diff --git a/back/src/Kyoo.Core/Controllers/Repositories/EpisodeRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/EpisodeRepository.cs
index 30e8a7a9..3820102c 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/EpisodeRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/EpisodeRepository.cs
@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Threading.Tasks;
 using Kyoo.Abstractions.Controllers;
@@ -79,22 +80,15 @@ public class EpisodeRepository(DatabaseContext database, IRepository<Show> shows
 	protected override async Task Validate(Episode resource)
 	{
 		await base.Validate(resource);
+		resource.Show = null;
 		if (resource.ShowId == Guid.Empty)
-		{
-			if (resource.Show == null)
-			{
-				throw new ArgumentException(
-					$"Can't store an episode not related "
-						+ $"to any show (showID: {resource.ShowId})."
-				);
-			}
-			resource.ShowId = resource.Show.Id;
-		}
+			throw new ValidationException("Missing show id");
+		resource.Season = null;
 		if (resource.SeasonId == null && resource.SeasonNumber != null)
 		{
-			resource.Season = await Database.Seasons.FirstOrDefaultAsync(x =>
+			resource.SeasonId = await Database.Seasons.Where(x =>
 				x.ShowId == resource.ShowId && x.SeasonNumber == resource.SeasonNumber
-			);
+			).Select(x => x.Id).FirstOrDefaultAsync();
 		}
 		await thumbnails.DownloadImages(resource);
 	}
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/GenericRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/GenericRepository.cs
index a862aabd..dbe199f2 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/GenericRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/GenericRepository.cs
@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -268,7 +269,7 @@ public abstract class GenericRepository<T>(DatabaseContext database) : IReposito
 	public virtual async Task<T> Create(T obj)
 	{
 		await Validate(obj);
-		Database.Entry(obj).State = EntityState.Added;
+		Database.Add(obj);
 		await Database.SaveChangesAsync(() => Get(obj.Slug));
 		await IRepository<T>.OnResourceCreated(obj);
 		return obj;
@@ -295,7 +296,7 @@ public abstract class GenericRepository<T>(DatabaseContext database) : IReposito
 	public virtual async Task<T> Edit(T edited)
 	{
 		await Validate(edited);
-		Database.Entry(edited).State = EntityState.Modified;
+		Database.Update(edited);
 		await Database.SaveChangesAsync();
 		await IRepository<T>.OnResourceEdited(edited);
 		return edited;
@@ -323,7 +324,7 @@ public abstract class GenericRepository<T>(DatabaseContext database) : IReposito
 		}
 	}
 
-	/// <exception cref="ArgumentException">
+	/// <exception cref="ValidationException">
 	/// You can throw this if the resource is illegal and should not be saved.
 	/// </exception>
 	protected virtual Task Validate(T resource)
@@ -334,9 +335,9 @@ public abstract class GenericRepository<T>(DatabaseContext database) : IReposito
 		)
 			return Task.CompletedTask;
 		if (string.IsNullOrEmpty(resource.Slug))
-			throw new ArgumentException("Resource can't have null as a slug.");
+			throw new ValidationException("Resource can't have null as a slug.");
 		if (resource.Slug == "random")
-			throw new ArgumentException("Resources slug can't be the literal \"random\".");
+			throw new ValidationException("Resources slug can't be the literal \"random\".");
 		return Task.CompletedTask;
 	}
 
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/LibraryItemRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/LibraryItemRepository.cs
index 9da7cc99..27d6e844 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/LibraryItemRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/LibraryItemRepository.cs
@@ -30,7 +30,8 @@ namespace Kyoo.Core.Controllers;
 /// <summary>
 /// A local repository to handle library items.
 /// </summary>
-public class LibraryItemRepository : DapperRepository<ILibraryItem>
+public class LibraryItemRepository(DbConnection database, SqlVariableContext context)
+	: DapperRepository<ILibraryItem>(database, context)
 {
 	// language=PostgreSQL
 	protected override FormattableString Sql =>
@@ -78,9 +79,6 @@ public class LibraryItemRepository : DapperRepository<ILibraryItem>
 		throw new InvalidDataException();
 	}
 
-	public LibraryItemRepository(DbConnection database, SqlVariableContext context)
-		: base(database, context) { }
-
 	public async Task<ICollection<ILibraryItem>> GetAllOfCollection(
 		Guid collectionId,
 		Filter<ILibraryItem>? filter = default,
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/MovieRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/MovieRepository.cs
index 4ab8b73a..c04a72cb 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/MovieRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/MovieRepository.cs
@@ -71,8 +71,8 @@ public class MovieRepository(
 		await base.Validate(resource);
 		if (resource.Studio != null)
 		{
-			resource.Studio = await studios.CreateIfNotExists(resource.Studio);
-			resource.StudioId = resource.Studio.Id;
+			resource.StudioId = (await studios.CreateIfNotExists(resource.Studio)).Id;
+			resource.Studio = null;
 		}
 		await thumbnails.DownloadImages(resource);
 	}
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/SeasonRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/SeasonRepository.cs
index 9d7b46bb..590d0b10 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/SeasonRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/SeasonRepository.cs
@@ -80,17 +80,9 @@ public class SeasonRepository(DatabaseContext database, IThumbnailsManager thumb
 	protected override async Task Validate(Season resource)
 	{
 		await base.Validate(resource);
+		resource.Show = null;
 		if (resource.ShowId == Guid.Empty)
-		{
-			if (resource.Show == null)
-			{
-				throw new ValidationException(
-					$"Can't store a season not related to any show "
-						+ $"(showID: {resource.ShowId})."
-				);
-			}
-			resource.ShowId = resource.Show.Id;
-		}
+			throw new ValidationException("Missing show id");
 		await thumbnails.DownloadImages(resource);
 	}
 }
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/ShowRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/ShowRepository.cs
index ed67e2df..17ee8251 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/ShowRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/ShowRepository.cs
@@ -60,7 +60,7 @@ public class ShowRepository(
 				&& existing.StartAir?.Year != obj.StartAir?.Year
 			)
 		{
-			obj.Slug = $"{obj.Slug}-{obj.StartAir!.Value.Year}";
+			obj.Slug = $"{obj.Slug}-{obj.AirDate!.Value.Year}";
 			return base.Create(obj);
 		}
 	}
@@ -71,8 +71,8 @@ public class ShowRepository(
 		await base.Validate(resource);
 		if (resource.Studio != null)
 		{
-			resource.Studio = await studios.CreateIfNotExists(resource.Studio);
-			resource.StudioId = resource.Studio.Id;
+			resource.StudioId = (await studios.CreateIfNotExists(resource.Studio)).Id;
+			resource.Studio = null;
 		}
 		await thumbnails.DownloadImages(resource);
 	}