Response.Write() in WebService - asp.net

I want to return JSON data back to the client, in my web service method. One way is to create SoapExtension and use it as attribute on my web method, etc. Another way is to simply add [ScriptService] attribute to the web service, and let .NET framework return the result as {"d": "something"} JSON, back to the user (d here being something out of my control). However, I want to return something like:
{"message": "action was successful!"}
The simplest approach could be writing a web method like:
[WebMethod]
public static void StopSite(int siteId)
{
HttpResponse response = HttpContext.Current.Response;
try
{
// Doing something here
response.Write("{{\"message\": \"action was successful!\"}}");
}
catch (Exception ex)
{
response.StatusCode = 500;
response.Write("{{\"message\": \"action failed!\"}}");
}
}
This way, what I'll get at client is:
{ "message": "action was successful!"} { "d": null}
Which means that ASP.NET is appending its success result to my JSON result. If on the other hand I flush the response after writing the success message, (like response.Flush();), the exception happens that says:
Server cannot clear headers after HTTP headers have been sent.
So, what to do to just get my JSON result, without changing the approach?

This works for me:
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void ReturnExactValueFromWebMethod(string AuthCode)
{
string r = "return my exact response without ASP.NET added junk";
HttpContext.Current.Response.BufferOutput = true;
HttpContext.Current.Response.Write(r);
HttpContext.Current.Response.Flush();
}

Why don't you return an object and then in your client you can call as response.d?
I don't know how you are calling your Web Service but I made an example making some assumptions:
I made this example using jquery ajax
function Test(a) {
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "TestRW.asmx/HelloWorld",
data: "{'id':" + a + "}",
dataType: "json",
success: function (response) {
alert(JSON.stringify(response.d));
}
});
}
And your code could be like this (you need to allow the web service to be called from script first: '[System.Web.Script.Services.ScriptService]'):
[WebMethod]
public object HelloWorld(int id)
{
Dictionary<string, string> dic = new Dictionary<string, string>();
dic.Add("message","success");
return dic;
}
In this example I used dictionary but you could use any object with a field "message" for example.
I'm sorry if I missunderstood what you meant but I don't really understand why you want to do a 'response.write' thing.
Hope I've helped at least. :)

Related

Strange Behavior when using jQuery/asp.net WebApi

I have 2 Web API Projects:
Api1 is a testing-Environment for the JavaScript Front-End, but has a API
Back-end(the default ValuesController), also for testing.
Api2 is the "true" Back-end, from which the Experimental JavaScript UI schould pull Data. For Testing, i use the default ValuesController here too, because, i want to have the same Output.
Status Quo
The Api1-UI can query the Data from the ValuesController of the own API
The Api2 returns the Correct Data(tested in Firefox and with Fiddler)
The Code
JavaScript Client:
var _load = function (url) {
$.ajax({
url: url,
method: 'GET',
accepts: "application/json; charset=utf-8",
success: function (data) {
alert("Success: " + data);
},
error: function (data) {
alert("Error :" + data);
}
});
};
WebApi Controller method:
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}
Problem
The JavaScript UI of the experimental Front-End is not able to display, or even receive, the data from the API 2, which is, according to Fiddler, sent correct.
My first thought was, I am using the wrong Method, but i tried $.getJSON and $.ajax. But i always end up with an error. It just says statusText= "Error"
I don't get, why it can display Data from the own ApiController, but not from the "External"...
Thanks for any Help/Suggestions
You seem to be accessing data from X from a different domain Y using ajax. This seems to be a classic cross domain access issue.
You need to set Access-Control-Allow-Origin to value " * " in your response header.
Response.Headers.Add("Access-Control-Allow-Origin", "*")
There various ways you can solve this
defining this header in IIS
using a actionfilter attribute like below
FilterAttribute
public class AllowCrossSiteJsonAttribute : ActionFilterAttribute
{
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
if (actionExecutedContext.Response != null)
actionExecutedContext.Response.Headers.Add("Access-Control-Allow-Origin", "*");
base.OnActionExecuted(actionExecutedContext);
}
}
Using Attribute on Controller Action
[AllowCrossSiteJson]
public Result Get(int id)
{
//return appropriate result
}

How to call non static method from AJAX?

Here is my code behind I am calling from AJAX...
[WebMethod]
[ScriptMethod]
public static string save(string parameter)
{
country_master obj_country = new country_master();
obj_country.Country_Name = Page.Request.Params["name"].ToString().Trim();
obj_country.saved();
return "";
}
Here I am not able to access parameters passed from the page via Page.Request.
string name = HttpContext.Current.Request.QueryString["name"].Trim();
return "error";
after writing the first line, return statement does not return anything to the AJAX.
Please Help me how to do that.
Thanks...
To get the current context you can use HttpContext.Current, which is a static property.
Once you have that you can access things like session or profile and get information about the state of the site
HttpContext.Current.Session etc..
This link may help you : Call Server Side via AJAX without a Static Method
The reason behind restricting the web method to be static is to avoid it access the controls of the instance page.
Yo could use the HttpContext.Current static class, however you can skip that if you declare on your method the parameters you want to use and just pass the parameters with your AJAX call
You should pass parameters directly to the method.
I have several working examples on my Github repository, feel free to browse the code.
As a summary, to call a PageMethod:
Note: how using AJAX the jobID PageMethod parameter is being passed along with the request and how is used inside the PageMethod transparently
AJAX call
$.ajax({
type: 'POST',
url: '<%: this.ResolveClientUrl("~/Topics/JQuery/Ajax/PageMethods_JQueryAJAX.aspx/GetEmployees") %>',
contentType: 'application/json; charset=utf-8',
dataType: 'json',
data: '{"jobID" : ' + jobID +'}',
async: false,
cache: false,
success: function (data) {
$('#employees').find('option').remove();
$.each(data.d, function (i, item) {
$('<option />').val(item.EmployeeID).text(item.FirstName).appendTo('#employees');
});
},
error: function (xhr) {
alert(xhr.responseText);
}
});
Page Method
[WebMethod]
public static List<EmployeeModel> GetEmployees(int jobID)
{
var ctx = new PubsDataContext();
return (from e in ctx.employee
where e.job_id == jobID
orderby e.fname
select new EmployeeModel
{
EmployeeID = e.emp_id,
FirstName = e.fname
}).ToList();
}

Cross Domain Access to ashx service using jQuery

I have an ASP.NET service that I'm access from a asxh file that returns a JSON string. The service works great except when accessed from our blog sub domain which is on a separate server. (blog.laptopmag.com)
Here is my jQuery
$.ajax({
type: "GET",
url: "http://www.laptopmag.com/scripts/service.ashx",
data: { "op": "get_products" },
dataType: "json",
success: function (data) {
alert(data);
}
});
and here is my ashx file
public class service : IHttpHandler {
public void ProcessRequest (HttpContext context) {
string jsonStr = "{}";
string op = context.Request["op"];
// Process request
context.Response.ContentType = "application/json";
context.Response.Write(jsonStr);
}
public bool IsReusable {
get {
return false;
}
}
}
I've tried switching to a jsonp request, but must be doing something wrong because I can't get anything to pull back. Here is what I've tried.
and here is my jsonp attempt that doesn't seem to work when called from blog.laptopmag.com
$.getJSON('http://www.laptopmag.com/scripts/service.ashx?callback=ProcessRequest&op=get_products', function(json) {
console.log(json);
});
OK, I figured out what the problem was with my JSONP request thanks to the following post:
Jquery success function not firing using JSONP
The problem was that the request wasn't getting a response back in the expected format.
Now, my ashx file now looks like this:
public void ProcessRequest (HttpContext context) {
string jsonStr = "{}";
string op = context.Request["op"];
string jsonp = context.Request["callback"];
// Do something here
if (!String.IsNullOrEmpty(jsonp))
{
jsonStr = jsonp + "(" + jsonStr + ")";
}
context.Response.ContentType = "application/json";
context.Response.Write(jsonStr);
}
and the jQuery ajax request looks like this:
$.getJSON('http://www.laptopmag.com/scripts/service.ashx?callback=?&op=get_products', function(json) {
console.log(json);
});
Security restrictions prevent you from making cross-domain jquery ajax calls, but there are workarounds. IMO the easiest way is to create a page on your site that acts as a proxy and hit the page with your jquery request. In page_load of your proxy:
WebClient client = new WebClient ();
Response.Write (client.DownloadString ("your-webservice-url"));
Other solutions can be found by a quick Google search.

Pass JSON to MVC 3 Action

I am trying to submit JSON to a MVC action. What I want is to take the JSON object and then access it's data. The number of JSON fields will vary each time so I need a solution that will handle all cases.
This is my POST to my action, address could have 3 fields or 20 it will vary on each post.
Update: I'll go into a little more detail. I'm trying to use the LinkedIn API, I'll be sent a JSON which will look like the JSON at the end of this page : link. I need to create an Action which will accept this JSON which will vary for every person.
var address =
{
Address: "123 rd",
City: "Far Away",
State: "Over There"
};
$.ajaxSetup({ cache: false });
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "/Account/GetDetails/",
data: JSON.stringify(address),
dataType: "json",
success: function () {
alert("Success from JS");
}
});
This is my action in MVC, I need to be apply to take whatever JSON object is passed and access its fields.
[HttpPost]
public ActionResult GetDetails(object address)
{
//address object comes in as null
#ViewBag.Successs = true;
return View();
}
I don't believe nobody saying this so I will try. Have your code like this
public class Personal
{
public string Address { get; set; }
public string City { get; set; }
public string State { get; set; }
//other properties here
}
[HttpPost]
public ActionResult GetDetails(Personal address)
{
//Should be able to get it.
#ViewBag.Successs = true;
return View();
}
In general, you can add those possible properties into the class Personal (or whatever you can name it). But according to linkedin API, you will need a tool to generate the data class due to its complexity. I think xsd.exe can help if you can get xsd file for that (or you can even generate xsd file from xml)
Remove data: JSON.stringify(address) with data: address
Action method
[HttpPost]
public ActionResult GetDetails(string Address, string City, string State, string PropName)
{
//access variable here
}
As you have said your data object may contain 20 props, to avoid creating 20 parameters, you can use formscollection like below
[HttpPost]
public ActionResult GetDetails(FormCollection address)
{
string city= address["city"] ;
string anotherPro=address["prop"];
}
Not sure if this will work (never done this myself), but you could try the following signature:
public ActionResult LinkedIn(dynamic address)
I'm actually quite interested myself to see what will happen then. Or, as suggested in the comment by Kristof Claes, use a FormCollection.
Second, when things like this happen, always check whether the browser actually sends the data you expected to the server. IE9 and Chrome support this out of the box, otherwise you can use a tool like Fiddler.
EDIT: Just tried for myself with a dynamic parameter and that doesn't work.. The runtime type of the parameter is object so everything you submitted is lost. You'd better
use FormCollection.
I believe you can use a FormCollection for this.
public ActionResult LinkedIn(FormCollection address)
{
var street = address["street"];
...
return View();
}
Might just be a typo, but you are calling GetDetails ActionResult, but yet your code is LinkedIn ?
You need to wrap your JSON object in the name of parameter you are expecting in your action method. Something like this:
var data = { address: { address: '123 Test Way', city: 'Parts Unknown', state: 'TX' } };
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "/Account/GetDetails/",
data: JSON.stringify(data),
dataType: "json",
success: function () {
alert("Success from JS");
}
Then in your action method, do this:
public ActionResult GetDetails(dynamic address) {}
My take is all the answers are sort of right.
As your don't know the number of things you're sending, use formcollection on the server. But also remove the stringfy from the ajax call. These means the data will be sent using www-encoding.
If you wnat to send n address objects, change the mvc action parameter to an array of address objects and use stringfy.
This is how I do it. I have a MyProject.Model.Entities and I serialize them in by using [ParamSerializationFilter] attribute on the given action method.
Full code here: https://gist.github.com/3b18a58922fdd8d5a963
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (!Enum.GetNames(typeof(AllowedMethods)).Any(n => n == filterContext.HttpContext.Request.HttpMethod))
throw new InvalidOperationException("Invalid Request: HttpMethod");
foreach (var param in filterContext.ActionDescriptor.GetParameters())
{
if (ModelTypes.Contains(param.ParameterType))
{
if ((filterContext.HttpContext.Request.ContentType ?? string.Empty) == ("application/json"))
{
filterContext.ActionParameters[param.ParameterName] =
JsonSerializer.DeserializeFromStream(param.ParameterType, filterContext.HttpContext.Request.InputStream);
}
else if (filterContext.HttpContext.Request.ContentType.Contains("xml"))
{
filterContext.ActionParameters[param.ParameterName] =
XmlSerializer.DeserializeFromStream(param.ParameterType, filterContext.HttpContext.Request.InputStream);
}
}
}
}
You're doing too much work! You can pass the JSON Literal directly to the server and access the elements via the action method parameters, like this:
var address =
{
Address: "123 rd",
City: "Far Away",
State: "Over There"
};
$.ajaxSetup({ cache: false });
$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "/Account/GetDetails/",
data: address,
dataType: "json",
success: function () {
alert("Success from JS");
}
});
[HttpPost]
public ActionResult LinkedIn(string Address, string City, string State)
{
// now you have everything you want as params
#ViewBag.Successs = true;
return View();
}
Note: This will only work if your action params are named the exact same as your JSON Literal attributes.

Escaped JSON response with [WebMethod]

The JSON response from the following code is wrongly escaped as described below.
My webmethod is like this:
[WebMethod (Description="doc here")]
[ScriptMethod(ResponseFormat=ResponseFormat.Json)]
public string responseMyObject() {
if (!Setup()) return "";
...
Proxy pu = new Proxy(...);
...
string toReturn = JavaScriptConvert.SerializeObject(pu.getMyObject());
Console.WriteLine(toReturn);
return toReturn;
}
from the console I get:
{"field1":vaule1,"field2":value2}
from JS:
$.ajax({
type: "POST",
url: "/myapi/myClass.asmx/responseMyObject",
data: "{}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
var object = msg.d;
alert(object.field1);
}
});
The problem is that in the HTTP response header I can see that the JSON response is wrongly (?) escaped in the following way:
{"d":"{\"field1\":value1,\"field2\":value2}"}
What's strange is that the console print is fine (but not yet encapsulated in {d: ...}
{"field1":value1,"field2":value2}
With similar code, if I call a [WebMethod] that returns basic types (no object) the JSON response is ok. Like:
{"d":8080}
[WebService]
[ScriptService]
public class MyWebService : WebService
{
[WebMethod (Description="doc here")]
[ScriptMethod( UseHttpGet=false, ResponseFormat=ResponseFormat.Json)]
public MyObjectType responseMyObject()
{
Proxy pu = new Proxy(...);
return pu.GetMyObject();
}
}
You dont need a JSON serializer, tagging it with the ScriptService attribute gives it tie ability to serialize JSON out. You were pre serializing the JSON and then serializing it again :(
Why are you calling JavaScriptConvert.SerializeObject?
Can't you just change the return type of your method to be the type returned by pu.getMyObject() and the framework will do the rest?
In other words...
[WebMethod (Description="doc here")]
[ScriptMethod(ResponseFormat=ResponseFormat.Json)]
public MyObjectType responseMyObject()
{
Proxy pu = new Proxy(...);
...
return pu.GetMyObject();
}
At the moment I think you're serializing your object into a JSON format and then, when you return from the method, the framework is serializing that string (which contains JSON formatted data) into a JSON format.

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