limit to one playout per channel (#164)

ErsatzTV.Application/Playouts/Commands/CreatePlayoutHandler.cs

@@ -48,7 +48,7 @@ namespace ErsatzTV.Application.Playouts.Commands
         }
 
         private async Task<Validation<BaseError, Playout>> Validate(CreatePlayout request) =>
-            (await ChannelMustExist(request), await ProgramScheduleMustExist(request), ValidatePlayoutType(request))
+            (await ValidateChannel(request), await ProgramScheduleMustExist(request), ValidatePlayoutType(request))
             .Apply(
                 (channel, programSchedule, playoutType) => new Playout
                 {
@@ -57,10 +57,19 @@ namespace ErsatzTV.Application.Playouts.Commands
                     ProgramSchedulePlayoutType = playoutType
                 });
 
+        private Task<Validation<BaseError, Channel>> ValidateChannel(CreatePlayout createPlayout) =>
+            ChannelMustExist(createPlayout).BindT(ChannelMustNotHavePlayouts);
+
         private async Task<Validation<BaseError, Channel>> ChannelMustExist(CreatePlayout createPlayout) =>
             (await _channelRepository.Get(createPlayout.ChannelId))
             .ToValidation<BaseError>("Channel does not exist.");
 
+        private async Task<Validation<BaseError, Channel>> ChannelMustNotHavePlayouts(Channel channel) =>
+            Optional(await _channelRepository.CountPlayouts(channel.Id))
+            .Filter(count => count == 0)
+            .Map(_ => channel)
+            .ToValidation<BaseError>("Channel already has one playout.");
+
         private async Task<Validation<BaseError, ProgramSchedule>> ProgramScheduleMustExist(
             CreatePlayout createPlayout) =>
             (await _programScheduleRepository.GetWithPlayouts(createPlayout.ProgramScheduleId))

ErsatzTV.Core/Interfaces/Repositories/IChannelRepository.cs

@@ -14,5 +14,6 @@ namespace ErsatzTV.Core.Interfaces.Repositories
         Task<List<Channel>> GetAllForGuide();
         Task Update(Channel channel);
         Task Delete(int channelId);
+        Task<int> CountPlayouts(int channelId);
     }
 }

ErsatzTV.Infrastructure/Data/Repositories/ChannelRepository.cs

@@ -1,6 +1,8 @@
 using System.Collections.Generic;
+using System.Data;
 using System.Linq;
 using System.Threading.Tasks;
+using Dapper;
 using ErsatzTV.Core.Domain;
 using ErsatzTV.Core.Interfaces.Repositories;
 using LanguageExt;
@@ -12,8 +14,13 @@ namespace ErsatzTV.Infrastructure.Data.Repositories
     public class ChannelRepository : IChannelRepository
     {
         private readonly TvContext _dbContext;
+        private readonly IDbConnection _dbConnection;
 
-        public ChannelRepository(TvContext dbContext) => _dbContext = dbContext;
+        public ChannelRepository(TvContext dbContext, IDbConnection dbConnection)
+        {
+            _dbContext = dbContext;
+            _dbConnection = dbConnection;
+        }
 
         public async Task<Channel> Add(Channel channel)
         {
@@ -81,5 +88,10 @@ namespace ErsatzTV.Infrastructure.Data.Repositories
             _dbContext.Channels.Remove(channel);
             await _dbContext.SaveChangesAsync();
         }
+
+        public Task<int> CountPlayouts(int channelId) =>
+            _dbConnection.QuerySingleAsync<int>(
+                @"SELECT COUNT(*) FROM Playout WHERE ChannelId = @ChannelId",
+                new { ChannelId = channelId });
     }
 }

docs/user-guide/search.md

@@ -24,11 +24,11 @@ Note that the `title` field is searched by default if no other field is specifie
 
 ## Sample Searches
 
-### Christmas Movies
+### Christmas
 
 `plot:christmas`
 
-### Christmas Movies without Horror
+### Christmas without Horror
 
 `plot:christmas NOT genre:horror`