add GetLink stuff (#19)

Application/AddLink/AddLinkCommand.cs

@@ -5,7 +5,7 @@ using MediatR;
 namespace HN.Application
 {
 
-  public class AddLinkCommand : IRequest<Guid>
+  public sealed class AddLinkCommand : IRequest<Guid>
   {
     [Required]
     [Url]

Application/GetLink/GetLinkQuery.cs

@@ -0,0 +1,17 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using MediatR;
+
+namespace HN.Application
+{
+  public sealed class GetLinkQuery : IRequest<LinkDTO>
+  {
+    [Required]
+    public Guid Id { get; set; }
+
+    public GetLinkQuery(Guid id)
+    {
+      Id = id;
+    }
+  }
+}

Application/GetLink/GetLinkQueryHandler.cs

@@ -0,0 +1,26 @@
+using System.Threading;
+using System.Linq;
+using System.Threading.Tasks;
+using MediatR;
+
+namespace HN.Application
+{
+  public sealed class GetLinkQueryHandler : IRequestHandler<GetLinkQuery, LinkDTO>
+  {
+    private readonly IDbContext _context;
+
+    public GetLinkQueryHandler(IDbContext context)
+    {
+      _context = context;
+    }
+
+    public Task<LinkDTO> Handle(GetLinkQuery request, CancellationToken cancellationToken)
+    {
+      var result = from link in _context.Links
+                   where link.Id == request.Id
+                   select new LinkDTO(link);
+
+      return Task.FromResult(result.FirstOrDefault());
+    }
+  }
+}

Application/ListLinks/LinkDTO.cs

@@ -1,4 +1,5 @@
 using System;
+using HN.Domain;
 
 namespace HN.Application
 {
@@ -7,5 +8,12 @@ namespace HN.Application
     public Guid Id { get; set; }
     public string Url { get; set; }
     public DateTime CreatedAt { get; set; }
+
+    public LinkDTO(Link link)
+    {
+      Id = link.Id;
+      Url = link.Url;
+      CreatedAt = link.CreatedAt;
+    }
   }
 }

Application/ListLinks/ListLinksQueryHandler.cs

@@ -17,12 +17,7 @@ namespace HN.Application
     public Task<LinkDTO[]> Handle(ListLinksQuery request, CancellationToken cancellationToken)
     {
       var links = from link in _context.Links
-                  select new LinkDTO
-                  {
-                    Id = link.Id,
-                    Url = link.Url,
-                    CreatedAt = link.CreatedAt
-                  };
+                  select new LinkDTO(link);
 
       return Task.FromResult(links.ToArray());
     }

Apps/Website/Controllers/LinksController.cs

@@ -2,6 +2,7 @@ using Microsoft.AspNetCore.Mvc;
 using HN.Application;
 using MediatR;
 using System.Threading.Tasks;
+using System;
 
 namespace Website.Controllers
 {
@@ -14,11 +15,18 @@ namespace Website.Controllers
       _bus = bus;
     }
 
+    [HttpGet]
     public async Task<IActionResult> Index()
     {
       return View(await _bus.Send(new ListLinksQuery()));
     }
 
+    [HttpGet("{controller}/{id}")]
+    public async Task<IActionResult> Show(Guid id)
+    {
+      return View(await _bus.Send(new GetLinkQuery(id)));
+    }
+
     public IActionResult Create()
     {
       return View(new AddLinkCommand());

Apps/Website/Views/Links/Show.cshtml

@@ -0,0 +1,3 @@
+@model HN.Application.LinkDTO
+
+<partial name="_LinkItem" model="@Model" />

Domain/Link.cs

@@ -2,7 +2,7 @@
 
 namespace HN.Domain
 {
-    public class Link
+  public sealed class Link
   {
     public Guid Id { get; }
     public string Url { get; }