Is there a way to call a Page Method in jQuery when the page method has a "params" argument type (in C#)?
I can call Page Methods all day long using jQuery if I specify the arguments one at a time, but if I put them as "params object[] args" it throws an error about not finding the "args" parameter.
I am trying to call a method with the following signature:
public static string MakeWebServiceCall(string methodName, params string[] args)
But it only works if I specify it explicitly like this:
public static string MakeWebServiceCall(string methodName, string place, string type, string token)
Just double-check your JavaScript. It's more likely the culprit than a problem with your C#, as the significance of the params reserved word is non-existant. The argument is still ultimately an array of strings, which is nothing special to JSON. I've just built a quick test page which resulted in absolutely no problems using your method. Try double-checking your syntax against the following:
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "MyPage.aspx/MakeWebServiceCall",
data: '{"methodName":"myMethod", "args":["my","array","of","strings"]}',
dataType: "json"
});
OR if you'd like, stringify a data object using a JavasScript JSON library (native with newer browsers). This method is my personal favorite since I won't have to double-check that I've built my JSON string correctly. Just be sure to enable legacy support for IE7 if you're feeling kind:
var data = {};
data.methodName = "myMethod";
data.args = ["my","array","of","strings"];
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "MyPage.aspx/MakeWebServiceCall",
data: JSON.stringify(data),
dataType: "json"
});
If you're having difficulty with some of the particulars of how these arguments are constructed, you might check out this great resource article from Encosia that I go back to frequently just to remind myself of the basics of consuming web services and page methods with jQuery. It explains a couple of the oddities, including links back to pages which talk about why the contentType encoding is important, as well as information as to why the full JSON string must be provided to the data argument rather than just a JavaScript object.
Related
I have a C# .NET MVC 5 project. I'm trying to submit a GET request from ajax to a controller method on the server. The problem is that, even though this jquery is being called, the GET always returns a 404. Here is the js:
var theArguments = { "prefix": prefix, "level": level, "number": number };
$.ajax({
url: "GetMasteryObjective",
type: "GET",
data: theArguments,
//data: JSON.stringify({ prefix: "prefix", level: "level", number: "number" }),
//url: "/MasteryObjectiveAPI/GetMasteryObjective?prefix=" + prefix + "&level=" + level + "&number=" + number,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function () {
console.log("Successfully queried the database to validate the given mastery objective.");
},
error: function () {
console.log("There was an error with trying to validate the mastery objective with the database.");
}
});
As you can see I've tried several variants of how the variables are submitted (commented out). This is the controller method that is never getting hit.
[HttpGet]
//[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public static MasteryObjective GetMasteryObjective(String prefix, String level, String number)
{
//code here
}
Other methods in the same controller have no problem being posted to. So maybe there's something I don't understand about GET? I understand that it should be valid to submit variables with a GET request.
Wow. I just discovered the answer to my own question while creating this post. I needed to remove static from my controller method.
Happy that, you have got the solution.
However, thinking that this may help others .....
One of the reason for ajax call not hitting the Method in controller is:
If the controller method is under [Authorize] but the user is trying to hit without logging in.
Solution: If want to allow unauthorized access to that method; mark that method has [AllowAnonymous], otherwise log-in and then try.
In researching this problem most SO issues were about the static method as a fix.
Since it's not working with the real (and a bit sophisticated) WebMethod I've just created a simple one for the sake of checking if reaching the method itself is possible.
[WebMethod]
[ScriptMethod(UseHttpGet = false)]
public static string HelloWorld()
{
return "Hello World!";
}
The call.
<script>
$(document).ready(function () {
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "usersWebMethods.aspx/HelloWorld",
dataType: "json",
success: function (data) {
alert(data.d);
}
});
});
</script>
It always comes down to 500 (Internal Server Error)
Unknown web method HelloWorld.
Parameter name: methodName
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentException: Unknown web method HelloWorld.
Parameter name: methodName
Why is this failing?
I had this issue as well, but slightly differently I had this method in a .asmx file and so ran across the "static" issue, but in a different way.
If you have a method as part of your Page class, it must be static.
If you've put a method in an .asmx file to use across several pages, it must not be static.
I had a problem in the actual .aspx file, the line
<%# Page Language="C#"
AutoEventWireup="true"
CodeBehind="xxx.xxx.cs" Inherits="xxx.xxx" %>
wasn't present in the code. How did it get changed? I Don't know :(.
For me, the primary issues was to change javascript post to pass in no arguments such as
$http.post("Status.aspx/MyData", {})
Then to verify nothing was cached, I then deleted [System.Web.Services.WebMethod] in the code behind file above public static string MyData(). Then I built the project to failure, then re-added the aformentioned deleted attribute and built to success.
Upon running it worked.
Missing the [WebMethod] above your server side function will also cause this error.
To be honest, I've just realised "again" how tired we could be in some cases.
For me it was just a private method instead of a public one.
In my case there was a problem in the URL, it was a Asp.Net Website application:
For ex:
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "usersWebMethods.aspx/HelloWorld", <----- Here
dataType: "json",
success: function (data) {
alert(data.d);
}
});
My usersWebMethods.aspx in inside UI (Custom Created) folder so If I put URL as usersWebMethods.aspx/HelloWorld it does not work but when I added leading / to it then ajax method called properly!
Changed from:
usersWebMethods.aspx/HelloWorld
To
/usersWebMethods.aspx/HelloWorld --
I run into this exact problem in ASP.net(framework/web forms) with JS using webservice and I solved it by removing the static key word from the method declaration
[WebMethod]
public List<ViewModel> GetAirLines()
{
//Code goes here
}
instead of
[WebMethod]
public static List<ViewModel> GetAirLines()
{
//Code goes here
}
I have an asp.net application with a static page method. I'm using the below codes to call the method and get its returned value.
$.ajax({
type: "POST",
url: "myPage/myMethod",
data: "{'parameter':'paramValue'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(result) {alert(result);}
});
What i got returned is [object Object].
Below is my static method. And I also have EnablePageMethods="true" EnablePartialRendering="true" in my ScriptManager.
[WebMethod]
[ScriptMethod]
public static string myMethod(string parameter)
{
return "Result";
}
Is there a way for me to get the returned value?
Try using Chrome developer tools or the firebug plugin from Firfox. Not sure if IE's developer tools lets you inspect the ajax calls?
The resulting string you are looking for is actually within the result object. You need to look at the d variable. I remember reading somewhere why this was, I think it is ASP.NET playing around :|
Try:
success: function(data) {alert(data.d);}
c#
[WebMethod]
public static string GetTest(string var1)
{
return "Result";
}
Hope this helps.
Its just that you are stuck at the .d that is introduced in the JSON response from ASP.NET 3.5. To quote Dave Ward,
If you aren’t familiar with the “.d”
I’m referring to, it is simply a
security feature that Microsoft added
in ASP.NET 3.5’s version of ASP.NET
AJAX. By encapsulating the JSON
response within a parent object, the
framework helps protect against a
particularly nasty XSS vulnerability.
So just check whether .d exists and then unwrap it. Change your success function like this.
success: function(result) {
var msg = result.hasOwnProperty("d") ? result.d : result;
alert(msg );
}
What about this?
$.ajax({
type: "POST",
url: "myPage/myMethod?paramater=parameter",
success: function(result) {
alert(result);
}
});
I found out the solution.
You can use parseJSON to get the result
http://api.jquery.com/jQuery.parseJSON/
or change the datatype to html to see the actual value.
http://docs.jquery.com/Specifying_the_Data_Type_for_AJAX_Requests
Thank you guys for your help.
[NOTE:I am really looking for some good debugging techniques here. Perhaps some tricks or ways to simplify things of which I am unaware.]
I am using the technique of calling [WebMethods] defined in an ASPX page from JQuery as mentioned here and here. It seems to be an increasingly common method.
I've been using it for a while and, in general, it works great. But while developing it is pretty fragile. Any incorrect parameter will result in a really vague, non-specific, error message. For instance, if I have a fairly complex web method defined as:
[WebMethod]
public static string SaveComplexRecord(int recID, GeneralData general, SomeObject data, SomeOtherObject moreData)
{
//do a bunch of stuff with that data
}
And GeneralData, SomeObject, and SomeOtherObject all have a mix of various types of parameters (strings, ints, bools, datetimes.) It is very likely, especially during initial development, that I will build the JSON on the client side incorrectly. Perhaps I will do this:
var data = {
recID: curID,
general:
{
a: aValue,
b: bValue,
c: cValue
},
data:
{
d: dValue,
e: eValue,
f: fValue
},
moredata:
{
g: gValue,
h: hValue,
i: iValue
}
};
Which will result in an error because the name of the third parameter is moreData, not moredata. And that's just an example, there could be any of a hundred other subtle typo-style errors.
If I were calling this method from C# the compiler would give me an error message something like "No overloaded method of SaveComplexRecord takes three parameters." or some other helpful message that points you in the right direction.
So... is there a way of getting ASP.Net to produce better error messages here?
Or is there some utility that will automatically build the JSON parameter structure of a [WebMethod] call? (just like you can automatically get the WSDL of a web service)
...or any other technique that I may be missing?
And for completeness here is how I call these WebMethods from JQuery:
var jsondata = $.toJSON(data);
$.ajax({
type: "POST",
url: "MyWebPage.aspx/SaveComplexRecord",
data: jsondata,
contentType: "application/json; charset=utf-8",
dataType: "json",
beforeSend: function(xhr)
{
xhr.setRequestHeader("Content-type",
"application/json; charset=utf-8");
},
success: function(msg)
{
//do something on success
},
error: function(XMLHttpRequest, textStatus, errorThrown)
{
alert("ERROR status:" + textStatus + " error:" + errorThrown);
}
});
Or is there some utility that will automatically build the JSON parameter structure of a [WebMethod] call? (just like you can automatically get the WSDL of a web service)
Yes! The ASP.Net AJAX framework can do this! You could get the framework to generate client side proxy classes for GeneralData, SomeObject and SomeOtherObject classes using the 'GenerateScriptType' attribute on a web service class.
See understanding asp net ajax web servcies for a very good article about the subject.
[Unfortunately, AFAIAA, the GenerateScriptType has no effect when applied to the Page class where your page method is defined - so you will have to add an .asmx purely to get the proxy generation.]
You could perhaps use these classes to build up the data structure that you then JSON stringify when you call .ajax? [One of (the very few) things I really like about the MS AJAX framework is the client side proxy generation: it really does make calling web services and page methods very easy. Having said that, I too am moving towards using jQuery in preference to MS AJAX.]
Or alternatively...
Your problem is really that the de-serialisation of the JSON data into the arguments of your page method is done transparently by the framework (which in most cases is a good thing) but when it goes wrong, the feedback you get is less-than-helpful. If you want to trap de-serialisation problems then I think you have to take control of the serialisation either by using custom JSON converters (see here) or by using the rather inelegant sledgehammer approach of having your method accept a string and de serializing the JSN yourself in the method - which is trivial with anyone of the numerous JSON libs out there.
Javascript is dynamically typed so you can't get a compile-time error. But you could use the old window.onerror + ajax trick (or send the error via ajax in the error callback of jQuery.ajax()), and once you're in the server you can treat it just like any other runtime error (throw an exception, log the error, whatever)
From a jQuery standpoint, your problem is in the error function declaration. Only take one input parameter, and that will have all properties of the error, then you can debug more easily.
If the problem is server side, catch the error there, and create return json containing the error message.
Oh, and if you DO want to check your javascript at compile time, I recommend the add-in from jslint.com.
So:
$.ajax({
type: "POST",
url: "MyWebPage.aspx/SaveComplexRecord",
data: jsondata,
contentType: "application/json; charset=utf-8",
dataType: "json",
beforeSend: function(xhr)
{
xhr.setRequestHeader("Content-type",
"application/json; charset=utf-8");
},
success: function(msg)
{
//do something on success
},
error: function(err)
{
alert(e.message);
}
});
What I do when returning JSON from a web service is have an object called "ret" containing an attribute "err" as well as the attribute "data" containing the result of the service call. Inside the web service I trap any exceptions and put the exception message on the "err" attribute. Then in the client I check for the "err" attribute being non empty, if it is I know that an error occurred.
I'm trying to use jQuery and JSON with a C# Web Service that I wrote. No matter what, the following code will only output in XML.
Webservice Code
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string HelloWorld() {
return "Hello World!";
}
I also have these attributes assigned to the class
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
jQuery Code
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "ScheduleComputerDS.asmx/HelloWorld",
data: "{}",
dataType: "jsonp",
success: function(data) {
alert(data);
}
});
The ASMX page always returns as content type "text/xml". Anything I'm missing?
EDITS: In response to a couple answers:
If I have the datatype as just "json" the content is still XML and jQuery also will not call my callback function. If I add the "&callback=?" to the url, IIS throws a HTTP 500 error.
My class does inherit from "System.Web.Services.WebService".
From doing some research on your guys answers, it looks like I do need to mess with WCF. Unfortunately the JSON that is returned is more designed for MS Ajax and is a lot of useless bloat for my use. I may look into an open source library like Jayrock or something similar.
Thanks for all your help!
I think there's a typo:
dataType: "jsonp",
Should be:
dataType: "json",
As far as I know, the ScriptService attribute just allows the service to automatically create a JavaScript proxy (by appending /js to the endpoint address - ScheduleComputerDS.asmx/js in your case). It does not allow you to call the operations on the service the way you're trying to do.
You could instead use a RESTful WCF service (which requires .NET 3.5) which you can access by sending a properly shaped URI via an HTTP GET.
Rich Strahl has a really basic post that should help you out with this.
http://www.west-wind.com/weblog/posts/164419.aspx
Have you tried with datatype json?
Also, have a look at Encosia's Using jQuery to Consume ASP.NET JSON Web Services article on the matter. There's some good info on common pitfalls too.