Add custom relations on library items (first pass)

back/Kyoo.ruleset

@@ -2,6 +2,7 @@
 	<Rules AnalyzerId="StyleCop.Analyzers" RuleNamespace="StyleCop.CSharp.MaintainabilityRules">
 		<Rule Id="SA1413" Action="None" />        <!-- UseTrailingCommasInMultiLineInitializers -->
 		<Rule Id="SA1414" Action="None" />        <!-- UseTrailingCommasInMultiLineInitializers -->
+		<Rule Id="SA1114" Action="None" />        <!-- UseTrailingCommasInMultiLineInitializers -->
 	</Rules>
 	<Rules AnalyzerId="StyleCop.Analyzers" RuleNamespace="StyleCop.CSharp.OrderingRules">
 		<Rule Id="SA1201" Action="None" />        <!-- ElementsMustAppearInTheCorrectOrder -->

back/src/Kyoo.Abstractions/Models/Attributes/LoadableRelationAttribute.cs

@@ -31,6 +31,10 @@ namespace Kyoo.Abstractions.Models.Attributes
 		/// </summary>
 		public string? RelationID { get; }
 
+		public string? Sql { get; set; }
+
+		public string? On { get; set; }
+
 		/// <summary>
 		/// Create a new <see cref="LoadableRelationAttribute"/>.
 		/// </summary>

back/src/Kyoo.Abstractions/Models/Resources/Show.cs

@@ -152,7 +152,23 @@ namespace Kyoo.Abstractions.Models
 		/// The first episode of this show.
 		/// </summary>
 		[Projectable(UseMemberBody = nameof(_FirstEpisode), OnlyOnInclude = true)]
-		[LoadableRelation] public Episode? FirstEpisode { get; set; }
+		[LoadableRelation(
+			// language=PostgreSQL
+			Sql = """
+				select
+					fe.*
+				from (
+					select
+						e.*,
+						row_number() over (partition by e.show_id order by e.absolute_number, e.season_number, e.episode_number) as number
+					from
+						episodes as e) as fe
+				where
+					fe.number <= 1
+			""",
+			On = "show_id"
+		)]
+		public Episode? FirstEpisode { get; set; }
 
 		private Episode? _FirstEpisode => Episodes!
 			.OrderBy(x => x.AbsoluteNumber)

back/src/Kyoo.Abstractions/Models/Utils/Include.cs

@@ -17,7 +17,6 @@
 // along with Kyoo. If not, see <https://www.gnu.org/licenses/>.
 
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
@@ -47,32 +46,42 @@ public class Include<T>
 		if (string.IsNullOrEmpty(fields))
 			return new Include<T>();
 
+		Type[] types = typeof(T).GetCustomAttribute<OneOfAttribute>()?.Types ?? new[] { typeof(T) };
 		return new Include<T>
 		{
-			Metadatas = fields.Split(',').Select<string, Metadata>(key =>
+			Metadatas = fields.Split(',').SelectMany(key =>
 			{
-				Type[] types = typeof(T).GetCustomAttribute<OneOfAttribute>()?.Types ?? new[] { typeof(T) };
+				var relations = types
-				PropertyInfo? prop = types
+					.Select(x => x.GetProperty(key, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance)!)
-					.Select(x => x.GetProperty(key, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance))
+					.Select(prop => (prop, attr: prop?.GetCustomAttribute<LoadableRelationAttribute>()!))
-					.FirstOrDefault();
+					.Where(x => x.prop != null && x.attr != null)
-				LoadableRelationAttribute? attr = prop?.GetCustomAttribute<LoadableRelationAttribute>();
+					.ToList();
-				if (prop == null || attr == null)
+				if (!relations.Any())
 					throw new ValidationException($"No loadable relation with the name {key}.");
-				if (attr.RelationID != null)
+				return relations
-					return new SingleRelation(prop.Name, prop.PropertyType, attr.RelationID);
+					.Select(x =>
+					{
+						(PropertyInfo prop, LoadableRelationAttribute attr) = x;
 
-				// Multiples relations are disabled due to:
+						if (attr.RelationID != null)
-				//   - Cartesian Explosions perfs
+							return new SingleRelation(prop.Name, prop.PropertyType, attr.RelationID) as Metadata;
-				//   - Code complexity added.
+
-				// if (typeof(IEnumerable).IsAssignableFrom(prop.PropertyType) && prop.PropertyType != typeof(string))
+						// Multiples relations are disabled due to:
-				// {
+						//   - Cartesian Explosions perfs
-				// 	// The property is either a list or a an array.
+						//   - Code complexity added.
-				// 	return new MultipleRelation(
+						// if (typeof(IEnumerable).IsAssignableFrom(prop.PropertyType) && prop.PropertyType != typeof(string))
-				// 		prop.Name,
+						// {
-				// 		prop.PropertyType.GetElementType() ?? prop.PropertyType.GenericTypeArguments.First()
+						// 	// The property is either a list or a an array.
-				// 	);
+						// 	return new MultipleRelation(
-				// }
+						// 		prop.Name,
-				throw new NotImplementedException();
+						// 		prop.PropertyType.GetElementType() ?? prop.PropertyType.GenericTypeArguments.First()
+						// 	);
+						// }
+						if (attr.Sql != null && attr.On != null)
+							return new CustomRelation(prop.Name, prop.PropertyType, attr.Sql, attr.On, prop.DeclaringType!);
+						throw new NotImplementedException();
+					})
+					.Distinct();
 			}).ToArray()
 		};
 	}
@@ -80,4 +89,6 @@ public class Include<T>
 	public abstract record Metadata(string Name);
 
 	public record SingleRelation(string Name, Type type, string RelationIdName) : Metadata(Name);
+
+	public record CustomRelation(string Name, Type type, string Sql, string On, Type Declaring) : Metadata(Name);
 }

back/src/Kyoo.Core/Controllers/Repositories/LibraryItemRepository.cs

@@ -131,25 +131,36 @@ namespace Kyoo.Core.Controllers
 		) ProcessInclude<T>(Include<T> include, Dictionary<string, Type> config)
 			where T : class
 		{
+			int relation = 0;
 			Dictionary<string, Type> retConfig = new();
 			StringBuilder join = new();
 
 			foreach (Include<T>.Metadata metadata in include.Metadatas)
 			{
+				relation++;
 				switch (metadata)
 				{
 					case Include<T>.SingleRelation(var name, var type, var rid):
 						string tableName = type.GetCustomAttribute<TableAttribute>()?.Name ?? $"{type.Name.ToSnakeCase()}s";
-						retConfig.Add(tableName, type);
+						retConfig.Add($"r{relation}", type);
-						join.AppendLine($"left join {tableName} on {tableName}.id = {_Property(rid, config)}");
+						join.AppendLine($"left join {tableName} as r{relation} on r{relation}.id = {_Property(rid, config)}");
 						break;
+					case Include<T>.CustomRelation(var name, var type, var sql, var on, var declaring):
+						string owner = config.First(x => x.Value == declaring).Key;
+						retConfig.Add($"r{relation}", type);
+						join.AppendLine($"left join ({sql}) as r{relation} on r{relation}.{on} = {owner}.id");
+						break;
+					default:
+						throw new NotImplementedException();
 				}
 			}
 
 			T Map(T item, IEnumerable<object> relations)
 			{
-				foreach ((string name, object value) in include.Fields.Zip(relations))
+				foreach ((string name, object? value) in include.Fields.Zip(relations))
 				{
+					if (value == null)
+						continue;
 					PropertyInfo? prop = item.GetType().GetProperty(name);
 					if (prop != null)
 						prop.SetValue(item, value);