start working on commenting a link

Application/CommentLink/CommentLinkCommand.cs

@@ -0,0 +1,15 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using MediatR;
+
+namespace HN.Application
+{
+  public sealed class CommentLinkCommand : IRequest<Guid>
+  {
+    [Required]
+    public Guid LinkId { get; set; }
+
+    [Required]
+    public string Content { get; set; }
+  }
+}

Application/CommentLink/CommentLinkCommandHandler.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using HN.Domain;
+using MediatR;
+
+namespace HN.Application
+{
+  public sealed class CommentLinkCommandHandler : IRequestHandler<CommentLinkCommand, Guid>
+  {
+    private readonly ILinkRepository _linkRepository;
+    private readonly ICommentRepository _commentRepository;
+
+    public CommentLinkCommandHandler(ILinkRepository linkRepository, ICommentRepository commentRepository)
+    {
+      _linkRepository = linkRepository;
+      _commentRepository = commentRepository;
+    }
+
+    public async Task<Guid> Handle(CommentLinkCommand request, CancellationToken cancellationToken)
+    {
+      var link = await _linkRepository.GetByIdAsync(request.LinkId);
+      var comment = link.AddComment(request.Content);
+
+      await _commentRepository.AddAsync(comment);
+
+      return comment.Id;
+    }
+  }
+}

Apps/Website/Startup.cs

@@ -27,7 +27,8 @@ namespace Website
       services.AddDbContext<HNDbContext>(options => options.UseSqlite(Configuration.GetConnectionString("Default")));
       services.AddScoped<IDbContext, HNDbContext>();
       services.AddScoped<ILinkRepository, LinkRepository>();
-      services.AddMediatR(typeof(HN.Application.AddLinkCommand));
+      services.AddScoped<ICommentRepository, CommentRepository>();
+      services.AddMediatR(typeof(HN.Application.IDbContext));
 
       services.Configure<RouteOptions>(options =>
       {

Domain/Comment.cs

@@ -0,0 +1,20 @@
+using System;
+
+namespace HN.Domain
+{
+  public sealed class Comment
+  {
+    public Guid Id { get; private set; }
+    public Guid LinkId { get; private set; }
+    public string Content { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    internal Comment(Guid linkId, string content)
+    {
+      Id = Guid.NewGuid();
+      LinkId = linkId;
+      Content = content;
+      CreatedAt = DateTime.UtcNow;
+    }
+  }
+}

Domain/ICommentRepository.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace HN.Domain
+{
+  public interface ICommentRepository
+  {
+    Task AddAsync(Comment comment);
+  }
+}

Domain/Link.cs

@@ -33,5 +33,10 @@ namespace HN.Domain
     {
       _votes.Add(new Vote(VoteType.Down));
     }
+
+    public Comment AddComment(string content)
+    {
+      return new Comment(Id, content);
+    }
   }
 }

Infrastructure/CommentRepository.cs

@@ -0,0 +1,17 @@
+using System.Threading.Tasks;
+using HN.Domain;
+
+namespace HN.Infrastructure
+{
+  public sealed class CommentRepository : Repository<Comment>, ICommentRepository
+  {
+    public CommentRepository(HNDbContext context) : base(context)
+    {
+    }
+
+    public Task AddAsync(Comment comment)
+    {
+      return base.AddAsync(comment);
+    }
+  }
+}

Infrastructure/EntityTypes/CommentEntityType.cs

@@ -0,0 +1,22 @@
+using HN.Domain;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace HN.Infrastructure
+{
+  public sealed class CommentEntityType : IEntityTypeConfiguration<Comment>
+  {
+    public void Configure(EntityTypeBuilder<Comment> builder)
+    {
+      builder.ToTable("comments");
+      builder.HasKey(o => o.Id);
+      builder.HasOne<Link>()
+        .WithMany()
+        .HasForeignKey(o => o.LinkId)
+        .IsRequired();
+      builder.Property(o => o.Content).IsRequired();
+      builder.Property(o => o.CreatedAt).IsRequired();
+    }
+  }
+
+}

Infrastructure/LinkRepository.cs

@@ -11,19 +11,19 @@ namespace HN.Infrastructure
     {
     }
 
-    public async Task AddAsync(Link link)
+    public Task AddAsync(Link link)
     {
-      await base.AddAsync(link);
+      return base.AddAsync(link);
     }
 
     public Task<Link> GetByIdAsync(Guid id)
     {
-      return Entries.SingleOrDefaultAsync(o => o.Id == id);
+      return Entries.Include(l => l.Votes).SingleOrDefaultAsync(o => o.Id == id);
     }
 
-    public async Task UpdateAsync(Link link)
+    public Task UpdateAsync(Link link)
     {
-      await base.UpdateAsync(link);
+      return base.UpdateAsync(link);
     }
   }
 }

Infrastructure/Migrations/20201210171100_CreateComment.Designer.cs

@@ -0,0 +1,107 @@
+// <auto-generated />
+using System;
+using HN.Infrastructure;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+namespace Infrastructure.Migrations
+{
+    [DbContext(typeof(HNDbContext))]
+    [Migration("20201210171100_CreateComment")]
+    partial class CreateComment
+    {
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "5.0.0");
+
+            modelBuilder.Entity("HN.Domain.Comment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Content")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("LinkId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LinkId");
+
+                    b.ToTable("comments");
+                });
+
+            modelBuilder.Entity("HN.Domain.Link", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Url")
+                        .IsRequired()
+                        .HasMaxLength(500)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Url")
+                        .IsUnique();
+
+                    b.ToTable("links");
+                });
+
+            modelBuilder.Entity("HN.Domain.Vote", b =>
+                {
+                    b.Property<Guid>("LinkId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("Type")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("LinkId");
+
+                    b.ToTable("link_votes");
+                });
+
+            modelBuilder.Entity("HN.Domain.Comment", b =>
+                {
+                    b.HasOne("HN.Domain.Link", null)
+                        .WithMany()
+                        .HasForeignKey("LinkId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("HN.Domain.Vote", b =>
+                {
+                    b.HasOne("HN.Domain.Link", null)
+                        .WithMany("Votes")
+                        .HasForeignKey("LinkId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
+            modelBuilder.Entity("HN.Domain.Link", b =>
+                {
+                    b.Navigation("Votes");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Infrastructure/Migrations/20201210171100_CreateComment.cs

@@ -0,0 +1,42 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace Infrastructure.Migrations
+{
+    public partial class CreateComment : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "comments",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    LinkId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    Content = table.Column<string>(type: "TEXT", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "TEXT", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_comments", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_comments_links_LinkId",
+                        column: x => x.LinkId,
+                        principalTable: "links",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_comments_LinkId",
+                table: "comments",
+                column: "LinkId");
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "comments");
+        }
+    }
+}

Infrastructure/Migrations/HNDbContextModelSnapshot.cs

@@ -16,6 +16,29 @@ namespace Infrastructure.Migrations
             modelBuilder
                 .HasAnnotation("ProductVersion", "5.0.0");
 
+            modelBuilder.Entity("HN.Domain.Comment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Content")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("LinkId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LinkId");
+
+                    b.ToTable("comments");
+                });
+
             modelBuilder.Entity("HN.Domain.Link", b =>
                 {
                     b.Property<Guid>("Id")
@@ -54,6 +77,15 @@ namespace Infrastructure.Migrations
                     b.ToTable("link_votes");
                 });
 
+            modelBuilder.Entity("HN.Domain.Comment", b =>
+                {
+                    b.HasOne("HN.Domain.Link", null)
+                        .WithMany()
+                        .HasForeignKey("LinkId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
             modelBuilder.Entity("HN.Domain.Vote", b =>
                 {
                     b.HasOne("HN.Domain.Link", null)