hide();
errorHandler(data);
},
});
}
As per the above code after successfully run ajax successHandler(data, options);function should be the trigger but it not due to above cache handler code. I have no idea why this is not working. If I write simple something rather than callback function it is working. Same issue with datatable Ajax callbacks.
I have to use above cache handler at global level in my project doesn't matter ajax request is from datatable or from any other source.
Above cache code is from here https://stackoverflow.com/a/17104536/2733203
As discussed in the chatroom I've made some changes in your code :
var localCache = {
/**
* timeout for cache in millis
* #type {number}
*/
timeout: 30000,
/**
* #type {{_: number, data: {}}}
**/
data: {},
remove: function(url) {
delete localCache.data[url];
},
exist: function(url) {
return !!localCache.data[url] && ((new Date().getTime() - localCache.data[url]._) < localCache.timeout);
},
get: function(url) {
console.log('Getting in cache for url ' + url);
return localCache.data[url].data;
},
set: function(url, cachedData, callback) {
localCache.remove(url);
localCache.data[url] = {
_: new Date().getTime(),
data: cachedData
};
console.debug('caching data for '+url, cachedData);
if ($.isFunction(callback)) callback(cachedData);
}
};
$.ajaxPrefilter(function(options, originalOptions, jqXHR) {
if (options.cache) {
var complete = originalOptions.complete || $.noop,
url = originalOptions.url;
//remove jQuery cache as we have our own localCache
options.cache = false;
options.beforeSend = function() {
if (localCache.exist(url)) {
console.log('using cache, NO QUERY');
complete(localCache.get(url));
return false;
}
console.log('sending query');
return true;
};
options.complete = function(data, textStatus) {
localCache.set(url, data, complete);
};
}
});
function handleAjaxRequests(url, parameters, headers, method, successHandler, options, errorHandler) {
method = method || "GET";
headers = headers || {};
parameters = parameters || {};
return $.ajax({
method: method.toUpperCase(),
url: url,
cache: true,
// async: false,
data: parameters,
headers: headers,
success: successHandler,
error: errorHandler,
});
}
handleAjaxRequests('/echo/json/', {p1: 'hey'}, null, 'POST', function(data){console.log('first success without cache', data);});
setTimeout(function(){
handleAjaxRequests('/echo/json/', {p1: 'hey'}, null, 'POST', function(data){console.log('success! with cache hopefully', data);});
}, 2000);
Fiddle here
added some logs in the localCache methods to see what's happening. Cache is never used so I've added the missing cache:true option
Added some logs inside beforeSend method to monitor the toggle between cache and query. Everything works fine.
Cleaned up the arguments null checks and removed empty function(){} (use $.noop() instead btw.
Now the core of your issue. The callbacks errorHandler and successHandler are arguments. $.ajax is asynchronous! it means at some point of the execution, right after this call is made, you won't be sure if the variable has the same value. Easiest solution is to just reference the function directly and let jQuery do the scope management. Hardest solution would be to give these functions to the context option in ajax settings which I don't recommend.
Now, the solution you use allows you to directly call $.ajax without a wrapper method. Why don't you use it directly? simpler and less prone to errors
EDIT: I'm really not fond of context so there is another alternative.
function handleAjaxRequests(url, parameters, headers, method, successHandler, options, errorHandler) {
method = method || "GET";
headers = headers || {};
parameters = parameters || {};
return $.ajax({
method: method.toUpperCase(),
url: url,
cache: true,
// async: false,
data: parameters,
headers: headers,
success: (function(handler, opt) {
return function( /*Anything*/ data, /*String*/ textStatus, /*jqXHR*/ jqXHR) {
console.log('hi');
handler(data, opt);
console.log('bye');
};
})(successHandler, options),
error: (function(handler, opt) {
return function( /*jqXHR*/ jqXHR, /*String*/ textStatus, /*String*/ errorThrown) {
console.log('ouch');
handler(errorThrown);
};
})(errorHandler, options),
});
}
You scope the function with this well known javascript trick aka currying.
New fiddle here.
EDIT 2: if you want successHandler to run even when getting from cache you should use complete instead of success
function handleAjaxRequests(url, parameters, headers, method, successHandler, options, errorHandler) {
method = method || "GET";
headers = headers || {};
parameters = parameters || {};
return $.ajax({
method: method.toUpperCase(),
url: url,
cache: true,
// async: false,
data: parameters,
headers: headers,
complete: (function(handler, opt) {
return function( /*Anything*/ data, /*String*/ textStatus, /*jqXHR*/ jqXHR) {
console.log('hi');
handler(data, opt);
console.log('bye');
};
})(successHandler, options),
error: (function(handler, opt) {
return function( /*jqXHR*/ jqXHR, /*String*/ textStatus, /*String*/ errorThrown) {
console.log('ouch');
handler(errorThrown);
};
})(errorHandler, options),
});
}
Fiddle here.
I have a function in JS & jQuery that fires an AJAX call and it has a callback block to let me know when it's finished:
function ajaxCall(url, type, dataType, dataToSend, callback) {
if (dataType == undefined) dataType = "json";
if (dataToSend == undefined) dataToSend = null;
$.ajax({
url: url,
type: type,
dataType: dataType,
contentType: "application/json",
data: dataToSend,
async: true,
success: function (result) {
callback(result);
},
error: function (data, status) {
console.error("Server Error: " + status);
}
});
}
I am accessing it like so, but using external functions like showAjaxLoader() just doesn't work! it says this function is undefined:
function registerUser(data) {
ajaxCall(pathServiceRegister, "POST", undefined, JSON.stringify(data), function (result) {
// SOME CODE THAT RUNS WHEN IT'S COMPLETE
// External method:
showAjaxLoader(false); // Doesn't work
});
});
function showAjaxLoader(show) {
var loader = $('.ajax-loader');
if (show) {
loader.fadeIn("fast");
} else {
loader.fadeOut("fast");
}
}
What am I doing wrong?
Thanks :)
Worked out some sample. this may be good practice. Try this :
$(document).ready(function() {
$("button").click(function() {registerUser();});
});
var Scallback = function(arg) {
alert("Success :"+arg);
showAjaxLoader(true);
}
var Ecallback = function(arg) {
alert("Err :"+arg);
showAjaxLoader(true);
}
function showAjaxLoader(show) {
var loader = $('.ajax-loader');
if (show) {
loader.fadeIn("fast");
} else {
loader.fadeOut("fast");
}
}
function ajaxCall(url, type, Scallback, Ecallback) {
$.ajax({
url : url,
type : type,
async : true,
success : function(result) {
Scallback(result);
},
error : function(data) {
Ecallback(data)
}
});
}
function registerUser()
{
ajaxCall(pathServiceRegister, "GET", Scallback, Ecallback);
}
Have you tried to do something like:
var that = this;
function registerUser(data) {
ajaxCall(pathServiceRegister, "POST", undefined, JSON.stringify(data), function (result) {
// SOME CODE THAT RUNS WHEN IT'S COMPLETE
// External method:
that.showAjaxLoader(false);
});
});
Declare your method like this
var obj = {
showAjaxLoader : function(show) {
var loader = $('.ajax-loader');
if (show) {
loader.fadeIn("fast");
} else {
loader.fadeOut("fast");
}
}
}
Then inside ajax, call obj.showAjaxLoader(false); This may work.
How to call pagePresets.setFilter() inside $.ajax(){success} method?
self.setFilter.call('network', data.networks); returns
Uncaught TypeError: Cannot read property 'call' of undefined(…)
when self.setFilter('network', data.networks);
Uncaught TypeError: self.setFilter is not a function(…)
Code:
function pagePresets() {
this.loading = true;
this.isLoading = function () {
return this.loading;
};
this.setLoading = function (state) {
this.loading = state;
return;
};
/** this function loads saved filters */
this._loadFilters = function() {
jQuery.ajax({
type: 'post',
dataType: "json",
url: 'data.json',
success: function (data) {
//HOW TO CALL setFilter? this solution is not working
pagePresets.prototype.setFilter.call('network', data.networks);
}
});
};
}
pagePresets.prototype.setFilter = function (target, value) {
console.info(target + ' ' + value );
}
The call function takes as first argument a "context object". Take a deeper look at the call function here.
In the ajax callback function this or self doesn't refere to your class object anymore. And pagePresets is a function class with no static properties. So you need to get the object instance.
You need to specify which instance you want to call your prototype function with. I usualy declare a private property in my "class" wich holds a reference to the object for such scenarios where the context changes.
function pagePresets() {
//create a local variable here
var localInstance = this;
this.loading = true;
this.isLoading = function () {
return this.loading;
};
this.setLoading = function (state) {
this.loading = state;
return;
};
/** this function loads saved filters */
this._loadFilters = function() {
jQuery.ajax({
type: 'post',
dataType: "json",
url: 'data.json',
success: function (data) {
//Use the variable here to specify the correct context.
//the functions arguments need to be an array for the call function
pagePresets.setFilter.call(localInstance, [ 'network', data.networks ]);
}
});
};
}
pagePresets.prototype.setFilter = function (target, value) {
console.info(target + ' ' + value );
}
you can try to invoke that in the another function like this
function success() {
pagePresets.prototype.setFilter.call('network', data.networks);
}
function error() {
alert("error");
}
function searchEntity(id,userName, family) {
$.ajax({
type : "POST",
contentType : "application/json",
url : "http://localhost:8080/mvc-test/rest/user/searchAll?pageNumber=1&pageSize=2&&orderBy=userName asc",
headers: {'X-CSRF-TOKEN': getMetaContentByName('_csrf')},
data : JSON.stringify({
"id":id,
"userName" : userName,
"familyName" : family
}),
dataType : 'json',
success : success,
error : error
});
}
Another way is to pass the parent context into the success method or delegate.
In the code below, onAjaxResponseReceived function is called with with the reference to the parent (class) context self from which other methods func1 and func2 can be accessed.
class TestClass{
constructor(searchUrl) {
this.searchUrl = searchUrl;
}
bind() {
self = this;
$.ajax({
url: self.searchUrl,
type:"POST",
data: data,
success: function (responseData) {
self.onAjaxResponseReceived(self, responseData);
}
});
}
onAjaxResponseReceived(self, data) {
self.func1(data);
self.func2(data);
}
func1(data) {
console.log('func 1');
}
func2(data) {
console.log('func 2');
}
}
I have over 50 AJAX calls from different functions of my code. All these calls have a similar structure with different data/url/callback params:
var jqXHR = $.post('/dba/port.php', {
mode: "del_wallfunds",
pdata: cdata,
wname: wName
},
function (data) {}, "json")
.done(function (data) {
var msg = data.msg;
if (msg.indexOf("Error") == -1) {
alertify.success(msg);
delSelected(selGroup);
} else {
alertify.error(msg);
}
})
.fail(function () {
alertify.error("Error .....");
});
I am thinking how to write a function that would return that var jqXHR to minimize the total size of the code. It is not a problem to pass all static variables like URL, error strings etc. But the problem is that all callback functions on ".done" are different and I don't know how to pass these callback functions as variables.
One way would be to call a single "universal" function on .done and pass a "switch" variable to that function, but it doesn't seem to be an elegant solution.
Any suggestions how to it in some elegant way?
Thanks
Either pass the done callback function as an argument when calling your function:
function ajaxCall(url, data, doneCallback) {
return $.post(url, data, doneCallback, "json").fail(...);
// or
return $.post(url, data, function() {}, "json").done(doneCallback).fail(...);
}
var jqXhr = ajaxCall('yoururl.php', {key: 'value'}, function(data) {
// do something
});
Or return the jqXhr object from the function, and assign the done callback then:
function ajaxCall(url, data) {
return $.post(url, data, function() {}, "json").fail(...);
}
var jqXhr = ajaxCall('yoururl.php', {key: 'value'});
jqXhr.done(function(data) {
// do something
});
Alternatively switch to using jQuery.ajax() instead, and pass the entire options object in:
function ajaxCall(options) {
return $.ajax(options).fail(...);
}
var jqXhr = ajaxCall({
url: 'yoururl.php',
data: {key: 'value'},
dataType: 'json'
});
jqXhr.done(function(data) {
// do something
});
You can try to :
turn "request successfully returned a treatment error" into a "rejected request",
put the "alertify" processing in a common callback
Here is a sketch of what this could give :
function myAjaxApi(url, data){
var myAjaxCall = $.post(url, data, function (data) {}, "json")
.then(function (data) {
// using .then : change "request succesful with error state"
// to "rejected state"
var msg = data.msg;
if (msg !== undefined && msg.indexOf("Error") >= 0) {
var dfd = $.Deferred();
// try to match the same signature as the "error" option
dfd.reject(this, msg);
return dfd;
} else {
return data
}
});
myAjaxCall.done(function(data){
if (data.msg) {
alertify.success(data.msg);
}
}).fail(function (jqxhr, msg) {
if (!msg) { msg = "Error ....."; }
alertify.error(msg);
});
return myAjaxCall;
}
//usage
myAjaxApi('/dba/port.php', {mode: "del_wallfunds", pdata: cdata, wname: wName})
.done(function (data) {
// the ".done()" queue will not be executed if msg contains "Error" ...
delSelected(selGroup);
});
Some parts should be written with more care ; the above example is meant to illustrate how you can wrap your repeated ajax calls inside a common api.