Creating a REST service in Sitecore - rest

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

Related

REST URL for transforming one resource into another resource

I am struggling to come with proper REST URL for converting one resource into another. The API method does not do any CRUD operations but instead transform/convert one resource into another type of resource.
I have 2 resources Workunit and Document. I have 3 operations on these two resources
1> trasform Workunit into Document
2> sync Workunit into Document (different logic than transform)
3> transform Document into Workunit
and i have the following urls
[POST] api/v1/workunits/transform
[POST] api/v1/workunits/sync
[POST] api/v1/documents/transform
problem here is action is a part of REST URL
any suggestions?
problem here is action is a part of REST URL
That's not a problem - clients don't depend on the URL for semantics, so you can use any spelling you like; api/v1/4dc233fa-c77c-49d7-b7d6-296ffeb89612 is perfectly satisfactory.
It's analogous to having a verb as a variable name -- it may not be in keeping with your local coding standards, but the compiler doesn't care. So too is it with your URL and the general purpose components that use it.
Choosing a good identifier is like choosing a good name; it requires having a clear understanding of what the thing is. In the case of URI/URL, the thing being identified is a resource, which is to say something that is described by a document. GET/POST/PUT/DELETE and so on are all requests that we do something interesting with the underlying document.
So the usual pattern might be to POST a transform message to the workunit resource, or to POST a transform message to the Document resource, or to POST a sync message to the workunit resource.
Hmm, that last one sounds backwards; if the workunit is unchanged, and the Document is changed by the sync, then you would probably send a sync message to the Document resource.
So if I have /api/v1/documents/1, and I need to sync it, then I would normally use POST /api/v1/documents/1, with the sync semantics described in the message body (on the web, that would usually be an application/x-www-form-urlencoded representation of the sync message).
But it could just as easily be a message that says "Sync documents/1 with workitem/2" that I POST to the todo list for the synchronizer.
We are just putting documents politely into the server's in-tray, so that it can do useful work. The in-tray can have whatever label you want.
It is fine with given situation.
Nevertheless, if I am getting you right it may be a good idea to create two different controllers.
It's up to you but think of changing structure a little bit:
Separate the logic of Transformation and Sync into two different controllers, so you can avoid URL issue.
TransformationController
[Route("api/v1/transformation-controller/")]
TransformationController : ControllerBase
{
[HttpPost("workunits")]
public Task<Response> TransformWorkunits()
{
//logic
}
[HttpPost("documents")]
public Task<Response> TransformDocuments()
{
//logic
}
}
SynchronizationController
[Route("api/v1/synchronization-controller/")]
TransformationController : ControllerBase
{
[HttpPost("workunits")]
public Task<Response> SyncWorkunits()
{
//logic
}
}
So the URLs will be:
[POST] api/v1/transformation-controller/workunits
[POST] api/v1/synchronization-controller/workunits
[POST] api/v1/transformation-controller/documents
So this is a way to avoid verbs and fit REST rules.
If there will be more objects to transform/sync from and into, then you'll have to improve this approach.

REST - Updating partial data

I am currently programming a REST service and a website that mostly uses this REST service.
Model:
public class User {
private String realname;
private String username;
private String emailAddress;
private String password;
private Role role;
..
}
View:
One form to update
realname
email address
username
Another form to update the role
And a third form to change the password
.
Focussing on the first view, which pattern would be a good practice?
PUT /user/{userId}
imho not because the form contains only partial data (not role, not password). So it cannot send a whole user object.
PATCH /user/{userId}
may be ok. Is a good way to implement it like:
1) read current user entity
2)
if(source.getRealname() != null) // Check if field was set (partial update)
dest.setRealname(source.getRealname());
.. for all available fields
3) save dest
POST /user/{userId}/generalInformation
as summary for realname, email, username
.
Thank you!
One problem with this approach is that user cannot nullify optional fields since code is not applying the value if (input is empty and value) is null.
This might be ok for password or other required entity field but for example if you have an optional Note field then the user cannot "clean" the field.
Also, if you are using a plain FORM you cannot use PATCH method, only GET or POST.
If you are using Ajax you might be interested in JSON Merge Patch (easier) and/or JavaScript Object Notation (JSON) Patch (most complete); for an overview of the problems that one can find in partial updates and in using PATCH see also this page.
A point is that a form can only send empty or filled value, while a JSON object property can have three states: value (update), null (set null) and no-property (ignore).
An implementation I used with success is ZJSONPATCH
Focussing on the first view, which pattern would be a good practice?
My suggestion starts from a simple idea: how would you do this as web pages in HTML?
You probably start from a page that offers a view of the user, with hyperlinks like "Update profile", "Update role", "Change password". Clicking on update profile would load an html form, maybe with a bunch of default values already filled in. The operator would make changes, then submit the form, which would send a message to an endpoint that knows how to decode the message body and update the model.
The first two steps are "safe" -- the operator isn't proposing any changes. In the last step, the operator is proposing a change, so safe methods would not be appropriate.
HTML, as a hypermedia format, is limited to two methods (GET, POST), so we might see the browser do something like
GET /user/:id
GET /forms/updateGeneralInformation?:id
POST /updates/generalInformation/:id
There are lots of different spellings you can use, depending on how to prefer to organize your resources. The browser doesn't care, because it's just following links.
You have that same flexibility in your API. The first trick in the kit should always be "can I solve this with a new resource?".
Ian S Robinson observed: specialization and innovation depend on an open set. If you restrict yourself to a closed vocabulary of HTTP methods, then the open set you need to innovate needs to lie elsewhere: the RESTful approach is to use an open set of resources.
Update of a profile really does sound like an operation that should be idempotent, so you'd like to use PUT if you can. Is there anything wrong with:
GET /user/:id/generalInformation
PUT /user/:id/generalInformation
It's a write, it's idempotent, it's a complete replacement of the generalInformation resource, so the HTTP spec is happy.
Yes, changing the current representation of multiple resources with a single request is valid HTTP. In fact, this is one of the approaches described by RFC 7231
Partial content updates are possible by targeting a separately identified resource with state that overlaps a portion of the larger resource
If you don't like supporting multiple views of a resource and supporting PUT on each, you can apply the same heuristic ("add more resources") by introducing a command queue to handle changes to the underlying model.
GET /user/:id/generalInformation
PUT /changeRequests/:uuid
Up to you whether you want to represent all change requests as entries in the same collection, or having specialized collections of change requests for subsets of operations. Tomato, tomahto.

MVC 6 Attribute Routing using the new "[controller]/[action]" Tokens and Areas

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

Performing Explicit Route Mapping based upon Web Api v2 Attributes

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?

ASP.NET MVC2 AsyncController: Does performing multiple async operations in series cause a possible race condition?

The preamble
We're implementing a MVC2 site that needs to consume an external API via https (We cannot use WCF or even old-style SOAP WebServices, I'm afraid). We're using AsyncController wherever we need to communicate with the API, and everything is running fine so far.
Some scenarios have come up where we need to make multiple API calls in series, using results from one step to perform the next.
The general pattern (simplified for demonstration purposes) so far is as follows:
public class WhateverController : AsyncController
{
public void DoStuffAsync(DoStuffModel data)
{
AsyncManager.OutstandingOperations.Increment();
var apiUri = API.getCorrectServiceUri();
var req = new WebClient();
req.DownloadStringCompleted += (sender, e) =>
{
AsyncManager.Parameters["result"] = e.Result;
AsyncManager.OutstandingOperations.Decrement();
};
req.DownloadStringAsync(apiUri);
}
public ActionResult DoStuffCompleted(string result)
{
return View(result);
}
}
We have several Actions that need to perform API calls in parallel working just fine already; we just perform multiple requests, and ensure that we increment AsyncManager.OutstandingOperations correctly.
The scenario
To perform multiple API service requests in series, we presently are calling the next step within the event handler for the first request's DownloadStringCompleted. eg,
req.DownloadStringCompleted += (sender, e) =>
{
AsyncManager.Parameters["step1"] = e.Result;
OtherActionAsync(e.Result);
AsyncManager.OutstandingOperations.Decrement();
}
where OtherActionAsync is another action defined in this same controller following the same pattern as defined above.
The question
Can calling other async actions from within the event handler cause a possible race when accessing values within AsyncManager?
I tried looking around MSDN but all of the commentary about AsyncManager.Sync() was regarding the BeginMethod/EndMethod pattern with IAsyncCallback. In that scenario, the documentation warns about potential race conditions.
We don't need to actually call another action within the controller, if that is off-putting to you. The code to build another WebClient and call .DownloadStringAsync() on that could just as easily be placed within the event handler of the first request. I have just shown it like that here to make it slightly easier to read.
Hopefully that makes sense! If not, please leave a comment and I'll attempt to clarify anything you like.
Thanks!
It turns out the answer is "No".
(for future reference incase anyone comes across this question via a search)