getting json string from web service - javascript

I have got a web service which gets list of users from an external system and returns as json. and I call that webservice via jquery ajax.; I have placed ajax code below
$.ajax({
type: "GET",
url: webMethod,
data:"",
contentType: "application/json; charset=utf-8",
dataType: "jsonp",
success: function(msg) {
alert(msg.d);
},
error: function(e) {
alert(e);
}
});
Even though, the output is in correct format, the output I get from jquery.ajax seems to be wrong. it returns big chunk of the data correctly, then adds "; (" and continues to show the output.
Basically, the output is ("around %75 of data");(rest of the data) which makes my json invalid. I am not sure whether it is related to the maxJasonLenght or not but I also set it to the maximum. there seems to be a limitation on how much data you can get from web service as if I add more data to that json, the break down point changes.
Sample Output
[{"UserName":"a.b","FullName":"a b"},{ Many other users},{"UserName":"c.d","FullName":"c d"},{"UserName":"e.f",);jsonp1364397526212("FullName":"e f"}, {"UserName":"g.h","FullName":"g f"},{other users}}
do you have any idea why I am having this issue?
Thanks

Do you set the crossDomain option to TRUE? If I'm not wrong, if you set the crossDomain option to TRUE, the response would be JSON-P.
Look at this post so you can figure out how to handle the response:
What is JSONP all about?
I hope it would help!

Related

Ajax data sending format

Is my Ajax format something wrong?
I am trying to send a simple digit 1/0 data to a tomcat server, using ajax
but getting no response. The whole view is at a standstill.
$.ajax({
type: "GET",
cache: false,
async: false,
url: "http://192.168.200.163:8080/ControllerWebServer/mainCTRL.jsp",
data: “fan=” + fan,
success: function(fan){
alert(fan);
},
error: function(){
alert("Ajax Error.");
}
});
If I make this ajax block as a comment, other functions (which is not displayed here) work just well. I tried GET AND POST, and just the same: don't work.
please help... :(
Try changing this
data: “fan=” + fan,
to
data: {fan: fan},
This is how data should be formatted.
sorry i have low reputation so i couldnt make comment.
when you using data: {fan: fan}, you need to specify the dataType:'json' in your ajax

Long polling with ajax and servlets

I'm doing a project using javascript for client side and servlets for server side. I'm trying to implement a way to update client info real time. i.e when a client update some info in the web application, other clients will also see the update. I found that long polling is a good technique for this. This is the code I tried to get to work.
function poll() {
setTimeout(function() {
$.ajax({
type: "GET",
url: "server",
contentType: "application/json",
data: {
type: "update",
card: "string"
},
success: function(data) {
alert(data);
},
error: function(data) {
alert('eroor');
},
dataType: "json",
complete: poll });
}, 5000);
}
I'm trying to send a request to the server every 5 seconds and get the response with new updates. But in all the skeleton codes I saw in the web, data: is not set. Without setting it, how would the sever know the type of request it received since there are other types of requests too. But when I set data: no requests are sent from the client. But without setting data: requests are sent to the server. Is it wrong to set data: ? Without it how would I let the servlet know the type of the request?
I understand that like mentioned in here long polling is not what I'm trying to do. But can anyone explain what I should do and where I'm doing wrong.
Since you make a GET request, the data values are appended to the URL as URL parameters. Your servlet must then use request.getParameter("type") and request.getParameter("card") to extract the information from the request.
If you think that no request is sent, first check your console for errors and look at the net communications panel in the developer tools of your browser.
data:
issue is how you set the data. If you want to send json object, you have to stringify before you send it, like below.
$.ajax({
url: url,
type: "POST",
data: JSON.stringify(data),
contentType: "application/json",
complete: callback
});
Without it how would I let the servlet know the type of the request?
What you mean by this? to know the contentType? If so, send contentType parameter as above.
I understand that like mentioned in here long polling is not what I'm trying to do. But can anyone explain what I should do and where I'm doing wrong.
Yes. This is not exactly a long polling. This is how you send a request to the server in every 5 seconds. Anyway server should support to long polling.

Retrieve value from open external API - visual studio - javascript - AJAX

I would really appreciate some advice, I'm trying to retrieve information from an open API for the first time.
The API details are here,
https://data.police.uk/docs/method/neighbourhood-locate/
I want to retrieve the 'force' and 'neighbourhood' values and save them into variables, I want to save them as variables as I'm then calling googlemaps to display the KML map. I managed to get quite far on other sections of my code, such as geocoding a user inputted address and retrieving the Long/Lat, but I am now struggling to send the long/lat to the external API and save the response.
I've hardcoded the long/lat into the below URL for this advice request, I think I'm getting a response from the API but failing to capture the values into my variables. The debugger shows the following response, {"force":"metropolitan","neighbourhood":"00BK17N"}, below is my code,
var ForceId; //returned from the API
var Neighbourhood; //returned from the API
accessURL = "https://data.police.uk/api/locate-neighbourhood?q=51.500617,-0.124629"
//Use the zip code and return all market ids in area.
$.ajax({
type: "GET",
contentType: "application/json; charset=utf-8",
url: accessURL,
dataType: 'jsonp',
success: function (data) {
ForceId.push(val.force);
Neighbourhood.push(val.Neighbourhood)
console.log(ForceId);
console.log(Neighbourhood);
}})
I made a few mistakes, after seeing the responses were coming back as errors for its syntax, I adjusted some settings, I removed contenttype as 'application/JSON' and the response could be seen in the consolelog to contain the needed parameters. I'm not sure of the implications of doing this or if its bad practice as I'm extremely new at this, its my first attempt at working with API's. So other may advise better.
function GetPolice(){
$.ajax({
type: "GET",
// contentType: "application/json; charset=utf-8",
url: accessURL,
dataType: 'json',
success: function(data) {
ForceId = data.force;
Neighbourhood = data.neighbourhood;
},
})
}
If your new at this, then my suggestion is to tinker with 'success, error, complete' to see what responses are being returned to consolelog. Have a look at what your 'datatype' should be from the external API. Again, i'm not best placed to give advice but hope other new people find this helpful.
I now need to make the above a callback response, as it completes the function before the responsehas been recieved, I wish to use the response in another fucntion elsewhere, but thats a different challenge :)

Content-Type Ajax json missing

I wrote some php code that outputs some valid json, and sets the content-type header to application/json in my dev setup. However when I deploy this script to a embedded webserver it works fine except it's not capable of sending the content-type. It's not possible to run a other webserver.
Now I have the following code for Dynatable. Even though my dev and my embedded webserver, serve exactly the same file, and the only difference is the content-type. It works for my dev setup, however it doesn't work for my embedded setup.
I use the following code to load the json file to dynatable.
document.ready(
$.ajax({
url: 'phpApi.php',
success: function(data){
$('#myTable').dynatable({
dataset: {
records: data
}
});
}
}));
So can someone explain me why the content-type is so important for ajax? How can I tell my code manually its json?
Without the content-type the returned data is assumed to be plain text. There is nothing in your code to tell it otherwise.
One way to get json would be to specify the return type in the jquery code. Just add dataType: 'json' into the ajax configuration.
Or you could use eval() to transform the returned text to json.
document.ready(
$.ajax({
url: 'phpApi.php',
success: function(data){
$('#myTable').dynatable({
dataset: {
records: eval(data)
}
});
}
}));
Using JSON.stringify(eval(data)) might give you better results by making sure its json.
As pointed out below, JSON.parse(data) would probably be safer. (Eval is evil after all.)
So can someone explain me why the content-type is so important for ajax?
It's important so the client can identify what type of content the server returned, content-type: application/json tells jQUery to parse the data as an object. If no content type is returned, the client will assume the returned data is just plain text.
How can I tell my code manually its json?
Add dataType: "json" parameter to $.ajax()
document.ready(
$.ajax({
url: 'phpApi.php',
dataType: "json",
success: function(data){
$('#myTable').dynatable({
dataset: {
records: data
}
});
}
}));

jQuery $.ajax done callback not firing

I have the following code :
$("#loginSubmitButton").on("click",function(){
var loginUserDetails = {
email: $("#email").val(),
password: $("#password").val()
};
//Send the AJAX request to authenticate the user
$.ajax({
type: "POST",
url: "/somewebservice/v1/users/authenticate",
data: JSON.stringify(loginUserDetails),
contentType: "application/json;charset=UTF-8",
dataType: "json",
}).done(function() {
$("#loginResult").text("Login successful");
})
.fail(function() {
$("#loginResult").text("Login failed");
});
});
As per the jquery documentation (unless I am understanding something incorrectly) I expect the done to be fired if I receive a 200 OK from my web server. However, in chrome console I can see a 200 OK response but jquery seems to fire the fail handler.
Does anyone have any idea what I might be doing wrong here?
You need to remove:
dataType: "json"
There are lots of suggestions to remove
dataType: "json"
While I grant that this works it's probably ignoring the underlying issue. It's most likely caused by a parser error (the browser parsing the json response). Firstly examine the XHR parameter in either .always() or .fail().
Assuming it is a parser fail then why? Perhaps the return string isn't JSON. Or it could be errant whitespace at the start of the response. Consider having a look at it in fiddler. Mine looked like this:
Connection: Keep-Alive
Content-Type: application/json; charset=utf-8
{"type":"scan","data":{"image":".\/output\/ou...
In my case this was a problem with PHP spewing out unwanted characters (in this case UTF file BOMs). Once I removed these it fixed the problem while also keeping
dataType: json
If your server returns empty string for a json response (even if with a 200 OK), jQuery treats it as failed. Since v1.9, an empty string is considered invalid json.
Whatever is the cause, a good place to look at is the 'data' parameter passed to the callbacks:
$.ajax( .. ).always(function(data) {
console.log(JSON.stringify(data));
});
Its contents will give you an understanding of what's wrong.
Need to remove , from dataType: "json",
dataType: "json"
The ajax URL must be the same domain. You can't use AJAX to access cross-domain scripts. This is because of the Same Origin Policy.
add "dataType:JSONP" to achieve cross domain communication
use below code
$.ajax({
URL: cross domain
dataType: 'jsonp'
// must use dataType:JSONP to achieve cross domain communication, otherwise done function would not called.
// jquery ajax will return "statustext error" at }).always(function(data){}
}).always(function(data){
alert(JSON.stringify(data));
}
A few things that should clear up your issue and a couple hints in general.
Don't listen for a click on a submit button. You should wait for the submit event on the form.
The data option for $.ajax isn't expecting a JSON string. It wants a serialized string or an array with name and value objects. You can create either of those easily with .serialize() or .serializeArray().
Here is what I was thinking for your script.
$('#form-with-loginSubmitButton').on('submit', function(e){
e.preventDefault():
var $form = $(this),
data = $form.serializeArray();
$.ajax({
type: "POST",
url: "/somewebservice/v1/users/authenticate",
data: data
}).done(function(result){
console.log(result);
});
});

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