Merge feature/gerbil-profilephoto (PROFILEPHOTO-BE): berechnetes profilePhotoUrl aufs Gerbil-DTO (Shared-Dep fuer Avatare, keine Migration, kein N+1)

GET /gerbils/{id}: loads first photo by sortOrder (2 queries, no N+1).
GET /gerbils list: batch-loads first photos for the page in one IN query.
profilePhotoUrl = /photos/files/{fileName} or null. No migration.
3 new tests: no-photo=null, sortOrder priority, list batch.

GerbilManager.Tests/GerbilProfilePhotoTests.cs

@@ -0,0 +1,83 @@
+using System.Net;
+using System.Net.Http.Json;
+using System.Text.Json;
+using System.Text.RegularExpressions;
+using GerbilManagerWebAPI.Models;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace GerbilManager.Tests;
+
+/// <summary>profilePhotoUrl: computed field on GerbilDto — first photo by sortOrder, or null.</summary>
+public class GerbilProfilePhotoTests : IClassFixture<ApiFactory>
+{
+    private readonly HttpClient _client;
+    private readonly ApiFactory _factory;
+
+    public GerbilProfilePhotoTests(ApiFactory factory)
+    {
+        _factory = factory;
+        _client = factory.CreateClient();
+    }
+
+    private static Guid ExtractId(string json) =>
+        Guid.Parse(Regex.Match(json, "\"id\":\"([^\"]+)\"").Groups[1].Value);
+
+    private static string? GetStr(JsonElement el, string prop) =>
+        el.TryGetProperty(prop, out var v) && v.ValueKind == JsonValueKind.String
+            ? v.GetString() : null;
+
+    private async Task<Guid> CreateGerbil(string name)
+    {
+        var resp = await _client.PostAsync("/gerbils", JsonContent.Create(new { name, gender = "female" }));
+        Assert.Equal(HttpStatusCode.Created, resp.StatusCode);
+        return ExtractId(await resp.Content.ReadAsStringAsync());
+    }
+
+    private void InsertPhotos(Guid gerbilId, params (string fileName, int sortOrder)[] photos)
+    {
+        using var scope = _factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<ApplicationContext>();
+        foreach (var (fn, so) in photos)
+            db.GerbilPhotos.Add(new GerbilPhoto
+            {
+                Id = Guid.NewGuid(), GerbilId = gerbilId,
+                FileName = fn, SortOrder = so, CreatedAt = DateTimeOffset.UtcNow,
+            });
+        db.SaveChanges();
+    }
+
+    [Fact]
+    public async Task GetById_without_photos_returns_null_profilePhotoUrl()
+    {
+        var id = await CreateGerbil("NoPhoto");
+        var json = await _client.GetStringAsync($"/gerbils/{id}");
+        var el = JsonDocument.Parse(json).RootElement;
+        Assert.True(el.TryGetProperty("profilePhotoUrl", out var v));
+        Assert.Equal(JsonValueKind.Null, v.ValueKind);
+    }
+
+    [Fact]
+    public async Task GetById_with_photos_returns_lowest_sortOrder_url()
+    {
+        var id = await CreateGerbil("PhotoGerbil");
+        InsertPhotos(id, ("second.jpg", 1), ("first.jpg", 0));
+
+        var json = await _client.GetStringAsync($"/gerbils/{id}");
+        var el = JsonDocument.Parse(json).RootElement;
+        Assert.Equal("/photos/files/first.jpg", GetStr(el, "profilePhotoUrl"));
+    }
+
+    [Fact]
+    public async Task GetList_returns_profilePhotoUrl_without_n_plus_1()
+    {
+        var id = await CreateGerbil("ListPhoto");
+        InsertPhotos(id, ("list-photo.jpg", 0));
+
+        var json = await _client.GetStringAsync("/gerbils");
+        var root = JsonDocument.Parse(json).RootElement;
+        var items = root.GetProperty("items").EnumerateArray().ToList();
+        var gerbil = items.FirstOrDefault(x => GetStr(x, "id") == id.ToString());
+        Assert.NotEqual(default, gerbil);
+        Assert.Equal("/photos/files/list-photo.jpg", GetStr(gerbil, "profilePhotoUrl"));
+    }
+}

GerbilManagerWebAPI/Dtos/ApiDtos.cs

@@ -29,7 +29,8 @@ namespace GerbilManagerWebAPI.Dtos
         List<string> CharacterTraits,
         string? CharacterNote,
         bool? IsDeaf,
-        bool IsResident);
+        bool IsResident,
+        string? ProfilePhotoUrl);
 
     public record LitterDto(
         Guid Id,

GerbilManagerWebAPI/Endpoints/GerbilEndpoints.cs

@@ -2,6 +2,7 @@ using GerbilManagerWebAPI.Common;
 using GerbilManagerWebAPI.Dtos;
 using GerbilManagerWebAPI.Models;
 using Gridify;
+using Gridify.EntityFramework;
 using Microsoft.AspNetCore.Http.HttpResults;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -16,8 +17,21 @@ namespace GerbilManagerWebAPI.Endpoints
 
             // GET /gerbils  (Gridify: filter/order/page; e.g. status==Active, litterId==…, orderBy=name)
             group.MapGet("/", async ([AsParameters] GridifyParams query, ApplicationContext db) =>
-                TypedResults.Ok(await db.Gerbils.AsNoTracking()
-                    .ToPagedResultAsync(query, ToDto)));
+            {
+                var q = query.ToQuery();
+                var paging = await db.Gerbils.AsNoTracking().GridifyAsync(q);
+                var ids = paging.Data.Select(g => g.Id).ToList();
+                var photoMap = ids.Count == 0 ? new Dictionary<Guid, string>() :
+                    await db.GerbilPhotos.AsNoTracking()
+                        .Where(p => ids.Contains(p.GerbilId))
+                        .GroupBy(p => p.GerbilId)
+                        .Select(g => new { GerbilId = g.Key, FileName = g.OrderBy(p => p.SortOrder).First().FileName })
+                        .ToDictionaryAsync(x => x.GerbilId, x => x.FileName);
+                var items = paging.Data
+                    .Select(g => ToDto(g, photoMap.TryGetValue(g.Id, out var fn) ? $"/photos/files/{fn}" : null))
+                    .ToList();
+                return TypedResults.Ok(new PagedResult<GerbilDto>(items, paging.Count, q.Page, q.PageSize));
+            });
 
             // GET /gerbils/breeders — distinct non-empty Herkunft values for the Tiere filter dropdown
             group.MapGet("/breeders", async (ApplicationContext db) =>
@@ -30,7 +44,14 @@ namespace GerbilManagerWebAPI.Endpoints
             group.MapGet("/{id:guid}", async Task<Results<Ok<GerbilDto>, NotFound>> (Guid id, ApplicationContext db) =>
             {
                 var g = await db.Gerbils.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id);
-                return g is null ? TypedResults.NotFound() : TypedResults.Ok(ToDto(g));
+                if (g is null) return TypedResults.NotFound();
+                var photoFileName = await db.GerbilPhotos.AsNoTracking()
+                    .Where(p => p.GerbilId == id)
+                    .OrderBy(p => p.SortOrder)
+                    .Select(p => p.FileName)
+                    .FirstOrDefaultAsync();
+                var profilePhotoUrl = photoFileName != null ? $"/photos/files/{photoFileName}" : null;
+                return TypedResults.Ok(ToDto(g, profilePhotoUrl));
             });
 
             // POST /gerbils
@@ -107,10 +128,10 @@ namespace GerbilManagerWebAPI.Endpoints
             g.IsResident = i.IsResident ?? (isCreate ? true : g.IsResident);
         }
 
-        internal static GerbilDto ToDto(Gerbil g) => new(
+        internal static GerbilDto ToDto(Gerbil g, string? profilePhotoUrl = null) => new(
             g.Id, g.Name, g.Gender, g.Status, g.LitterId, g.OriginContactId, g.ReceiverContactId,
             g.EnclosureId, g.ColorVarietyId, g.DateOfBirth, g.DateOfDeath, g.CauseOfDeath,
             g.GoHomeDate, g.Genotype, g.Notes, g.ImportSource, g.ExternalRef, g.OriginBreeder,
-            g.CharacterTraits, g.CharacterNote, g.IsDeaf, g.IsResident);
+            g.CharacterTraits, g.CharacterNote, g.IsDeaf, g.IsResident, profilePhotoUrl);
     }
 }