[英]Working with F# types in C#
I have a C# web api which I use to access an F# library. 我有一个C#Web API,可用于访问F#库。 I have created a DU of the types I want to return and use pattern matching to choose which is return back to the c# controller. 我创建了我想返回的类型的DU,并使用模式匹配来选择返回到c#控制器的类型。
In the C# controller how do I access the data of the type which is return from the function call to the F# library? 在C#控制器中,如何访问从函数调用返回到F#库的类型的数据?
C# Controller C#控制器
public HttpResponseMessage Post()
{
var _result = Authentication.GetAuthBehaviour();
//Access item1 of my tuple
var _HTTPStatusCode = (HttpStatusCode)_result.item1;
//Access item2 of my tuple
var _body = (HttpStatusCode)_result.item2;
return base.Request.CreateResponse(_HTTPStatusCode, _body);
}
F# Types F#类型
module Types =
[<JsonObject(MemberSerialization=MemberSerialization.OptOut)>]
[<CLIMutable>]
type ValidResponse = {
odata: string;
token: string;
}
[<JsonObject(MemberSerialization=MemberSerialization.OptOut)>]
[<CLIMutable>]
type ErrorResponse = {
code: string;
message: string;
url: string;
}
type AuthenticationResponse =
| Valid of int * ValidResponse
| Error of int * ErrorResponse
F# function F#功能
module Authentication =
open Newtonsoft.Json
let GetAuthBehaviour () =
let behaviour = GetBehaviour.Value.authentication
match behaviour.statusCode with
| 200 ->
let deserializedAuthenticationResponse = JsonConvert.DeserializeObject<Types.ValidResponse>(behaviour.body)
Types.Valid (behaviour.statusCode, deserializedAuthenticationResponse)
| _ ->
let deserializedAuthenticationResponse = JsonConvert.DeserializeObject<Types.ErrorResponse>(behaviour.body)
Types.Error (behaviour.statusCode, deserializedAuthenticationResponse)
F# Discriminated Unions are compiled as abstract classes, with each case being a derived nested class. F#区分联合被编译为抽象类,每种情况都是派生的嵌套类。 From C#, you can access the cases by attempting to downcast the result from GetAuthBehaviour
: 在C#中,您可以尝试通过下推GetAuthBehaviour
的结果来访问案例:
public HttpResponseMessage Post()
{
var result = Authentication.GetAuthBehaviour();
var valid = result as Types.AuthenticationResponse.Valid;
if (valid != null)
{
int statusCode = valid.Item1;
Types.ValidResponse body = valid.Item2;
return this.CreateResponse(statusCode, body);
}
var error = result as Types.AuthenticationResponse.Error;
if (error != null)
{
int statusCode = error.Item1;
Types.ErrorResponse body = error.Item2;
return this.CreateResponse(statusCode, body);
}
throw new InvalidOperationException("...");
}
Notice that the C# compiler doesn't know that you've handled all the cases, so you'll need to supply a branch that handles the case where result
is neither Valid
nor Error
. 注意,C#编译器不知道您已经处理了所有情况,因此您需要提供一个分支来处理result
既不是Valid
也不是Error
。 Here, I've simply thrown an exception as an example, but in a Web API, it'd probably be more appropriate to return a 500
status code. 在这里,我仅以抛出异常为例,但是在Web API中,返回500
状态代码可能更合适。
All that said, though, why even have the trouble of writing and maintaining the Controllers in C#? 尽管如此,为什么还要用C#编写和维护Controller? You can write an ASP.NET Web API purely in F# . 您可以仅使用F#编写ASP.NET Web API 。
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