I'm upgrading a custom solution where I can dynamically register and unregister Web Api controllers to use the new attribute routing mechanism. However, it seems to recent update to RTM break my solution.
My solution exposes a couple of Web Api controllers for administration purposes. These are registered using the new HttpConfigurationExtensions.MapHttpAttributeRoutes method call.
The solution also allows Web Api controllers to be hosted in third-party assemblies and registered dynamically. At this stage, calling HttpConfigurationExtensions.MapHttAttributeRoutes a second time once the third-party controller is loaded would raise an exception. Therefore, my solution uses reflection to inspect the RoutePrefix and Route attributes and register corresponding routes on the HttpConfiguration object.
Unfortunately, calling the Web Api results in the following error:
"No HTTP resource was found that matches the request URI".
Here is a simple controller that I want to use:
[RoutePrefix("api/ze")]
public sealed class ZeController : ApiController
{
[HttpGet]
[Route("one")]
public string GetOne()
{
return "One";
}
[HttpGet]
[Route("two")]
public string GetTwo()
{
return "Two";
}
[HttpPost]
[Route("one")]
public string SetOne(string value)
{
return String.Empty;
}
}
Here is the first solution I tried:
configuration.Routes.MapHttpRoute("ZeApi", "api/ze/{action}");
Here is the second solution I tried:
var type = typeof(ZeController);
var routeMembers = type.GetMethods().Where(m => m.IsPublic);
foreach (MethodInfo method in routeMembers)
{
var routeAttribute = method.GetCustomAttributes(false).OfType<RouteAttribute>().FirstOrDefault();
if (routeAttribute != null)
{
string controllerName = type.Name.Substring(0, type.Name.LastIndexOf("Controller"));
string routeTemplate = string.Join("/", "api/Ze", routeAttribute.Template);
configuration.Routes.MapHttpRoute(method.Name, routeTemplate);
}
}
I also have tried a third solution, whereby I create custom classes that implement IHttpRoute and trying to register them with the configuration to no avail.
Is it possible to use legacy-style route mapping based upon the information contained in the new routing attributes ?
Update
I have installed my controller in a Web Application in order to troubleshoot the routing selection process with the Web Api Route Debugger. Here is the result of the screenshot:
As you can see, the correct action seems to be selected, but I still get a 404 error.
Update2
After further analysis, and per Kiran Challa's comment below, it seems that the design of Web Api prevents mixing attribute routing and conventional routing, and that what I want to do is not possible using this approach.
I have created a custom attribute [RouteEx] that serves the same purpose of the Web Api [Route] attribute, and now my code works perfectly.
I guess, since this is not possible using the conventional attribute routing, none of the answers on this question could legitimately be consisered valid. So I'm not nominating an answer just yet.
You shouldn't be required to use reflection and inspect the attribute-routing based attributes yourself. Attribute routing uses existing Web API features to get list of controllers to scan through.
Question: Before the switch to attribute routing, how were you loading these assemblies having the
controllers?
If you were doing this by IAssembliesResolver service, then this solution should work even with attribute routing and you should not be needing to do anything extra.
Regarding your Update: are you calling MapHttpAttributeRoutes?
Related
I commence in REST and I have some questions:
What type must the controller return? Typically, I'm asking if my Rest #Controller must return Item object as it is or encapsulate it in ResponseEntity in order to specify http-status-code.
What http status code to use in a GET method on a particular item ("/items/2") if the given item does not exists: HttpMediaStatus.OK(200) and null return or HttpStatus.NO_CONTENT(204) and null return ?
Second part: I saw it was possible to specify #Produces and #Consumes on WS method but what the use of that? My application and my methods work so, why specify MediaType.APPLICATION_JSON_VALUE? Doesn't Spring/SpringBoot automatically convert Item or ResponseEntity into json?
Context: using Spring Boot, hibernate, REST webservice.
Thank you.
Many questions in one, I'll provide short answers with a bunch of link to relevant articles and the reference documentation.
What type must the controller return?
Depends on your annotation and the RESTful-ness of your service. There are three annotations you can use for controllers: #Controller, #RestController and #RepositoryRestController.
Controller is the base annotation to mark your class as a controller. The return type of the controller endpoint methods can be many things, I invite you to read this dedicated post to get a grasp of it.
When developing a pure-REST service, you will focus on using RestController and RepositoryRestController.
RestControlleris Controller + ResponseBody. It binds the return value of the endpoint method to the web response body:
#RestController
public ItemController {
#RequestMapping("/items/{id}")
public Item getItem(#PathVariable("id") String id) {
Item item = ...
return item;
}
}
With this, when you hit http:/.../api/items/foo, Spring does its magic, automatically converting the item to a ResponseEntity with a relevant 40X status code and some default HTTP headers.
At some point, you will need more control over the status code and headers, while still benefiting from Spring Data REST's settings. That's when you will use RepositoryRestController with a ResponseEntity<Item> as return type, see the example the Spring Data REST reference.
What http status code to use in a GET method on a particular item if the given item does not exists?
Bluntly said: use HttpStatus.NOT_FOUND. You're looking for a resource that does not exist, there's something wrong.
That being said, it is completely up to you to decide how to handle missing resources in your project. If your workflow justifies it, a missing resource could be something completely acceptable that indeed returns a 20X response, though you may expect users of your API to get confused if you haven't warned them or provided some documentation (we are creatures of habits and conventions). But I'd still start with a 404 status code.
(...) #Produces and #Consumes on WS method but what the use of that? My application and my methods work so, why specify MediaType.APPLICATION_JSON_VALUE? Doesn't Spring/SpringBoot automatically convert Item or ResponseEntity into json?
#Consumes and #Produces are respectively matched against content-type and accept headers from the request. It's a mean of restricting the input accepted and the output provided by your endpoint method.
Since we're talking about a REST service, communications between clients of the API and the service are expected to be JSON-formatted. Thanks to Spring HATEOAS, the answer are actually formatted with the application/hal+json content-type.
In that scenario, you can indeed not bother with those two annotations. You will need them if you develop a service that accepts different content-types (application/text, application/json, application/xml...) and provides, for instance, HTML views to users of your website and JSON or XML response to automated clients of your service.
For real life examples:
Facebook provides the Graph API for applications to read to/write from its graph, while users happily (?) surf on web pages
Google does the same with the Google Maps API
I have an ASP.NET Web API I wrote and have published. Now that its out there we are looking at doing some improvements, and these improvements involve changes to certain calls which means we need to version to keep existing clients working.
I have used attribute routing so far in my app. Methods are invoked by: Controller/Action via RoutePrefix and Route attributes.
When I do need to create a V2 of my classes, I only want to recreate the classes that have actually changed, and redirect other routes back to v1 classes because they haven't changed. (Otherwise I just end up with a lot of boilerplate code, or duplicate code).
What I want to do is have the following routes work for my v1 version of classes:
Controller/Action
For V2 I want any new classes to go to V2, and any classes that haven't changed I want to return the HttpControllerDescriptor from V1 class. The route would look like v2/Controller/Action but would be redirected to Controller/Action.
I've implemented a IHttpControllerSelector and return the appropriate HttpControllerDescriptors but its not making the call into the method. I believe its because the routing information doesn't match the action. (When I put in an IHttpActionSelector and trace the exception it says "multiple actions were found that match the request).
So, I'm guess I'm wondering: Is this even possible? Is this the best way to achieve what I'm trying to do?
Here is what I implemented for versioning support in asp.net web api. Important to note I did not use attribute routing but explicit routes in WebApiConfig.cs so if you want to follow this pattern you would need to switch back to explicit routes. Also I do not prefer version information in the actual route, I use a custom (ie. "version") parameter in Accept header. I also set the version per mime type as in the below example. If version number is not set by the client or if the requested version does not exist this will fall back to default controller.
Create a class and inherit from DefaultHttpControllerSelector so you can fallback to base class behavior when you wanted to.
Override SelectController method as such:
public override HttpControllerDescriptor SelectController(HttpRequestMessage request)
{
IDictionary controllers = GetControllerMapping();
IHttpRouteData routeData = request.GetRouteData();
string controllerName = (string)routeData.Values["controller"];
HttpControllerDescriptor controllerDescriptor;
if (string.IsNullOrWhiteSpace(controllerName))
{
return base.SelectController(request);
}
if (!controllers.TryGetValue(controllerName, out controllerDescriptor))
{
return null;
}
string version = GetVersionFromAcceptHeader(request);
if (string.Equals(version, "1"))
{
return controllerDescriptor;
}
string newName = string.Concat(controllerName, "V", version);
HttpControllerDescriptor versionedControllerDescriptor;
if (controllers.TryGetValue(newName, out versionedControllerDescriptor))
{
return versionedControllerDescriptor;
}
return controllerDescriptor;
}
Register this controller selector in your webapiconfig Register method:
config.Services.Replace(typeof(IHttpControllerSelector), new YourControllerSelector(config));
I'm very confused about the design of my RESTful services!
If I was doing this using vanilla MVC3/4 then I would simply have action methods marked [HTTPGet] etc. and I could have multiple Get's per controller. I this way I would organise controllers by their "meta group".
I've looked at the Web API MVC4 template and it gives me the automatic translation from an Http GET to the Getxxx() method - but this implies a single Get per controller and organising controllers by object, rather than function...which seems to make some sense.
I see many posts on adding named routes - but this seems to break the natural model of Get, Post, Put, Delete. If I do that - then aren't I (in essence) just going back to vanilla MVC4?
Is there any impact on having lots of controllers?
Am I thinking
about this correctly?
Shortly,
Is there any impact on having lots of controllers?
No
Am I thinking about this correctly?
Generally yes.
Default WebAPI/MVc template uses routing that relays on prefixes and naming GetXXX, PostXX.
RouteTable.Routes.MapRoute(
"WithActionApi",
"api/{controller}/{action}/{id}"
);
But you can create your own custom routing with action names instead. Then you uses in URL name of your action method and as you've wrote Attributes to set HTTP Verbs like [HttpGet]
RouteTable.Routes.MapRoute(
"DefaultApi",
"api/{controller}/{id}",
new { action="DefaultAction", id = System.Web.Http.RouteParameter.Optional }
);
[ActionName("DefaultAction")] //Map Action and you can name your method with any text
public string Get(int id)
{
return "object of id id";
}
[HttpGet]
public IEnumerable<string> ByCategoryId(int id)
{
return new string[] { "byCategory1", "byCategory2" };
}
I am using the Asp.Net Web Api. I would like to be able to filter out certain fields on the response objects based on the connected clients access rights.
Example:
class Foo
{
[AccessFilter("Uberlord")]
string Wibble { get; set; }
string Wobble { get; set; }
}
When returning data the filed Wibble should only be returned if the current users context can satisfy the value of "Uberlord".
There are three avenues that I am exploring but I have not got a working solution:
A custom WebApi MediaTypeFormatter.
A custom json.net IContractResolver.
Some sort of AOP wrapper for controllers that manipulates the response object
My issue with these are:
The custom formatter does not feel like the right place to do it but might be the only option.
The custom json serializer would not have access to the current context so I would have to work that out.
With the first two options you would require specific implementations for each response format, json, xml, some custom format, etc. This would mean that if another response type is supported then a custom formatter / serializer is required to prevent sensitive data leaking.
The AOP controller wrapper would require a lot of reflection.
An additional bonus would be to strip out values from the fields on an inbound request object using the same mechanism.
Have I missed an obvious hook? Has this been solved by another way?
It was actually a lot simpler than I first thought. What I did not realise is that the DelegatingHandler can be used to manipulate the response as well as the request in the Web Api Pipeline.
Lifecycle of an ASP.NET Web API Message
Delegating Handler
Delegating handlers are an extensibility point in the message pipeline allowing you to massage the Request before passing it on to the rest of the pipeline. The response message on its way back has to pass through the Delegating Handler as well, so any response can also be monitored/filtered/updated at this extensibility point.
Delegating Handlers if required, can bypass the rest of the pipeline too and send back and Http Response themselves.
Example
Here is an example implementation of a DelegatingHandler that can either manipulate the response object or replace it altogether.
public class ResponseDataFilterHandler : DelegatingHandler
{
protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
return base.SendAsync(request, cancellationToken)
.ContinueWith(task =>
{
var response = task.Result;
//Manipulate content here
var content = response.Content as ObjectContent;
if (content != null && content.Value != null)
{
((SomeObject)content.Value).SomeProperty = null;
}
//Or replace the content
response.Content = new ObjectContent(typeof(object), new object(), new JsonMediaTypeFormatter());
return response;
});
}
}
Microsoft article on how to implement a delegating handler and add it to the pipeline.HTTP Message Handlers in ASP.NET Web API
I have a similar question in the works over here: ASP.NET WebAPI Conditional Serialization based on User Role
A proposed solution that I came up with is to have my ApiController inherit from a BaseApiController which overrides the Initalize function to set the appropriate formatter based on the user's role. I haven't decided if I will go this way yet, but perhaps it will work for you.
protected override void Initialize(System.Web.Http.Controllers.HttpControllerContext controllerContext)
{
base.Initialize(controllerContext);
// If the user is in a sensitive-data access role
controllerContext.Configuration.Formatters.Add(/*My Formatter*/);
// Otherwise use the default ones added in global app_start that defaults to remove sensitive data
}
I'm trying to build a REST service in a Sitecore root. My application start looks like this:
void Application_Start(object sender, EventArgs e)
{
RouteTable.Routes.MapHttpRoute(
name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = System.Web.Http.RouteParameter.Optional });
}
And my URL looks like this:
http://{mydomain}/api/books
I have the correct controller and all that.
But Sitecore keeps redirecting me to the 404 page. I've added the path to the IgnoreUrlPrefixes node in the web.config, but to no avail. If I had to guess, I'd think that Sitecore's handler is redirecting before my code gets the chance to execute, but I really don't know.
Does anybody have any idea what might be wrong?
Your assessment is correct. You need a processor in the httpRequestBegin pipeline to abort Sitecore's processing. See the SystemWebRoutingResolver in this answer:
Sitecore and ASP.net MVC
It's also described in this article:
http://www.sitecore.net/Community/Technical-Blogs/John-West-Sitecore-Blog/Posts/2010/10/Sitecore-MVC-Crash-Course.aspx
But I'll include the code here as well. :)
public class SystemWebRoutingResolver : Sitecore.Pipelines.HttpRequest.HttpRequestProcessor
{
public override void Process(Sitecore.Pipelines.HttpRequest.HttpRequestArgs args)
{
RouteData routeData = RouteTable.Routes.GetRouteData(new HttpContextWrapper(args.Context));
if (routeData != null)
{
args.AbortPipeline();
}
}
}
Then in your httpRequestBegin configuration:
<processor type="My.SystemWebRoutingResolver, My.Classes" />
You might want to have a look at Sitecore Web Api
It's pretty much the same you are building.
Another option, which I've used to good effect, is to use the content tree, the "star" item, and a sublayout/layout combination dedicated to this purpose:
[siteroot]/API/*/*/*/*/*/*/*/*/*
The above path allows you to have anywhere between 1 and 9 segments - if you need more than that, you probably need to rethink your process, IMO. This also retains all of the Sitecore context. Sitecore, when unable to find an item in a folder, attempts to look for the catch-all star item and if present, it renders that item instead of returning a 404.
There are a few ways to go about doing the restful methods and the sublayout (or sublayouts if you want to segregate them by depth to simplify parsing).
You can choose to follow the general "standard" and use GET, PUT, and POST calls to interact with these items, but then you can't use Sitecore Caching without custom backend caching code). Alternately, you can split your API into three different trees:
[siteroot]/API/GET/*/*/*/*/*/*/*/*/*
[siteroot]/API/PUT/*/*/*/*/*/*/*/*/*
[siteroot]/API/POST/*/*/*/*/*/*/*/*/*
This allows caching the GET requests (since GET requests should only retrieve data, not update it). Be sure to use the proper caching scheme, essentially this should cache based on every permutation of the data, user, etc., if you intend to use this in any of those contexts.
If you are going to create multiple sublayouts, I recommend creating a base class that handles general methods for GET, PUT, and POST, and then use those classes as the base for your sublayouts.
In your sublayouts, you simply get the Request object, get the path (and query if you're using queries), split it, and perform your switch case logic just as you would with standard routing. For PUT, use Response.ReadBinary(). For POST use the Request.Form object to get all of the form elements and iterate through them to process the information provided (it may be easiest to put all of your form data into a single JSON object, encapsulated as a string (so .NET sees it as a string and therefore one single property) and then you only have one element in the post to deserialize depending on the POST path the user specified.
Complicated? Yes. Works? Yes. Recommended? Well... if you're in a shared environment (multiple sites) and you don't want this processing happening for EVERY site in the pipeline processor, then this solution works. If you have access to using MVC with Sitecore or have no issues altering the pipeline processor, then that is likely more efficient.
One benefit to the content based method is that the context lifecycle is exactly the same as a standard Sitecore page (logins, etc.), so you've got all the same controls as any other item would provide at that point in the lifecycle. The negative to this is that you have to deal with the entire page lifecycle load before it gets to your code... the pipeline processor can skip a lot of Sitecore's process and just get the data you need directly, making it faster.
you need to have a Pipeline initializer for Routing:
It will be like :
public class Initializer
{
public void Process(PipelineArgs args)
{
RouteCollection route = RouteTable.Routes;
route.MapHttpRoute("DefaultApi", "api/{controller}/{action}/{id}",
new { id = RouteParameter.Optional });
}
}
On config file you will have :
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
<sitecore>
<pipelines>
<initialize>
<processor type="_YourNameSpace.Initializer,_YourAssembly" />
</initialize>
</pipelines>
</sitecore>
</configuration>
Happy coding