Update collections to only refer to the root collection as /root

src/IIIFPresentation/API.Tests/Integration/GetCollectionTests.cs

@@ -140,7 +140,7 @@ public async Task Get_RootFlat_ReturnsEntryPointFlat_WhenAuthAndHeader()
 
         // Assert
         response.StatusCode.Should().Be(HttpStatusCode.OK);
-        collection!.Id.Should().Be("http://localhost/1/collections/RootStorage");
+        collection!.Id.Should().Be("http://localhost/1/collections/root");
         collection.PublicId.Should().Be("http://localhost/1");
         collection.Items!.Count.Should().Be(2);
         collection.Items[0].Id.Should().Be("http://localhost/1/collections/FirstChildCollection");
@@ -162,13 +162,14 @@ public async Task Get_RootFlat_ReturnsEntryPointFlat_WhenCalledById()
 
         // Assert
         response.StatusCode.Should().Be(HttpStatusCode.OK);
-        collection!.Id.Should().Be("http://localhost/1/collections/RootStorage");
+        collection!.Id.Should().Be("http://localhost/1/collections/root");
         collection.PublicId.Should().Be("http://localhost/1");
         collection.Items!.Count.Should().Be(2);
         collection.Items[0].Id.Should().Be("http://localhost/1/collections/FirstChildCollection");
         collection.TotalItems.Should().Be(2);
         collection.CreatedBy.Should().Be("admin");
         collection.Behavior.Should().Contain("public-iiif");
+        collection.Parent.Should().BeNull();
     }
 
     [Fact]
@@ -192,6 +193,7 @@ public async Task Get_ChildFlat_ReturnsEntryPointFlat_WhenCalledByChildId()
         collection.TotalItems.Should().Be(1);
         collection.CreatedBy.Should().Be("admin");
         collection.Behavior.Should().Contain("public-iiif");
+        collection.Parent.Should().Be("http://localhost/1/collections/root");
     }
 
     [Fact]
@@ -214,6 +216,7 @@ public async Task Get_PrivateChild_ReturnsCorrectlyFlatAndHierarchical()
         flatCollection.CreatedBy.Should().Be("admin");
         flatCollection.Behavior.Should().Contain("storage-collection");
         flatCollection.Behavior.Should().NotContain("public-iiif");
+        flatCollection.Parent.Should().Be("http://localhost/1/collections/root");
         hierarchicalResponse.StatusCode.Should().Be(HttpStatusCode.NotFound);
     }
 
@@ -238,7 +241,7 @@ public async Task Get_RootFlat_ReturnsItems_WhenCalledWithPageSize()
     }
 
     [Fact]
-    public async Task Get_RootFlat_ReturnsReducedItems_WhenCalledWithSmallPageSize()
+    public async Task Get_ChildFlat_ReturnsReducedItems_WhenCalledWithSmallPageSize()
     {
         // Arrange
         var requestMessage =
@@ -323,7 +326,7 @@ public async Task Get_RootFlat_ReturnsMaxPageSize_WhenCalledPageSizeExceedsMax()
     [InlineData("id")]
     [InlineData("slug")]
     [InlineData("created")]
-    public async Task Get_RootFlat_ReturnsCorrectItem_WhenCalledWithSmallPageSizeAndOrderBy(string field)
+    public async Task Get_ChildFlat_ReturnsCorrectItem_WhenCalledWithSmallPageSizeAndOrderBy(string field)
     {
         // Arrange
         var requestMessage =
@@ -363,15 +366,15 @@ public async Task Get_RootFlat_ReturnsFirstPageWithSecondItem_WhenCalledWithSmal
         // Assert
         collection.TotalItems.Should().Be(2);
         collection.View!.PageSize.Should().Be(1);
-        collection.View.Id.Should().Be($"http://localhost/1/collections/RootStorage?page=1&pageSize=1&orderByDescending={field}");
+        collection.View.Id.Should().Be($"http://localhost/1/collections/root?page=1&pageSize=1&orderByDescending={field}");
         collection.View.Page.Should().Be(1);
         collection.View.TotalPages.Should().Be(2);
         collection.Items!.Count.Should().Be(1);
         collection.Items[0].Id.Should().Be("http://localhost/1/collections/NonPublic");
     }
 
     [Fact]
-    public async Task Get_RootFlat_IgnoresOrderBy_WhenCalledWithInvalidOrderBy()
+    public async Task Get_ChildFlat_IgnoresOrderBy_WhenCalledWithInvalidOrderBy()
     {
         // Arrange
         var requestMessage =
@@ -386,7 +389,7 @@ public async Task Get_RootFlat_IgnoresOrderBy_WhenCalledWithInvalidOrderBy()
         // Assert
         collection.TotalItems.Should().Be(2);
         collection.View!.PageSize.Should().Be(1);
-        collection.View.Id.Should().Be($"http://localhost/1/collections/RootStorage?page=1&pageSize=1");
+        collection.View.Id.Should().Be($"http://localhost/1/collections/root?page=1&pageSize=1");
         collection.View.Page.Should().Be(1);
         collection.View.TotalPages.Should().Be(2);
         collection.Items!.Count.Should().Be(1);

src/IIIFPresentation/API.Tests/Integration/ModifyCollectionTests.cs

@@ -79,6 +79,9 @@ public async Task CreateCollection_CreatesCollection_WhenAllValuesProvided()
         fromDatabase.Tags.Should().Be("some, tags");
         fromDatabase.IsPublic.Should().BeTrue();
         fromDatabase.IsStorageCollection.Should().BeTrue();
+        responseCollection!.View!.PageSize.Should().Be(20);
+        responseCollection.View.Page.Should().Be(1);
+        responseCollection.View.Id.Should().Contain("?page=1&pageSize=20");
     }
 
     [Fact]
@@ -283,6 +286,9 @@ public async Task UpdateCollection_UpdatesCollection_WhenAllValuesProvided()
         fromDatabase.Tags.Should().Be("some, tags, 2");
         fromDatabase.IsPublic.Should().BeTrue();
         fromDatabase.IsStorageCollection.Should().BeTrue();
+        responseCollection!.View!.PageSize.Should().Be(20);
+        responseCollection.View.Page.Should().Be(1);
+        responseCollection.View.Id.Should().Contain("?page=1&pageSize=20");
     }
 
     [Fact]

src/IIIFPresentation/API/Converters/CollectionConverter.cs

@@ -113,14 +113,14 @@
     {
         var view = new View()
         {
             Id = dbAsset.GenerateFlatCollectionViewId(urlRoots, currentPage, pageSize, orderQueryParam),
             Type = PresentationType.PartialCollectionView,
             Page = currentPage,
             PageSize = pageSize,
             TotalPages = totalPages,
         };
 
-        if (totalPages > 1)
+        if (currentPage > 1)
         {
             view.First = dbAsset.GenerateFlatCollectionViewFirst(urlRoots, pageSize, orderQueryParam);
             view.Previous = dbAsset.GenerateFlatCollectionViewPrevious(urlRoots, currentPage, pageSize, orderQueryParam);

src/IIIFPresentation/API/Features/Storage/Helpers/PresentationContextX.cs

@@ -2,6 +2,7 @@
 using Core;
 using Microsoft.EntityFrameworkCore;
 using Models.API.Collection;
+using Models.Database.Collections;
 using Repository;
 using Repository.Helpers;
 
@@ -35,4 +36,24 @@ public static class PresentationContextX
 
         return null;
     }
+
+    public static async Task<Collection?> RetrieveCollection(this PresentationContext dbContext,  int customerId, string collectionId,
+        string rootCollectionId, CancellationToken cancellationToken)
+    {
+        Collection? collection;
+        if (collectionId.Equals(rootCollectionId, StringComparison.OrdinalIgnoreCase))
+        {
+            collection = await dbContext.Collections.AsNoTracking().FirstOrDefaultAsync(
+                s => s.CustomerId == customerId && s.Parent == null,
+                cancellationToken);
+        }
+        else
+        {
+            collection = await dbContext.Collections.AsNoTracking().FirstOrDefaultAsync(
+                s => s.CustomerId == customerId && s.Id == collectionId,
+                cancellationToken);
+        }
+
+        return collection;
+    }
 }

src/IIIFPresentation/API/Features/Storage/Helpers/RootCollection.cs

@@ -0,0 +1,6 @@
+namespace API.Features.Storage.Helpers;
+
+public static class RootCollection
+{
+    public const string Id = "root";
+}

src/IIIFPresentation/API/Features/Storage/Requests/CreateCollection.cs

@@ -1,6 +1,7 @@
 using API.Auth;
 using API.Converters;
 using API.Features.Storage.Helpers;
+using API.Helpers;
 using API.Infrastructure.Requests;
 using API.Settings;
 using Core;
@@ -33,8 +34,20 @@ public class CreateCollectionHandler(
 {
     private readonly ApiSettings settings = options.Value;
 
+    private const int CurrentPage = 1;
+
     public async Task<ModifyEntityResult<FlatCollection>> Handle(CreateCollection request, CancellationToken cancellationToken)
     {
+        // check parent exists
+        var parentCollection = await dbContext.RetrieveCollection(request.CustomerId,
+            request.Collection.Parent.GetLastPathElement(), RootCollection.Id, cancellationToken);
+
+        if (parentCollection == null)
+        {
+            return ModifyEntityResult<FlatCollection>.Failure(
+                $"The parent collection could not be found", WriteResult.Conflict);
+        }
+
         var collection = new Collection()
         {
             Id = Guid.NewGuid().ToString(),
@@ -45,7 +58,7 @@ public async Task<ModifyEntityResult<FlatCollection>> Handle(CreateCollection re
             IsPublic = request.Collection.Behavior.IsPublic(),
             IsStorageCollection = request.Collection.Behavior.IsStorageCollection(),
             Label = request.Collection.Label,
-            Parent = request.Collection.Parent!.GetLastPathElement(),
+            Parent = parentCollection.Id,
             Slug = request.Collection.Slug,
             Thumbnail = request.Collection.Thumbnail,
             Tags = request.Collection.Tags,
@@ -66,8 +79,10 @@ public async Task<ModifyEntityResult<FlatCollection>> Handle(CreateCollection re
             collection.FullPath = CollectionRetrieval.RetrieveFullPathForCollection(collection, dbContext);
         }
 
+        collection.UpdateParentForRootIfRequired(request.Collection.Parent);
+
         return ModifyEntityResult<FlatCollection>.Success(
-            collection.ToFlatCollection(request.UrlRoots, 1, settings.PageSize, 0, []), // there can be no items attached to this, as it's just been created
+            collection.ToFlatCollection(request.UrlRoots, settings.PageSize, CurrentPage, 0, []), // there can be no items attached to this, as it's just been created
             WriteResult.Created);
     }
 }

src/IIIFPresentation/API/Features/Storage/Requests/GetCollection.cs

@@ -1,4 +1,5 @@
-using API.Features.Storage.Models;
+using API.Features.Storage.Helpers;
+using API.Features.Storage.Models;
 using API.Helpers;
 using MediatR;
 using Microsoft.EntityFrameworkCore;
@@ -28,25 +29,11 @@ public class GetCollection(
 
 public class GetCollectionHandler(PresentationContext dbContext) : IRequestHandler<GetCollection, CollectionWithItems>
 {
-    private const string RootCollection = "root";
-
     public async Task<CollectionWithItems> Handle(GetCollection request,
         CancellationToken cancellationToken)
     {
-        Collection? collection;
-
-        if (request.Id.Equals(RootCollection, StringComparison.OrdinalIgnoreCase))
-        {
-            collection = await dbContext.Collections.AsNoTracking().FirstOrDefaultAsync(
-                s => s.CustomerId == request.CustomerId && s.Parent == null,
-                cancellationToken);
-        }
-        else
-        {
-            collection = await dbContext.Collections.AsNoTracking().FirstOrDefaultAsync(
-                s => s.CustomerId == request.CustomerId && s.Id == request.Id,
-                cancellationToken);
-        }
+        Collection? collection = await dbContext.RetrieveCollection(request.CustomerId, request.Id, RootCollection.Id, 
+            cancellationToken);
 
         List<Collection>? items = null;
         int total = 0;
@@ -71,6 +58,17 @@ public async Task<CollectionWithItems> Handle(GetCollection request,
             if (collection.Parent != null)
             {
                 collection.FullPath = CollectionRetrieval.RetrieveFullPathForCollection(collection, dbContext);
+
+                var parentCollection = await dbContext.RetrieveCollection(request.CustomerId, collection.Parent, RootCollection.Id, 
+                    cancellationToken);
+                if (parentCollection!.Parent == null)
+                {
+                    collection.Parent = RootCollection.Id;
+                }
+            }
+            else
+            {
+                collection.Id = RootCollection.Id;
             }
         }
 

src/IIIFPresentation/API/Features/Storage/Requests/UpdateCollection.cs

@@ -1,6 +1,7 @@
 using API.Auth;
 using API.Converters;
 using API.Features.Storage.Helpers;
+using API.Helpers;
 using API.Infrastructure.Requests;
 using API.Settings;
 using Core;
@@ -47,13 +48,22 @@ public async Task<ModifyEntityResult<FlatCollection>> Handle(UpdateCollection re
             return ModifyEntityResult<FlatCollection>.Failure(
                 "Could not find a matching record for the provided collection id", WriteResult.NotFound);
         }
+
+        var parentCollection = await dbContext.RetrieveCollection(request.CustomerId,
+            request.Collection.Parent.GetLastPathElement(), RootCollection.Id, cancellationToken);
+
+        if (parentCollection == null)
+        {
+            return ModifyEntityResult<FlatCollection>.Failure(
+                $"The parent collection could not be found", WriteResult.Conflict);
+        }
 
         collectionFromDatabase.Modified = DateTime.UtcNow;
         collectionFromDatabase.ModifiedBy = Authorizer.GetUser();
         collectionFromDatabase.IsPublic = request.Collection.Behavior.IsPublic();
         collectionFromDatabase.IsStorageCollection = request.Collection.Behavior.IsStorageCollection();
         collectionFromDatabase.Label = request.Collection.Label;
-        collectionFromDatabase.Parent = request.Collection.Parent.GetLastPathElement();
+        collectionFromDatabase.Parent = parentCollection.Id;
         collectionFromDatabase.Slug = request.Collection.Slug;
         collectionFromDatabase.Thumbnail = request.Collection.Thumbnail;
         collectionFromDatabase.Tags = request.Collection.Tags;
@@ -85,6 +95,8 @@ public async Task<ModifyEntityResult<FlatCollection>> Handle(UpdateCollection re
                 CollectionRetrieval.RetrieveFullPathForCollection(collectionFromDatabase, dbContext);
         }
 
+        collectionFromDatabase.UpdateParentForRootIfRequired(request.Collection.Parent);
+
         return ModifyEntityResult<FlatCollection>.Success(
             collectionFromDatabase.ToFlatCollection(request.UrlRoots, settings.PageSize, DefaultCurrentPage, total,
                 await items.ToListAsync(cancellationToken: cancellationToken)));

src/IIIFPresentation/API/Helpers/CollectionHelperX.cs

@@ -1,4 +1,6 @@
 using API.Converters;
+using API.Features.Storage.Helpers;
+using Core.Helpers;
 using Models.Database.Collections;
 
 namespace API.Helpers;
@@ -43,4 +45,15 @@ public static Uri GenerateFlatCollectionViewLast(this Collection collection, Url
 
     public static string GenerateFullPath(this Collection collection, string itemSlug) => 
         $"{(collection.Parent != null ? $"{collection.Slug}/" : string.Empty)}{itemSlug}";
+
+    public static Collection UpdateParentForRootIfRequired(this Collection collection, string parentToChangeTo)
+    {
+        // everything saved so set the response value to be the root collection if required
+        if (parentToChangeTo.GetLastPathElement() == RootCollection.Id)
+        {
+            collection.Parent = RootCollection.Id;
+        }
+
+        return collection;
+    }
 }