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" };
}
Related
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));
OK, I know the easiest way to use Attribute Routing in MVC 6 is:
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
}
public void Configure(IApplicationBuilder app)
{
app.UseMvc();
}
}
And here is the controller code using the new Tokens (without Areas):
[Route("[controller]/[action]")]
public class HomeController : Controller
{
}
And here is the controller code using the new Tokens (with Areas):
[Area("MyArea")]
[Route("[controller]/[action]")]
public class HomeController : Controller
{
}
Questions:
Is this how MS wants you to code your controllers using Areas and Tokens?
Or is there a cleaner way?
Could they have somehow created an [area] Token?
Lastly, I know I can play this game, but isn't the 1st convention-based approach - app.UseMvc() - the simplest?
public void Configure(IApplicationBuilder app)
{
app.UseMvc(routes =>
{
routes.MapRoute(
name: "areaRoute",
template: "{area:exists}/{controller=Home}/{action=Index}/{id?}"
);
});
}
Microsoft gives you two options, each with own pros and cons. You should decide which one is better based on your context/needs.
Convention based routing
Pros:
It is simpler, instead of defining everything on an per-action level you just decide once and for all how your urls will looks like .
Perfect when your urls exactly match controller/action names.
If you want to change and url you need change the name of class/method.
Perfect for projects with clean and predictable url structure.
Perfect for quickly prototyping a new project.
Slightly easier for developers -> by knowing an url you know in which controller/action lies the functionality
Cons:
You loose little bit of control
Attribute-based routing
Pros:
Gives you total control over how the url looks like, for example for SEO purposes.
If you want to change an url you do not need to change the name of class/method.
Perfect when your urls do not match controller and action names or you want to hand-craft them (i.e customer wants that).
Perfect for maintaining backward compatibility, when you have an legacy project and want to have compatible url structure.
Cons:
Requires little bit more work, as you need to define the routes in your code. Please note that adding an attribute to a class/method is a matter of seconds.
How to decide which one to use:
If you have/expect to have very few routes.MapRoute() calls -> use convention routing as its simpler
If you have/expect to have lots of routes.MapRoute() calls -> use attribute routing
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?
I am looking at using WebAPI to create a Restful API. I want to create a launch url to provide URLs to the other portions/entities of the API. The obvious place to do this is ~/api/ however I cannot seem to wire up a route that will not give a 403 result. Any ideas?
EDIT: Just to be a bit clearer. I know how the default routing works in WebAPI, I.E. if I create a CustomersController that inherits from ApiController I can get there using ~/api/customers. What I want is a step before that where I could go to ~/api/ and would get a result a bit like:
[
{ Title: 'Customers', Url: '~/api/customers' }
]
I want this as my understanding is that RESTful services are metadata (think that the term) driven (basically discoverable and provide links to other resources in result). So there should be a single source url that points to all other resources in the API.
All you need to do for this is to add a new route which handles ~/api specifically.
In your project you will notice in the Application_Start method in the Global.asax a call is made to WebApiConfig.Register(GlobalConfiguration.Configuration), the WebApiConfig class is included in your project in the App_Start folder (along with various other config classes). If you look at the implementation of the Register call you will see that's where the ~/api/controller route is actually setup i.e.
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
In order to make ~/api discoverable all you need to do is introduce a new route before the default which handles any calls to ~/api e.g.
config.Routes.MapHttpRoute(
name: "DiscoverableApi",
routeTemplate: "api",
defaults: new { controller = "Discoverable", }
);
Then add an ApiController to handle that call e.g.
public class DiscoverableController : ApiController
{
// GET api/values
public IEnumerable<string> Get()
{
return new string[] { "/users", "/photos", "/history" };
}
}
If you don't want to hard-code your URLs you will most likely need to look at something like Reflection to enumerable all the available ApiController's and their reachable endpoints (i.e. actions).
Take a look at the Microsoft ASP.NET Web API Help Page package from NuGet. Out of the box you can create a list of all your API endpoints which are returned as an MVC View. However you could customise it to return Json instead. You can also configure it to hang off any route you want, i.e.
api.mysite.com/help
myapi.com/api
etc
The web api seems to be only suited for the standard use-cases.
But I want to do more complex routing but can't find documentation for complex routing.
If I have more controller, the routings gets more and more complicated.
Can i define several optional parameters with dependencies?
Like this:
/api/document/{par1}/{par2}
par1 & par2 should be optional but par2 should be only matched if par1 is present.
And are recursive parameters possible?
/api/documents/characteristics/{round/green/red-dots}
/api/documents/characteristics/{square/yellow}
/api/documents/characteristics/{square/yellow/flat}
/api/documents/characteristics/{square/yellow/flat/...}
Is there a detailed documentation for the web api routing? The microsoft tutorial is too basic...
I need more information about the routing.
I have two controllers and some trouble because two routings are quite similar, so the wrong route is taken. I can use [Action]-Attribute as a workaround, but this feels not right... I also have to consider the order of the routes. This is logical but is nowhere mentioned.
Is the web api only for simple rest api's?
Edit:
I tried this:
routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{mandant}/documents/{id}",
defaults: new { controller = "documents", id = RouteParameter.Optional }
);
//routes.MapHttpRoute(
// name: "DefaultApiWithAction",
// routeTemplate: "api/{mandant}/documents/{id}/{action}",
// defaults: new { controller = "documents" }
// );
I have two methods:
[AcceptVerbs("get")]
public HttpResponseMessage Get(int id)
[ActionName("file")]
[AcceptVerbs("get")]
public HttpResponseMessage filedownload(int id)
Now I have the problem, the file-action is triggered even if I comment out the second route and the normal get specific document method is not triggered because multiple actions... I tried the [NoAction] attribute but this is not working...
But why will the file-method be triggered if there is no action in the route-template? (Or if the second route is active, why will the normal get-document method not be triggered if there is no action in the url....)
I my current workaround is to set a default-action for all other methods, but this is not a good solution.
You can use routing constraints to set conditions on the routing in global.asax like:
routes.MapRoute(
"ApiRoute",
"api/document/{par1}/{par2}",
new {controller="Document", action="SomeMethod"},
new {par1 = #"\d+" }
);
In the last parameter you can specify regular expression that has to be matched for specified parameter for the route to be used. In the example above par1 is used for digits only, but you can use any regular expression, like:
routes.MapRoute(
"ApiRoute",
"api/document/{par1}/{par2}",
new {controller="Document", action="SomeMethod"},
new {par1 = #"(value1|value2|value3)" }
);