I'm currently watching a video course about ASP.NET Web API. When a controller gets called, the data gets returned in JSON by default. I was just wondering, because when I copy this sample project from the video, I get XML.
The frustration is big, please help me to solve this.
I'm pretty new to ASP.NET Web API, so please bear with me.
UPDATE
The controller doesn't contain special code. It's the simple code, which gets generated from the API Controller with empty read/write actions template.
ASP.NET WebAPI comes with built-in content negotitation therefore the format of the return value is determined by the request itself - more specifically by the Accept/Content-Type headers (depending on which ones are present, Accept header appears to be favoured over the Content-type).
I assume you're viewing the results in a browser and by default it's probably asking for application/xml. You will need to toy around with some settings/developer tools on the browser and force it to send Content-Type: application/json to get the correct response (assuming your returning HttpResponseMessage).
in Global.asax: add the line:
GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
It'll look like this.
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
RegisterGlobalFilters(GlobalFilters.Filters);
RegisterRoutes(RouteTable.Routes);
BundleTable.Bundles.RegisterTemplateBundles();
GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();
}
James is close, but the content negotiation actually uses the [Accept] header,
not [Content-Type]
As with nearly everything else in MVC, you can override the content negotiation components to ensure the desire content is returned
W3c clearly states-
14.1 Accept
The Accept request-header field can be used to specify certain media types which are acceptable for the response.
-and-
14.17 Content-Type
The Content-Type entity-header field indicates the media type of the entity-body sent to the recipient or, in the case of the HEAD method, the media type that would have been sent had the request been a GET.
This page headers is very useful to understand request/response negotiation.
Related
When nothing is specified in "accept" header in the request, why is XML response returned by default in Web API? I mean is there anything which makes the framework to do so?
XmlMediaTypeFormatter is the default formatter, as this is the order in which they are found in the 'Formatters' collection of the HttpConfiguration object
https://stackoverflow.com/a/20192316/1538039
You can change the behaviour here by clearing down and only adding in a Jsonformatter, e.g.
configuration.Formatters.Clear();
configuration.Formatters.Add(new JsonMediaTypeFormatter());
The link to StrathWeb contains additional information
I am using valums file-uploader to upload files. This works great if my Spring controller returns void. If I add a #Responsebody Object to my controller IE things that I am about to download instead of uploading a file and launches a dialog.
The reason I would like to have a #Responsebody Object and not void is for error handling. How can I trick IE in this case?
I'm assuming that Spring is automagically setting the content-type to application/json for you, which will not work in IE. Ensure the content-type of your response is text/plain. Some will say that text/html is correct, and that is true for most cases. However, text/html will cause you problems if your JSON response contains HTML as IE will mess with the response. So, your safest bet is to ensure the content-type of your response is text/plain.
While we are on the topic of IE quirkiness, also be sure that you only return a 200 response if you intend to also include JSON in your response. IE will, by default, replace the content of "small" non-200 responses with a "friendly" message. "Small", I believe, is defined as a response that is less than 512 (or possibly 256) bytes.
For a list of all things you should be aware of when using IE, have a peek at the "limitations of IE" section in the Fine Uploader readme.
I am using jqgrid in my ASP.NET MVC application. Currently I have mTYpe: 'POST' like this:
jQuery("#myGrid").jqGrid({
mtype: 'POST',
toppager: true,
footerrow: haveFooter,
userDataOnFooter: haveFooter,
But I was reading this article, and I see this paragraph:
Browsers can cache images, JavaScript, CSS files on a user's hard
drive, and it can also cache XML HTTP calls if the call is a HTTP GET.
The cache is based on the URL. If it's the same URL, and it's cached
on the computer, then the response is loaded from the cache, not from
the server when it is requested again. Basically, the browser can
cache any HTTP GET call and return cached data based on the URL. If
you make an XML HTTP call as HTTP GET and the server returns some
special header which informs the browser to cache the response, on
future calls, the response will be immediately returned from the cache
and thus saves the delay of network roundtrip and download time.
Given this is the case, should I switch my jqGrid mType all to use "GET" from "POST" for the mType? (It says XML (doesn't mention JSON). If the answer is yes, then actually what would be a situation why I would ever want to use POST for jqGrid mType as it seems to do the same thing without this caching benefit?
The problem which you describe could be in Internet Explorer, but it will be not exist in jqGrid if you use default options.
If you look at the full URL which will be used you will see parameters like
nd=1339350870256
It has the same meaning as cache: true of jQuery.ajax. jqGrid add the current timestemp to the URL to make it unique.
I personally like to use HTTP GET in jqGrid, but I don't like the usage of nd parameter. The reason I described in the old answer. It would be better to use prmNames: {nd:null} option of jqGrid which remove the usage of nd parameter in the URL. Instead of that one can control the caching on the server side. For example the setting of
Cache-Control: private, max-age=0
is my standard setting. To set the HTTP header you need just include the following line in the code of ASP.NET MVC action
HttpContext.Current.Response.Cache.SetMaxAge (new TimeSpan (0));
You can find more details in the answer.
It's important to understand, that the header Cache-Control: private, max-age=0 don't prevent the caching of data, but the data will be never used without re-validation on the server. Using other HTTP header option ETag you can make the revalidate really working. The main idea, that the value of ETag will be always changed on changing the data on the server. In the case if the previous data are already in the web browser cache the web browser automatically send If-None-Match part in the HTTP request with the value of ETag from the cached data. So if the server see that the data are not changed it can answer with HTTP response having 304 Not Modified status and empty body of the HTTP response. It allows the web browser to use local previously cached data.
In the answer and in this one you will find the code example how to use ETag approach.
If the data that the server sends changes, then you should use POST to avoid getting cached data everytime you request it.
You should not use GET for all the purposes. GET requests are supposed to use for getting data from the server not for saving or deleting operation. GET requests has some limitation since the data you are sending to the server or appended as query-strings you can't send very large data using GET requests. Also you should not use GET request to send sensitive information to the server. You should the POST request in all the other cases like adding, editing and deleting.
As far as I'm aware jqgrid appends a unique key in every GET request so you don't get any benefit from browser caching.
One way around the caching behavior is to make the GET unique each time the request is made. jQuery.ajax() does this with "cache: false" by appending a timestamp to the end of the request. You can replicate this behavior with something similar:
uri = uri + '?_=' + (new Date()).getTime(); // uri represents the URI to the endpoint
When you want to put your site offline.
Almost everything in our application (API) is JSON. I think it might be better to return JSON, as the programs build on top of this API expects a JSON response on all of the methods.
Is it possible to return JSON instead with the correct content type in the App_Offline.htm?
Have you tried removing the ContentType header and adding it after :
http://i2.iis.net/ConfigReference/system.webServer/httpProtocol/customHeaders
I have never done that with app_offline.htm but might work.
Title sums it up fairly well.
Said site has cookies, I need to post data from a textbox as a value on said site, and get one of two variables back. I was reading through some tutorials and a few Windows phone 7 books. None of them were related to what I was trying to do. They only dealt with single whole files or something that could be made into a URL. I could also do it that way if someone had a way to also use cookies and just send it as a url [but i do not know how to construct the url in such a way to make that a realistic solution].
You should be able to send cookie's using code like:
CookieContainer container = new CookieContainer();
container.Add(new Uri("http://yoursite"), new Cookie("name", "value"));
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://yoursite");
request.CookieContainer = container;
request.BeginGetResponse(new AsyncCallback(GetData), request);
Code borrowed from HttpWebRequest and Set-Cookie header in response not parsed (WP7)
If the server is expecting to use cookies (e.g. for authentication) then there is no way that you'll be able to use form variables/query parameters instead.
You need to use a tool called Fiddler to inspect the calls that the website currently makes - this will include a mixture of:
cookie variables - especially for authentication
get variables - passed within the url path
and post variables - passed within the body of the request
If you do need to do a full POST, then you will need to set variables like - request.Method and request.ContentType - and you will need to brovide a RequestStream. There are libraries you can use like HAMMOCK to help - or I've got some example code in iron7 - see the DoCodePost method at the botom of this uploader class - or take a look at lots of other projects on CodePlex and GitHub.