Adds QueryProcessor to separate queries from Controllers

KillTeam/Controllers/TeamsController.cs

@@ -5,7 +5,8 @@
 using System.Windows.Input;
 using KillTeam.Commands;
 using KillTeam.Commands.Handlers;
-
+using KillTeam.Queries;
+using KillTeam.Queries.Handlers;
 using KillTeam.Services;
 using KillTeam.ViewModels;
 using Microsoft.EntityFrameworkCore;
@@ -23,9 +24,11 @@ public class TeamsController
         public ICommand OpenTeam { get; private set; }
         public ICommand DeleteTeam { get; private set; }
 
-        public TeamsController(IList<ToolbarItem> toolbarItems,
+        public TeamsController(
+            IList<ToolbarItem> toolbarItems,
             IHandleCommands<DeleteTeamCommand> deleteTeamCommandHandler,
-            IHandleCommands<ReorderTeamsCommand> reorderTeamsCommandHandler)
+            IHandleCommands<ReorderTeamsCommand> reorderTeamsCommandHandler,
+            IQueryProcessor queryProcessor)
         {
             Items = new ObservableCollection<TeamsViewModel>();
 
@@ -34,6 +37,7 @@ public TeamsController(IList<ToolbarItem> toolbarItems,
 
             _reorderTeamsCommandHandler = reorderTeamsCommandHandler;
             _deleteTeamCommandHandler = deleteTeamCommandHandler;
+            _queryProcessor = queryProcessor;
         }
 
         public async Task Refresh()
@@ -76,13 +80,10 @@ private void InitializeCommands()
         private async Task UpdateItems()
         {
             Items.Clear();
-            var teams = await KTContext.Db.Teams
-                                    .Include(e => e.Faction)
-                                    .Include(e => e.Members)
-                                    .AsNoTracking()
-                                    .OrderBy(post => post.Position)
-                                    .ToListAsync();
-            teams.ForEach(i => Items.Add(new TeamsViewModel(i.Id, i.Name, i.Cost, i.FactionNameAndMembersCount)));
+
+            var teams = await _queryProcessor.Execute<AllTeamsQuery, List<TeamsViewModel>>(new AllTeamsQuery());
+
+            teams.ForEach(t => Items.Add(t));
         }
 
         private void AddTeamExecuted()
@@ -124,5 +125,6 @@ private async Task VersionExecuted()
 
         private readonly IHandleCommands<ReorderTeamsCommand> _reorderTeamsCommandHandler;
         private readonly IHandleCommands<DeleteTeamCommand> _deleteTeamCommandHandler;
+        private readonly IQueryProcessor _queryProcessor;
     }
 }

KillTeam/Models/Team.cs

@@ -179,16 +179,6 @@ public List<string> Errors
                 return liste;
             }
         }
-
-        [JsonIgnore]
-        public string FactionNameAndMembersCount
-        {
-            get
-            {
-                int count = GetSelectedMembers().Count();
-                return Faction.Name + " - " + count + " " + (count <= 1 ? Properties.Resources.Membre : Properties.Resources.Membres);
-            }
-        }
 
         #endregion Calculated Properties
 

KillTeam/Queries/AllTeamsQuery.cs

@@ -0,0 +1,7 @@
+namespace KillTeam.Queries
+{
+    public class AllTeamsQuery : IQuery
+    {
+
+    }
+}

KillTeam/Queries/Handlers/AllTeamsQueryHandler.cs

@@ -0,0 +1,42 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using KillTeam.Services;
+using KillTeam.ViewModels;
+using Microsoft.EntityFrameworkCore;
+
+namespace KillTeam.Queries.Handlers
+{
+    public class AllTeamsQueryHandler : IQueryHandler<AllTeamsQuery, List<TeamsViewModel>>
+    {
+        public async Task<List<TeamsViewModel>> Execute(AllTeamsQuery query)
+        {
+            var teams = await KTContext.Db.Teams
+                .Include(e => e.Faction)
+                .Include(e => e.Members)
+                .AsNoTracking()
+                .OrderBy(post => post.Position)
+                .Select(t => new
+                {
+                    t.Id,
+                    t.Name,
+                    t.Members,
+                    t.Faction,
+                    t.Roster
+                })
+                .ToListAsync();
+
+            return teams
+                .Select(t =>
+                {
+                    var selectedMembers = t.Members.Where(m => m.Selected || !t.Roster).ToList();
+                    var count = selectedMembers.Count();
+                    var cost = selectedMembers.Sum(m => m.Cost);
+                    var subtitle = $"{t.Faction.Name} - {count} {(count <= 1 ? Properties.Resources.Membre : Properties.Resources.Membres)}";
+
+                    return new TeamsViewModel(t.Id, t.Name, cost, subtitle);
+                })
+                .ToList();
+        }
+    }
+}

KillTeam/Queries/Handlers/IQueryHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace KillTeam.Queries.Handlers
+{
+    public interface IQueryHandler<in TQuery, TResponse> where TQuery : IQuery
+    {
+        Task<TResponse> Execute(TQuery query);
+    }
+}

KillTeam/Queries/Handlers/IQueryProcessor.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace KillTeam.Queries.Handlers
+{
+    public interface IQueryProcessor
+    {
+        Task<TResult> Execute<TQuery, TResult>(TQuery query) where TQuery : IQuery;
+    }
+
+    public class QueryProcessor : IQueryProcessor
+    {
+        public static IQueryProcessor Instance() => _queryProcessor;
+
+        private static readonly IQueryProcessor _queryProcessor = new QueryProcessor();
+
+        public async Task<TResult> Execute<TQuery, TResult>(TQuery query) where TQuery : IQuery
+        {
+            var handlerType =
+                Assembly
+                    .GetAssembly(typeof(TQuery))
+                    .DefinedTypes
+                    .FirstOrDefault(t => t.ImplementedInterfaces.Contains(typeof(IQueryHandler<TQuery, TResult>)));
+
+            if (handlerType is null)
+                throw new InvalidOperationException($"No query handler for Query {typeof(TQuery)} for result {typeof(TResult)}");
+
+            var handler = Activator.CreateInstance(handlerType) as IQueryHandler<TQuery, TResult>;
+
+            return await handler.Execute(query);
+        }
+    }
+}

KillTeam/Queries/IQuery.cs

@@ -0,0 +1,7 @@
+namespace KillTeam.Queries
+{
+    public interface IQuery
+    {
+
+    }
+}

KillTeam/Views/TeamsView.xaml.cs

@@ -1,5 +1,6 @@
 using KillTeam.Commands.Handlers;
 using KillTeam.Controllers;
+using KillTeam.Queries.Handlers;
 using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
 using Xamarin.Forms.Xaml;
 
@@ -13,7 +14,11 @@ public TeamsView()
             InitializeComponent();
             On<Xamarin.Forms.PlatformConfiguration.iOS>().SetUseSafeArea(true);
 
-            BindingContext = new TeamsController(ToolbarItems, new DeleteTeamCommandHandler(), new ReorderTeamsCommandHandler());
+            BindingContext = new TeamsController(
+                ToolbarItems, 
+                new DeleteTeamCommandHandler(), 
+                new ReorderTeamsCommandHandler(),
+                QueryProcessor.Instance());
         }
 
         protected override async void OnAppearing()