I am evaluating how to add hypermedia links to DTO responses. Although there is no standard, add List to the response DTOs seems to be the suggested approach.
Do you know of any example or reference of implementation using ServiceStack framework?
Adding List is ok for me, but my doubts are about where to put the logic of the following links (Within the service or a specialized class that holds the state machine?) and where to resolve the routes (A filter?)
Thanks.
[Update] From ServiceStack version v3.9.62 it is posible to access Routes configuration via EndpointHost.Config.Metadata.Routes.RestPath, so the solution provided by tgmdbm can be improved withouth the need of "IReturn + Routes attributes", just using Metadata.Routes information.
In fact all service metadata can be queried and used to cross-cutting concerns. Servicestack rocks.
The way I do this currently is I pass back a response dto which implements an interface
public interface IHaveLinks
{
[IgnoreDataMember]
IEnumerable<Link> Links { get; }
}
public class Link
{
public string Name { get; set; }
public IReturn Request { get; set; }
public string Method { get; set; }
}
Then I use a response filter to generate the urls and populate the response headers with the links.
this.ResponseFilters.Add((req, res, dto) =>
{
if (!(dto is IHaveLinks))
return;
var links = (dto as IHaveLinks).Links
if(links == null || !links.Any())
return;
var linksText = links
.Select(x => string.Format("<{0}>; rel={1}"), x.Request.ToUrl(x.Method), x.Name));
var linkHeader = string.Join(", ", linksText);
res.AddHeader("Link", linkHeader);
});
This seems the cleanest way. The Link object above effectively says "If you make this request with this method you will get back the named resource". The only HTTP thing that bleeds up to the BLL is Method. But you could get rid of that and only pass back GET urls. Or map it to some generalised "operation"?
As an example:
public class ExampleService : Service
{
public ExamplesResponse Get(ExamplesRequest request)
{
var page = request.Page;
var data = // get data;
return new ExamplesResponse
{
Examples = data,
Links = new []
{
new Link { Name = "next", Request = request.AddPage(1), Method = "GET" },
new Link { Name = "previous", Request = request.AddPage(-1), Method = "GET" },
}
}
}
}
[Route("/examples/{Page}")]
public class ExamplesRequest : IReturn<ExamplesResponse>
{
public int Page { get; set; }
// ...
}
(The AddPage method returns a clone of the request and sets the Page property appropriately.)
Hope that helps.
Related
It might be a noob question or an architectural misunderstanding, but I ask it anyhow because I am out of ideas and search terms: The goal is to implement a controller CountriesController() which is supposed to concatenate the (JSONish) results of two endpoints.
Assume I have two endpoints api/allowedCountriesToSell and api/allowedCountriesToBuy which are implemented as CountriesSellController() and CountriesBuyController() respectively. Both of them give back data as JSON which I want to merge and offer as a new endpoint. I am aware that this architecture is not ideal, but I am not allowed to do it architecturally different. Furthermore, I actually have to POST two different files to those endpoints - both existing controllers contain something like
[HttpPost]
public ActionResult FileUpload(HttpPostedFileBase file, string selectBox)
{ // ...
My new endpoint compiles all these two required parameters, let's call them myFileX, and mySelectBox. Here what I have have so far:
var myOtherContoller1 = new CountriesSellController();
var list1 = myOtherContoller1.FileUpload(myFile1,mySelectBox);
var myOtherContoller2 = new CountriesSellController();
var list2 = myOtherContoller1.FileUpload(myFile2,mySelectBox);
my result = list1.asEnumerable().Concat(list2.asEnumerable()); // Pseudocode. Here I am lost.
return Ok(result);
The problem is that both list1 and list2 are of type IHttpActionResult and I am not sure how to extract the data inside that. Ideally, result would be of type IEnumerable<UploadStatusDto> where I define the respective data transfer object as
namespace API.Models
{
public class UploadStatusDto
{
public int UploadId { get; set; } // contained in the response of both controllers
public string FileName { get; set; } // myFileX - parameter for calling the 2 existing controllers
public int UploadStatus { get; set; } // coming back within listX
public int Type { get; set; } // whether it is a buy or a sell, i.e. which controller I called
}
Any guidance is appreciated.
You need to do something line this.
var response = await myOtherContoller1.FileUpload(myFile2,mySelectBox).ExecuteAsync();
This will return HttpResponseMessage and you can get the content from it
You can get your content like this: Getting content/message from HttpResponseMessage.
My suggestion though, would be to extract the logic of your other controllers to a service class, and call both in this and the other two, the logic that is now in the original controllers.
I am working on an Azure Mobile Apps project. Where I have to define a Table Controller with that can accept two parameters and give a list of values. I have a DataObject for ProductItem, which is
public class ProductItem : EntityData
{
public string Name { get; set; }
public string Details { get; set; }
public double Price { get; set; }
public string Image { get; set; }
public Merchant Merchant { get; set; }
}
I need to get a specific Product item, filter by its Price and Merchant. Already in the ProductItemContoller, I have scaffolded
// GET tables/ProductItem
public IQueryable<ProductItem> GetAllProductItems()
{
return Query();
}
// GET tables/ProductItem/48D68C86-6EA6-4C25-AA33-223FC9A27959
public SingleResult<ProductItem> GetProductItem(string id)
{
return Lookup(id);
}
by looking at existing examples. But in examples, we have not called any of the given methods from Client. Rather, IEnumerable<ProductItem> items = await productTable.ToEnumerableAsync(); was called.
My question is why can't we call GetAllProductItems() which was already defined in the controller to the client. If we can call, how to do it.
And also, I need to have a controller method, I need to have a GetAllProductByMerchat(string merchantId). How can I make this possible.
The Table controllers are called automatically by the client SDKs on your behalf, allowing you to work with LINQ queries on the client. You can use something like:
var items = productTable.Where(p => p.Price < 100).ToListAsync();
This gets translated into an OData query across the wire, then translated back into a LINQ query on the server, where it then gets translated into SQL and executed on the SQL Azure instance.
For more information, see chapter 3 of http://aka.ms/zumobook
Did you mean this?
// Server method:
[HttpGet]
[Route("GetAllProductItems")]
public IQueryable<ProductItem> GetAllProductItems()
{
return Query();
}
// Client call
var result = await MobileService.InvokeApiAsync<IQueryable<ProductItem>>("ProductItem/GetAllProductItems", HttpMethod.Get, null);
Remember to add these attribute before the ProductItemController:
[MobileAppController]
[RoutePrefix("api/ProductItem")]
You can do the same thing to your GetAllProductByMerchat(string merchantId) method.
Unable to form a post request body. Please explain how pass list of items in post request body.
Here is my request body:
"serviceslist":[{"servicecentermapNbr":13,
"serviceQty":1},
{"servicecentermapNbr":15,
"serviceQty":1}]
I tried to solve it with lambda expression like below:
var services = items.Select(service => new { servicecentermapNbr = service.servicecentermapNbr, serviceQty =service.Quatity}).ToList();
But the request body formed like:
{System.Linq.Enumerable.WhereSelectListIterator<Data_Access.DataModal.ServiceList,<>f__AnonymousType0<int,int>>}
Instead of the list of items mentioned above.
Please explain me how to resolve it.
I don't know what that items object is in your case, but this is how scenario this would usually look:
[HttpPost]
public IHttpActionResult Create(List<ServiceModel> serviceModelList) {
//work involving model
}
public class ServiceModel
{
public int CenterMapNbr { get; set; }
public int Qty { get; set; }
}
<TL;DR>
At a minimum, I'm looking for a way to conditionally exclude certain properties on the resource from being included in the response on a per-call basis (See fields below).
Ideally, I'd like to implement a REST service with ServiceStack that supports all the major points below.
UPDATE
While I really like ServiceStack's approach in general and would prefer to use it if possible, if it isn't particularly well suited towards these ideas I'd rather not bend over backwards bastardizing it to make it work. If that's the case, can anyone point to another c# framework that might be more appropriate? I'm actively exploring other options myself, of course.
</TD;DR>
In this talk entitled Designing REST + JSON APIs, the presenter describes his strategy for Resource References (via href property on resources) in JSON. In addition to this, he describes two query parameters (fields and expand) for controlling what data is included the response of a call to a REST service. I've been trying without success to dig into the ServiceStack framework to achieve support for fields in particular but have thus far been unsuccessful. Is this currently possible in ServiceStack? Ideally the solution would be format agnostic and would therefore work across all of ServiceStack's supported output formats. I would imagine expand would follow the same strategy.
I'll describe these features here but I think the talk at the link does a better job of explaining them.
Lets say we have an Profiles resource with the following properties: givenName, surname, gender, and favColor. The Profiles resource also includes a list of social networks the user belongs to in the socialNetworks property.
href - (42:22 in video) Every resource includes a full link to it on the REST service. A call to GET /profiles/123 would return
{
"href":"https://host/profiles/123",
"givenName":"Bob",
"surname":"Smith",
"gender":"male",
"favColor":"red",
"socialNetworks": {
"href":"https://host/socialNetworkMemberships?profileId=123"
}
}
Notice that the socialNetworks property returns an object with just the href value populated. This keeps the response short and focused while also giving the end user enough information to make further requests if desired. The href property, used across the board in this manor, makes it easy (conceptually anyway) to reuse resource data structures as children of other resources.
fields - (55:44 in video) Query string parameter that instructs the server to only include the specified properties of the desired resource in the REST response.
A normal response from GET /profiles/123 would include all the properties of the resource as seen above. When the fields query param is included in the request, only the fields specified are returned. 'GET /propfiles/123?fields=surname,favColor' would return
{
"href":"https://host/profiles/123",
"surname":"Smith",
"favColor":"red"
}
expand - (45:53 in video) Query string parameter that instructs the server to flesh out the specified child resources in the result. Using our example, if you were to call GET /profiles/123?expand=socialNetworks you might receive something like
{
"href":"https://host/profiles/123",
"givenName":"Bob",
"surname":"Smith",
"gender":"male",
"favColor":"red",
"socialNetworks": {
"href":"https://host/socialNetworkMemberships?profileId=123",
"items": [
{
"href":"https://host/socialNetworkMemberships/abcde",
"siteName":"Facebook",
"profileUrl":"http://www.facebook.com/..."
},
...
]
}
}
So...in my opinion ServiceStack's best feature is that it makes sending, receiving and handling POCOs over HTTP super easy. How you set up the POCOs and what you do in between (within the 'Service') is up to you. Does SS have opinions? Yes. Do you have to agree with them? No. (But you probably should :))
I think expanding on something like below would get you close to how you want to handle your api. Probably not the best example of ServiceStack but the ServiceStack code/requirements are barely noticeable and don't get in your way (AppHost configure not shown). You could probably do something similar in other .NET Frameworks (MVC/Web API/etc) but, in my opinion, won't look as much like straight C#/.NET code as with ServiceStack.
Request classes
[Route("/Profiles/{Id}")]
public class Profiles
{
public int? Id { get; set; }
}
[Route("/SocialNetworks/{Id}")]
public class SocialNetworks
{
public int? Id { get; set; }
}
Base Response class
public class BaseResponse
{
protected virtual string hrefPath
{
get { return ""; }
}
public string Id { get; set; }
public string href { get { return hrefPath + Id; } }
}
Classes from example
public class Profile : BaseResponse
{
protected override string hrefPath { get { return "https://host/profiles/"; } }
public string GivenName { get; set; }
public string SurName { get; set; }
public string Gender { get; set; }
public string FavColor { get; set; }
public List<BaseResponse> SocialNetworks { get; set; }
}
public class SocialNetwork: BaseResponse
{
protected override string hrefPath { get { return "https://host/socialNetworkMemberships?profileId="; }}
public string SiteName { get; set; }
public string ProfileUrl { get; set; }
}
Services
public class ProfileService : Service
{
public object Get(Profiles request)
{
var testProfile = new Profile { Id= "123", GivenName = "Bob", SurName = "Smith", Gender = "Male", FavColor = "Red",
SocialNetworks = new List<BaseResponse>
{
new SocialNetwork { Id = "abcde", SiteName = "Facebook", ProfileUrl = "http://www.facebook.com/"}
}
};
if (!String.IsNullOrEmpty(this.Request.QueryString.Get("fields")) || !String.IsNullOrEmpty(this.Request.QueryString.Get("expand")))
return ServiceHelper.BuildResponseObject<Profile>(testProfile, this.Request.QueryString);
return testProfile;
}
}
public class SocialNetworkService : Service
{
public object Get(SocialNetworks request)
{
var testSocialNetwork = new SocialNetwork
{
Id = "abcde",
SiteName = "Facebook",
ProfileUrl = "http://www.facebook.com/"
};
if (!String.IsNullOrEmpty(this.Request.QueryString.Get("fields")) || !String.IsNullOrEmpty(this.Request.QueryString.Get("expand")))
return ServiceHelper.BuildResponseObject<SocialNetwork>(testSocialNetwork, this.Request.QueryString);
return testSocialNetwork;
}
}
Reflection Helper Class
public static class ServiceHelper
{
public static object BuildResponseObject<T>(T typedObject, NameValueCollection queryString) where T: BaseResponse
{
var newObject = new ExpandoObject() as IDictionary<string, object>;
newObject.Add("href", typedObject.href);
if (!String.IsNullOrEmpty(queryString.Get("fields")))
{
foreach (var propertyName in queryString.Get("fields").Split(',').ToList())
{
//could check for 'socialNetwork' and exclude if you wanted
newObject.Add(propertyName, typedObject.GetType().GetProperty(propertyName, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance).GetValue(typedObject, null));
}
}
if (!String.IsNullOrEmpty(queryString.Get("expand")))
{
foreach (var propertyName in queryString.Get("expand").Split(',').ToList())
{
newObject.Add(propertyName, typedObject.GetType().GetProperty(propertyName, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance).GetValue(typedObject, null));
}
}
return newObject;
}
}
Usually you can control the serialization of your DTOs by setting the DataMember attributes. With those attributes you can control if the property should have defaults or not.
Meaning if you simply do not define the property of the object you want to return, it should not be serialized and therefore will not be shown in the resulting Json.
ServiceStack internally uses the standard DataContract...Serializer, so this should be supported
Otherwise you could also make use of dynamic objects and simply compose your object at runtime, serialize it and send it back.
Here is a very very basic example:
var seri = JsonSerializer.Create(new JsonSerializerSettings() { });
using (var textWriter = new StringWriter())
{
var writer = new JsonTextWriter(textWriter);
dynamic item = new { Id = id };
seri.Serialize(writer, item);
return textWriter.ToString();
}
Environment is Visual Studio 2012, ServiceStack, ASP.NET Web Application Project (followed https://github.com/ServiceStack/ServiceStack/wiki/Create-your-first-webservice)
Looking through some of the classes in ServiceStack.Examples, I noticed that most of the services contain only one method. Either some override on Execute() or, if a REST service, some override of OnPost/Get/Put/Delete().
How should I approach making a full API set, if I have tens of functions I need implemented RegisterUser(), RemoveUser(), AddFriend(), RemoveFriend() ... One service per method?
public RegisterUserService : IService<User> { public object Execute(User> dto) { ... } }
public RemoveUserService : IService<User> { public object Execute(User> dto) { ... } }
public AddFriendService : IService<Friend> { public object Execute(Friend dto) { ... } }
public RemoveFriendService: IService<RequestDTO4> { public object Execute(Friend dto) { ... } }
I'm pretty lost on how to begin implementing a full API set. I've read the first and second wiki page on 'Creating your first webservice', which I've copied to make 1 service method. But now I want to make 10 or 40 service methods and I'm not sure how to do that.
I noticed that implementing from IRestService<T> allows you up to 4 methods instead of the one Execute() method, simply because each method corresponds to a different HTTP verb. So is there something like that I could write? Basically something like:
public MyService : IService/IRestService/ServiceBase?<User>
{
public object AddUser(User user) { }
public object RemoveUser(User user) { }
public object ModifyUser(User user) { }
}
Just looking for something that doesn't necessarily have to contain all methods in one service class, but as many as reasonably possible ... do I really have to create 1 service for each service method?
Note on pursuing a strictly RESTful architecture: I only read up a little on REST, but it seems like I'd have to strictly follow rules like: treat everything as a resource even if you have to re-design your models, no verbs in the URL names (/Friends, not /GetFriends because REST gives you OnGet(), OnPost(), OnPut(), and OnDelete() ... basically I'm interested in the easiest, quickest, and most painless way of implementing a a few dozen service methods. It's a personal project, so the requirements won't vary too much.
Thanks in advance for guiding me through this first step.
EDIT: Just saw this related question: How to send commands using ServiceStack?
Mythz said there's no "ServiceStack way" to design. The guy's question is pretty much like mine. I'm wondering how to stack a lot of service methods in a service.
EDIT 2: Just saw Need help on servicestack implementation, and Separate or combined ServiceStack services?.
I just tested the code below successfully with working routes:
[Route("/registerUser/setEmail/{Email}")]
[Route("/registerUser/setPassword/{Password}")]
[Route("/registerUser/setPhoneNumber/{PhoneNumber}")]
[Route("/lalal2395823")]
[Route("/test3234/test23423511")]
public class RegisterUser
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Nickname { get; set; }
public string PhoneNumber { get; set; }
public string Email { get; set; }
public string Password { get; set; }
}
But what I'd like is for each [Route("path")] to go to a different method, instead of having them all parsed in Execute() and having to parse which string isn't null or empty.
My Solution
I decided to take Rickard's advice and make a proper REST API, because it seems simpler and cleaner in the end.
This is now my class using the new ServiceStack API (new as of 9/24/12):
using UserModel = Project.Model.Entities.User;
[Route("/User", "POST")]
[Route("/User/{FirstName}", "POST")]
[Route("/User/{FirstName}/{LastName}", "POST")]
[Route("/User/{FirstName}/{LastName}/{Nickname}", "POST")]
[Route("/User/{FirstName}/{LastName}/{Nickname}/{PhoneNumber}", "POST")]
[Route("/User/{FirstName}/{LastName}/{Nickname}/{PhoneNumber}/{Email}", "POST")]
public class CreateUser : IReturn<UserModel>
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string Nickname { get; set; }
public string PhoneNumber { get; set; }
public string Email { get; set; }
public string Password { get; set; }
}
public class CreateUserService : Service
{
public object Post(CreateUser request)
{
try
{
using (var session = FluentNHibernateHelper.OpenSession())
{
using (var transaction = session.BeginTransaction())
{
var user = new UserModel()
{
FirstName = request.FirstName,
LastName = request.LastName,
Nickname = request.Nickname,
PhoneNumber = request.PhoneNumber,
Email = request.Email,
Password = request.Password,
};
session.SaveOrUpdate(user);
transaction.Commit();
return user;
}
}
}
catch
{
throw;
}
}
}
This is now a lot simpler with ServiceStack's new API Design released in (v3.9.15+).
#Rickard makes a lot of good points on how to re-structure your service so it's more REST-ful which is now easier to achieve with ServiceStack's new API which is now less restrictive and more flexible where the same service can handle multiple different Request DTOs and you're no longer restricted in the Response Type you can return.
Following the HTTP way you have to turn your way of thinking upside down. You need to think in terms of resources, i.e. users, friends, etc. Using HTTP you already have a finite set of methods, namely Get, Put, Post, and Delete.
Hence, the service API design could look like this:
RegisterUser() => POST /users
RemoveUser() => DELETE /users/{userid}
AddFriend() => POST /users/{userid}/friends
RemoveFriend() => DELETE /users/{userid}/friends/{friendid}
ModifyUser() => PUT /users/{userid}
etc.
To implement for example RemoveFriend in ServiceStack you could do like this:
public class UserFriendService : RestServiceBase<UserFriendRequest>
{
public override object OnPost(UserFriendRequest request)
{
// pseudo code
var user = GetUser(request.UserId);
var friend = GetUser(request.FriendId); // FriendId is a field in the HTTP body
user.Friends.Add(friend);
return HttpResult.Status201Created(user, ...);
}
//...
}
[Route("/users/{userId}/friends")]
public class UserFriendRequest
{
public string UserId { get; set; }
public string FriendId { get; set; }
}