Trial - boosting prospect grid loading performance

.github/prompts/plan-prospectPerformance.prompt.md

@@ -0,0 +1,56 @@
+## Plan: Prospect list performance overhaul
+
+The current bottleneck is not just data volume; it is the combination of loading every prospect and every nested interaction at once, then rendering all cards in the browser. In the current flow, each page loads the full list from `ProspectService.GetProspectsAsync`, includes all `Images` and `Interactions` plus each `User`, and then `ProspectGrid` renders every card through `Repeater` without virtualization. With hundreds of records, the UI does repeated LINQ work per card and hits a lot of DOM work in one render.
+
+### Recommended approach
+Use a two-part fix: reduce the server-side payload and virtualize the client-side rendering. The best gains will come from paginating or virtualizing the list, then trimming unnecessary nested load and repeated per-row calculations.
+
+### Steps
+1. Profile the bottleneck and cap the visible list size
+   - Confirm the prospect pages are loading all records at once because `GetProspectsAsync` currently does `ToListAsync()` without paging or limit.
+   - Add a page-size/virtualized flow so only the visible slice is fetched and rendered.
+   - This change must happen in the page and service layer before any UI refactor.
+
+2. Reduce EF payload in `ProspectService.GetProspectsAsync`
+   - Update `FoodsharingSiegen.Server/Data/Service/ProspectService.cs` so it accepts pagination arguments (`skip`, `take`, optional filters) instead of returning the full unbounded list.
+   - Keep the query as `AsNoTracking()` but avoid eager-loading all `Images` and every `User` for every prospect when the page only needs a summary view.
+   - For the list pages, load only the subset needed for the grid and defer expensive image/user data until a detail action opens.
+   - Filter and sort should happen server-side when possible to avoid moving hundreds of full entities into memory and then filtering again in the browser.
+
+3. Replace the full list render with virtualization
+   - Convert the repeated list in `FoodsharingSiegen.Server/Controls/ProspectGrid.razor` to a virtualized list or paged container, rather than rendering a full `<Repeater Items="@Prospects">` for all rows.
+   - Keep the visible cards only; the hidden rows should not be in the DOM.
+   - This removes the biggest DOM cost on pages with hundreds of entries.
+
+4. Remove repeated per-row computation in the card components
+   - In `FoodsharingSiegen.Server/Controls/InteractionRow.razor.cs`, the properties `Interactions`, `Done`, `Alert`, `NotNeeded` recalculate on every render from a list of nested items. With hundreds of cards this becomes expensive.
+   - Replace repeated `Where()` chains with precomputed values from the loaded model or cached values at the prospect object level.
+   - In `FoodsharingSiegen.Contracts/Entity/Prospect.cs`, avoid deriving `Complete` from `Interactions.Any()` on every render when a summary value is already known in the data model.
+   - Keep the card logic free of repeated `ToList()` and `Any()` chains during render.
+
+5. Tighten data shaping for each list page
+   - The onboarding, verification, archive, and done pages all load the same full set of entities and then apply client-side filters with `ApplyFilter` and `ApplySort` in `FoodsharingSiegen.Shared/Helper/FilterHelper.cs`.
+   - Move the expensive filtering/sorting to SQL or at least to the server-side query layer; reduce the list to a smaller result set before it reaches the UI.
+   - Keep `ProspectList.ApplyFilter` only as a fallback for small local slices, not as the primary path for large lists.
+
+6. Verify the improvement with focused checks
+   - Measure page load time before and after with a realistic dataset of several hundred prospects.
+   - Validate that the list stays responsive during scrolling and interaction changes.
+   - Run the relevant .NET tests and render-check the prospect pages manually.
+
+### Relevant files
+- `FoodsharingSiegen.Server/Data/Service/ProspectService.cs` — main query and database fetch point.
+- `FoodsharingSiegen.Server/Controls/ProspectGrid.razor` — full-list rendering path.
+- `FoodsharingSiegen.Server/Controls/ProspectContainer.razor` — per-card DOM and nested component rendering.
+- `FoodsharingSiegen.Server/Controls/InteractionRow.razor.cs` — repeated LINQ work in each row.
+- `FoodsharingSiegen.Contracts/Entity/Prospect.cs` — computed values that trigger repeated work.
+- `FoodsharingSiegen.Shared/Helper/FilterHelper.cs` — client-side list filtering/sorting on large sets.
+- `FoodsharingSiegen.Server/Pages/Prospects.razor`, `FoodsharingSiegen.Server/Pages/ProspectsAll.razor`, `FoodsharingSiegen.Server/Pages/ProspectsVerify.razor`, `FoodsharingSiegen.Server/Pages/ProspectsDone.razor` — list page orchestration and data flow.
+
+### Key decision
+The highest-value fix is to stop returning and rendering all prospects at once. A virtualized/paged list with a trimmed query shape will provide the biggest speedup and should be the first implementation target.
+
+### Optional follow-up improvements
+- Precompute a lightweight summary model for the grid instead of the full `Prospect` entity.
+- Add a server-side count query to support proper paging without loading every record.
+- Consider splitting the list into “summary” and “detail” data so the main dashboard never loads full nested relationship graphs by default.

FoodsharingSiegen.Contracts/Model/Parameters.cs

@@ -6,5 +6,10 @@ namespace FoodsharingSiegen.Contracts.Model
     /// <summary>
     ///     The get prospects parameter
     /// </summary>
-    public record GetProspectsParameter(List<InteractionType>? MustHaveInteractions = null, List<InteractionType>? CannotHaveInteractions = null, bool IncludeDeleted = false);
+    public record GetProspectsParameter(
+        List<InteractionType>? MustHaveInteractions = null,
+        List<InteractionType>? CannotHaveInteractions = null,
+        bool IncludeDeleted = false,
+        int Skip = 0,
+        int Take = 50);
 }

FoodsharingSiegen.Server/Controls/InteractionRow.razor.cs

@@ -97,7 +97,9 @@ namespace FoodsharingSiegen.Server.Controls
         /// <summary>
         ///     Gets the value of the interactions (ab)
         /// </summary>
-        private List<Interaction> Interactions => Prospect?.Interactions.Where(x => x.Type == Type).ToList() ?? [];
+        private List<Interaction> Interactions => Prospect?.Interactions is null
+            ? []
+            : [.. Prospect.Interactions.Where(x => x.Type == Type)];
 
         /// <summary>
         ///     Gets the value of the not needed (ab)

FoodsharingSiegen.Server/Controls/ProspectGrid.razor

@@ -1,4 +1,7 @@
 @using FoodsharingSiegen.Contracts.Enums
+@using Microsoft.JSInterop
+@implements IAsyncDisposable
+@inject IJSRuntime JSRuntime
 @code {
 
   [Parameter] public List<Prospect>? Prospects { get; set; }
@@ -7,19 +10,95 @@
   
   [Parameter] public Func<Task>? OnDataChanged { get; set; }
 
+  [Parameter] public EventCallback OnLoadMore { get; set; }
+
+  [Parameter] public bool IsLoadingMore { get; set; }
+
+  [Parameter] public bool HasMore { get; set; }
+
   [Parameter] public string GridClass { get; set; } = string.Empty;
 
+  private IJSObjectReference? _module;
+  private DotNetObjectReference<ProspectGrid>? _dotNetHelper;
+  private string _gridId = $"prospect-grid-{Guid.NewGuid():N}";
+  private bool _isJsBound;
+  private bool _disposed;
+
+  protected override async Task OnAfterRenderAsync(bool firstRender)
+  {
+      if (_disposed || !firstRender || _isJsBound) return;
+
+      try
+      {
+          _dotNetHelper ??= DotNetObjectReference.Create(this);
+          _module ??= await JSRuntime.InvokeAsync<IJSObjectReference>("import", "./js/prospect-grid.js");
+          await _module.InvokeVoidAsync("attachScrollLoader", _gridId, _dotNetHelper);
+          _isJsBound = true;
+      }
+      catch (JSDisconnectedException)
+      {
+          // Ignore browser disconnect during teardown.
+      }
+      catch (ObjectDisposedException)
+      {
+          // Ignore late render after the component is being torn down.
+      }
+  }
+
+  [JSInvokable]
+  public async Task OnScrollNearBottom()
+  {
+      if (OnLoadMore.HasDelegate && !IsLoadingMore && HasMore)
+      {
+         await OnLoadMore.InvokeAsync();
+      }
+  }
+
+  public async ValueTask DisposeAsync()
+  {
+      _disposed = true;
+
+      if (_module is not null)
+      {
+          try
+          {
+              await _module.InvokeVoidAsync("disposeScrollLoader", _gridId);
+          }
+          catch (JSDisconnectedException)
+          {
+              // ignored; the circuit is already disconnected
+          }
+          catch (ObjectDisposedException)
+          {
+              // ignored; the JS runtime is already disposed
+          }
+      }
+
+      _dotNetHelper?.Dispose();
+      _dotNetHelper = null;
+      _isJsBound = false;
+  }
+
 }
 <h6>@(Prospects?.Count ?? 0) Ergebnisse</h6>
 
 @if (Prospects?.Any() == true)
 {
-  <div class="prospect-grid @GridClass">
-    <Repeater Items="@Prospects">
-      <ProspectContainer 
-        Prospect="context" 
+  <div id="@_gridId" class="prospect-grid @GridClass" style="max-height: calc(100vh - 250px); overflow-y: auto;">
+    @foreach (var prospect in Prospects)
+    {
+      <ProspectContainer @key="prospect.Id"
+        Prospect="prospect" 
         OnDataChanged="@OnDataChanged"
         StateFilter="StateFilter"></ProspectContainer>
-    </Repeater>
+    }
+
+    @if (IsLoadingMore)
+    {
+      <div class="d-flex justify-content-center py-3 text-muted">
+        <span class="me-2"><i class="fa-solid fa-spinner fa-spin"></i></span>
+        Weitere laden...
+      </div>
+    }
   </div>
 }

FoodsharingSiegen.Server/Data/Service/ProspectService.cs

@@ -115,18 +115,24 @@ namespace FoodsharingSiegen.Server.Data.Service
                     .Include(x => x.Images)
                     .Include(x => x.Interactions.OrderBy(i => i.Date)).ThenInclude(x => x.User)
                     .OrderBy(x => x.Name).AsQueryable();
-                
-                if(parameter.MustHaveInteractions != null && parameter.MustHaveInteractions.Any()) 
+
+                if (parameter.MustHaveInteractions != null && parameter.MustHaveInteractions.Any())
                     prospectsQuery = prospectsQuery.Where(x => x.Interactions.Any(i => parameter.MustHaveInteractions.Contains(i.Type)));
-                
-                if(parameter.CannotHaveInteractions != null && parameter.CannotHaveInteractions.Any())
+
+                if (parameter.CannotHaveInteractions != null && parameter.CannotHaveInteractions.Any())
                     prospectsQuery = prospectsQuery.Where(x => x.Interactions.All(i => !parameter.CannotHaveInteractions.Contains(i.Type)));
 
-                if (!parameter.IncludeDeleted) 
+                if (!parameter.IncludeDeleted)
                     prospectsQuery = prospectsQuery.Where(x => x.RecordState != RecordState.Archived);
-                
+
+                if (parameter.Skip > 0)
+                    prospectsQuery = prospectsQuery.Skip(parameter.Skip);
+
+                if (parameter.Take > 0)
+                    prospectsQuery = prospectsQuery.Take(parameter.Take);
+
                 var prospects = await prospectsQuery.ToListAsync();
-                
+
                 return new(prospects);
             }
             catch (Exception e)

FoodsharingSiegen.Server/Pages/Prospects.razor

@@ -29,13 +29,25 @@
 <ProspectSortControl @bind-CurrentSort="CurrentSort" StorageKey="@StorageKeys.SortProspects" OnSortChanged="StateHasChanged" Filter="Filter" FilterChanged="FilterChangedAsync" StateFilter="ProspectStateFilter.OnBoarding" />
 
 @{
-    var filterList = ProspectList.ApplyFilter(Filter);
-    var sortList = filterList.ApplySort(CurrentSort);
+    var filtered = ProspectList.ApplyFilter(Filter);
+    var sortList = filtered.ApplySort(CurrentSort);
 }
 
-
-<ProspectGrid
-    Prospects="sortList"
-    OnDataChanged="@LoadProspects"
-    StateFilter="ProspectStateFilter.OnBoarding">
-</ProspectGrid>
+@if (IsLoadingProspects)
+{
+    <div class="d-flex justify-content-center align-items-center py-5 text-muted">
+        <span class="me-2"><i class="fa-solid fa-spinner fa-spin"></i></span>
+        Lade Einarbeitungen...
+    </div>
+}
+else
+{
+    <ProspectGrid
+        Prospects="sortList"
+        OnDataChanged="@LoadProspects"
+        OnLoadMore="@LoadMoreProspects"
+        IsLoadingMore="IsLoadingMoreProspects"
+        HasMore="HasMoreProspects"
+        StateFilter="ProspectStateFilter.OnBoarding">
+    </ProspectGrid>
+}

FoodsharingSiegen.Server/Pages/Prospects.razor.cs

@@ -3,6 +3,7 @@ using FoodsharingSiegen.Contracts.Entity;
 using FoodsharingSiegen.Contracts.Enums;
 using FoodsharingSiegen.Contracts.Model;
 using FoodsharingSiegen.Server.Data.Service;
+using FoodsharingSiegen.Shared.Helper;
 using FoodsharingSiegen.Server.Dialogs;
 using FoodsharingSiegen.Server.Service;
 using Microsoft.AspNetCore.Components;
@@ -34,7 +35,17 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Gets or sets the value of the prospect list (ab)
         /// </summary>
-        private List<Prospect>? ProspectList { get; set; }
+        private List<Prospect> ProspectList { get; set; } = [];
+
+        private bool IsLoadingProspects { get; set; }
+
+        private bool IsLoadingMoreProspects { get; set; }
+
+        private bool HasMoreProspects { get; set; }
+
+        private int CurrentPageSize { get; set; } = 50;
+
+        private int CurrentSkip { get; set; }
 
         private ProspectSortOption CurrentSort { get; set; } = ProspectSortOption.NameAscending;
 
@@ -89,6 +100,9 @@ namespace FoodsharingSiegen.Server.Pages
         {
             Filter = arg;
             await LocalStorageService.SetItem(StorageKeys.ProspectFilter, Filter);
+            CurrentSkip = 0;
+            ProspectList = [];
+            await LoadProspects();
         }
 
         #endregion
@@ -98,17 +112,68 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Loads the prospects (a. beging, 11.04.2022)
         /// </summary>
+        private bool HasActiveFilter()
+        {
+            return !string.IsNullOrWhiteSpace(Filter.Text)
+                || Filter.WithoutStepInBriefing
+                || Filter.WithoutIdCheck
+                || Filter.DeletedOnly
+                || Filter.IdCheckPossible
+                || Filter.NoActivity
+                || Filter.RecentActivity;
+        }
+
         private async Task LoadProspects()
         {
+            if (IsLoadingProspects || IsLoadingMoreProspects) return;
+
             try
             {
-                var parameter = new GetProspectsParameter
+                if (CurrentSkip == 0)
                 {
-                    CannotHaveInteractions = [InteractionType.Complete, InteractionType.Verify, InteractionType.ReleasedForVerification]
-                };
+                    IsLoadingProspects = true;
+                }
+                else
+                {
+                    IsLoadingMoreProspects = true;
+                }
 
-                var prospectsR = await ProspectService.GetProspectsAsync(parameter);
-                if (prospectsR.Success) ProspectList = prospectsR.Data;
+                await InvokeAsync(StateHasChanged);
+
+                while (true)
+                {
+                    var parameter = new GetProspectsParameter
+                    {
+                        Skip = CurrentSkip,
+                        Take = CurrentPageSize,
+                        CannotHaveInteractions = [InteractionType.Complete, InteractionType.Verify, InteractionType.ReleasedForVerification]
+                    };
+
+                    var prospectsR = await ProspectService.GetProspectsAsync(parameter);
+                    if (!prospectsR.Success)
+                    {
+                        break;
+                    }
+
+                    var loadedProspects = prospectsR.Data ?? [];
+                    if (CurrentSkip == 0)
+                    {
+                        ProspectList = loadedProspects;
+                    }
+                    else
+                    {
+                        ProspectList = [.. ProspectList, .. loadedProspects];
+                    }
+
+                    CurrentSkip += loadedProspects.Count;
+                    HasMoreProspects = loadedProspects.Count == CurrentPageSize;
+
+                    var filteredCount = ProspectList.ApplyFilter(Filter).Count;
+                    if (!HasActiveFilter() || filteredCount > 0 || !HasMoreProspects || loadedProspects.Count == 0)
+                    {
+                        break;
+                    }
+                }
 
                 await InvokeAsync(StateHasChanged);
             }
@@ -116,6 +181,18 @@ namespace FoodsharingSiegen.Server.Pages
             {
                 await Notification.Error(ex.Message, "Fehler beim Laden");
             }
+            finally
+            {
+                IsLoadingProspects = false;
+                IsLoadingMoreProspects = false;
+                await InvokeAsync(StateHasChanged);
+            }
+        }
+
+        private async Task LoadMoreProspects()
+        {
+            if (IsLoadingProspects || IsLoadingMoreProspects || !HasMoreProspects) return;
+            await LoadProspects();
         }
 
         #endregion

FoodsharingSiegen.Server/Pages/ProspectsAll.razor

@@ -17,12 +17,25 @@
 <ProspectSortControl @bind-CurrentSort="CurrentSort" StorageKey="@StorageKeys.SortProspectsAll" OnSortChanged="StateHasChanged" Filter="Filter" FilterChanged="FilterChangedAsync" StateFilter="ProspectStateFilter.All" />
 
 @{
-    var filterList = ProspectList.ApplyFilter(Filter);
-    var sortList = filterList.ApplySort(CurrentSort);
+    var filtered = ProspectList.ApplyFilter(Filter);
+    var sortList = filtered.ApplySort(CurrentSort);
 }
 
-<ProspectGrid
-    Prospects="sortList"
-    OnDataChanged="@LoadProspects"
-    StateFilter="ProspectStateFilter.All">
-</ProspectGrid>
+@if (IsLoadingProspects)
+{
+    <div class="d-flex justify-content-center align-items-center py-5 text-muted">
+        <span class="me-2"><i class="fa-solid fa-spinner fa-spin"></i></span>
+        Lade Einarbeitungen...
+    </div>
+}
+else
+{
+    <ProspectGrid
+        Prospects="sortList"
+        OnDataChanged="@LoadProspects"
+        OnLoadMore="@LoadMoreProspects"
+        IsLoadingMore="IsLoadingMoreProspects"
+        HasMore="HasMoreProspects"
+        StateFilter="ProspectStateFilter.All">
+    </ProspectGrid>
+}

FoodsharingSiegen.Server/Pages/ProspectsAll.razor.cs

@@ -5,6 +5,7 @@ using FoodsharingSiegen.Contracts.Helper;
 using FoodsharingSiegen.Contracts.Model;
 using FoodsharingSiegen.Server.Data.Service;
 using FoodsharingSiegen.Server.Dialogs;
+using FoodsharingSiegen.Shared.Helper;
 using Microsoft.AspNetCore.Components;
 
 namespace FoodsharingSiegen.Server.Pages
@@ -37,7 +38,17 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Gets or sets the value of the prospect list (ab)
         /// </summary>
-        private List<Prospect>? ProspectList { get; set; }
+        private List<Prospect> ProspectList { get; set; } = [];
+
+        private bool IsLoadingProspects { get; set; }
+
+        private bool IsLoadingMoreProspects { get; set; }
+
+        private bool HasMoreProspects { get; set; }
+
+        private int CurrentPageSize { get; set; } = 50;
+
+        private int CurrentSkip { get; set; }
 
         private ProspectSortOption CurrentSort { get; set; } = ProspectSortOption.NameAscending;
 
@@ -71,6 +82,9 @@ namespace FoodsharingSiegen.Server.Pages
         {
             Filter = arg;
             await LocalStorageService.SetItem(StorageKeys.ProspectFilter, Filter);
+            CurrentSkip = 0;
+            ProspectList = [];
+            await LoadProspects();
         }
 
         #endregion
@@ -80,17 +94,83 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Loads the prospects (a. beging, 11.04.2022)
         /// </summary>
+        private bool HasActiveFilter()
+        {
+            return !string.IsNullOrWhiteSpace(Filter.Text)
+                || Filter.WithoutStepInBriefing
+                || Filter.WithoutIdCheck
+                || Filter.DeletedOnly
+                || Filter.IdCheckPossible
+                || Filter.NoActivity
+                || Filter.RecentActivity;
+        }
+
         private async Task LoadProspects()
         {
-            var parameter = new GetProspectsParameter
-            {
-                IncludeDeleted = true
-            };
-            
-            var prospectsR = await ProspectService.GetProspectsAsync(parameter);
-            if (prospectsR.Success) ProspectList = prospectsR.Data;
+            if (IsLoadingProspects || IsLoadingMoreProspects) return;
 
-            await InvokeAsync(StateHasChanged);
+            try
+            {
+                if (CurrentSkip == 0)
+                {
+                    IsLoadingProspects = true;
+                }
+                else
+                {
+                    IsLoadingMoreProspects = true;
+                }
+
+                await InvokeAsync(StateHasChanged);
+
+                while (true)
+                {
+                    var parameter = new GetProspectsParameter
+                    {
+                        Skip = CurrentSkip,
+                        Take = CurrentPageSize,
+                        IncludeDeleted = true
+                    };
+
+                    var prospectsR = await ProspectService.GetProspectsAsync(parameter);
+                    if (!prospectsR.Success)
+                    {
+                        break;
+                    }
+
+                    var loadedProspects = prospectsR.Data ?? [];
+                    if (CurrentSkip == 0)
+                    {
+                        ProspectList = loadedProspects;
+                    }
+                    else
+                    {
+                        ProspectList = [.. ProspectList, .. loadedProspects];
+                    }
+
+                    CurrentSkip += loadedProspects.Count;
+                    HasMoreProspects = loadedProspects.Count == CurrentPageSize;
+
+                    var filteredCount = ProspectList.ApplyFilter(Filter).Count;
+                    if (!HasActiveFilter() || filteredCount > 0 || !HasMoreProspects || loadedProspects.Count == 0)
+                    {
+                        break;
+                    }
+                }
+
+                await InvokeAsync(StateHasChanged);
+            }
+            finally
+            {
+                IsLoadingProspects = false;
+                IsLoadingMoreProspects = false;
+                await InvokeAsync(StateHasChanged);
+            }
+        }
+
+        private async Task LoadMoreProspects()
+        {
+            if (IsLoadingProspects || IsLoadingMoreProspects || !HasMoreProspects) return;
+            await LoadProspects();
         }
 
         #endregion

FoodsharingSiegen.Server/Pages/ProspectsDone.razor

@@ -16,12 +16,25 @@
 <ProspectSortControl @bind-CurrentSort="CurrentSort" StorageKey="@StorageKeys.SortProspectsDone" OnSortChanged="StateHasChanged" Filter="Filter" FilterChanged="FilterChangedAsync" StateFilter="ProspectStateFilter.Completed" />
 
 @{
-    var filterList = ProspectList.ApplyFilter(Filter);
-    var sortList = filterList.ApplySort(CurrentSort);
+    var filtered = ProspectList.ApplyFilter(Filter);
+    var sortList = filtered.ApplySort(CurrentSort);
 }
 
-<ProspectGrid
-    Prospects="sortList"
-    OnDataChanged="@LoadProspects"
-    StateFilter="ProspectStateFilter.Completed">
-</ProspectGrid>
+@if (IsLoadingProspects)
+{
+    <div class="d-flex justify-content-center align-items-center py-5 text-muted">
+        <span class="me-2"><i class="fa-solid fa-spinner fa-spin"></i></span>
+        Lade Einarbeitungen...
+    </div>
+}
+else
+{
+    <ProspectGrid
+        Prospects="sortList"
+        OnDataChanged="@LoadProspects"
+        OnLoadMore="@LoadMoreProspects"
+        IsLoadingMore="IsLoadingMoreProspects"
+        HasMore="HasMoreProspects"
+        StateFilter="ProspectStateFilter.Completed">
+    </ProspectGrid>
+}

FoodsharingSiegen.Server/Pages/ProspectsDone.razor.cs

@@ -3,6 +3,7 @@ using FoodsharingSiegen.Contracts.Entity;
 using FoodsharingSiegen.Contracts.Enums;
 using FoodsharingSiegen.Contracts.Model;
 using FoodsharingSiegen.Server.Data.Service;
+using FoodsharingSiegen.Shared.Helper;
 using Microsoft.AspNetCore.Components;
 
 namespace FoodsharingSiegen.Server.Pages
@@ -29,7 +30,17 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Gets or sets the value of the prospect list (ab)
         /// </summary>
-        private List<Prospect>? ProspectList { get; set; }
+        private List<Prospect> ProspectList { get; set; } = [];
+
+        private bool IsLoadingProspects { get; set; }
+
+        private bool IsLoadingMoreProspects { get; set; }
+
+        private bool HasMoreProspects { get; set; }
+
+        private int CurrentPageSize { get; set; } = 50;
+
+        private int CurrentSkip { get; set; }
 
         private ProspectSortOption CurrentSort { get; set; } = ProspectSortOption.NameAscending;
 
@@ -60,6 +71,9 @@ namespace FoodsharingSiegen.Server.Pages
         {
             Filter = arg;
             await LocalStorageService.SetItem(StorageKeys.ProspectFilter, Filter);
+            CurrentSkip = 0;
+            ProspectList = [];
+            await LoadProspects();
         }
 
         #endregion
@@ -69,13 +83,82 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Loads the prospects (a. beging, 11.04.2022)
         /// </summary>
+        private bool HasActiveFilter()
+        {
+            return !string.IsNullOrWhiteSpace(Filter.Text)
+                || Filter.WithoutStepInBriefing
+                || Filter.WithoutIdCheck
+                || Filter.DeletedOnly
+                || Filter.IdCheckPossible
+                || Filter.NoActivity
+                || Filter.RecentActivity;
+        }
+
         private async Task LoadProspects()
         {
-            var parameter = new GetProspectsParameter { MustHaveInteractions = [InteractionType.Complete] };
-            var prospectsR = await ProspectService.GetProspectsAsync(parameter);
-            if (prospectsR.Success) ProspectList = prospectsR.Data;
+            if (IsLoadingProspects || IsLoadingMoreProspects) return;
 
-            await InvokeAsync(StateHasChanged);
+            try
+            {
+                if (CurrentSkip == 0)
+                {
+                    IsLoadingProspects = true;
+                }
+                else
+                {
+                    IsLoadingMoreProspects = true;
+                }
+
+                await InvokeAsync(StateHasChanged);
+
+                while (true)
+                {
+                    var parameter = new GetProspectsParameter
+                    {
+                        Skip = CurrentSkip,
+                        Take = CurrentPageSize,
+                        MustHaveInteractions = [InteractionType.Complete]
+                    };
+                    var prospectsR = await ProspectService.GetProspectsAsync(parameter);
+                    if (!prospectsR.Success)
+                    {
+                        break;
+                    }
+
+                    var loadedProspects = prospectsR.Data ?? [];
+                    if (CurrentSkip == 0)
+                    {
+                        ProspectList = loadedProspects;
+                    }
+                    else
+                    {
+                        ProspectList = [.. ProspectList, .. loadedProspects];
+                    }
+
+                    CurrentSkip += loadedProspects.Count;
+                    HasMoreProspects = loadedProspects.Count == CurrentPageSize;
+
+                    var filteredCount = ProspectList.ApplyFilter(Filter).Count;
+                    if (!HasActiveFilter() || filteredCount > 0 || !HasMoreProspects || loadedProspects.Count == 0)
+                    {
+                        break;
+                    }
+                }
+
+                await InvokeAsync(StateHasChanged);
+            }
+            finally
+            {
+                IsLoadingProspects = false;
+                IsLoadingMoreProspects = false;
+                await InvokeAsync(StateHasChanged);
+            }
+        }
+
+        private async Task LoadMoreProspects()
+        {
+            if (IsLoadingProspects || IsLoadingMoreProspects || !HasMoreProspects) return;
+            await LoadProspects();
         }
 
         #endregion

FoodsharingSiegen.Server/Pages/ProspectsVerify.razor

@@ -16,13 +16,25 @@
 <ProspectSortControl @bind-CurrentSort="CurrentSort" StorageKey="@StorageKeys.SortProspectsVerify" OnSortChanged="StateHasChanged" Filter="Filter" FilterChanged="FilterChangedAsync" StateFilter="ProspectStateFilter.Verification" />
 
 @{
-    var filterList = ProspectList.ApplyFilter(Filter);
-    var sortList = filterList.ApplySort(CurrentSort);
+    var filtered = ProspectList.ApplyFilter(Filter);
+    var sortList = filtered.ApplySort(CurrentSort);
 }
 
-
-<ProspectGrid
-    Prospects="sortList"
-    OnDataChanged="@LoadProspects"
-    StateFilter="ProspectStateFilter.Verification">
-</ProspectGrid>
+@if (IsLoadingProspects)
+{
+    <div class="d-flex justify-content-center align-items-center py-5 text-muted">
+        <span class="me-2"><i class="fa-solid fa-spinner fa-spin"></i></span>
+        Lade Einarbeitungen...
+    </div>
+}
+else
+{
+    <ProspectGrid
+        Prospects="sortList"
+        OnDataChanged="@LoadProspects"
+        OnLoadMore="@LoadMoreProspects"
+        IsLoadingMore="IsLoadingMoreProspects"
+        HasMore="HasMoreProspects"
+        StateFilter="ProspectStateFilter.Verification">
+    </ProspectGrid>
+}

FoodsharingSiegen.Server/Pages/ProspectsVerify.razor.cs

@@ -3,6 +3,7 @@ using FoodsharingSiegen.Contracts.Entity;
 using FoodsharingSiegen.Contracts.Enums;
 using FoodsharingSiegen.Contracts.Model;
 using FoodsharingSiegen.Server.Data.Service;
+using FoodsharingSiegen.Shared.Helper;
 using Microsoft.AspNetCore.Components;
 
 namespace FoodsharingSiegen.Server.Pages
@@ -35,7 +36,17 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Gets or sets the value of the prospect list (ab)
         /// </summary>
-        private List<Prospect>? ProspectList { get; set; }
+        private List<Prospect> ProspectList { get; set; } = [];
+
+        private bool IsLoadingProspects { get; set; }
+
+        private bool IsLoadingMoreProspects { get; set; }
+
+        private bool HasMoreProspects { get; set; }
+
+        private int CurrentPageSize { get; set; } = 50;
+
+        private int CurrentSkip { get; set; }
 
         private ProspectSortOption CurrentSort { get; set; } = ProspectSortOption.NameAscending;
 
@@ -67,6 +78,9 @@ namespace FoodsharingSiegen.Server.Pages
         {
             Filter = arg;
             await LocalStorageService.SetItem(StorageKeys.ProspectFilter, Filter);
+            CurrentSkip = 0;
+            ProspectList = [];
+            await LoadProspects();
         }
 
         #endregion
@@ -76,17 +90,83 @@ namespace FoodsharingSiegen.Server.Pages
         /// <summary>
         ///     Loads the prospects (a. beging, 11.04.2022)
         /// </summary>
+        private bool HasActiveFilter()
+        {
+            return !string.IsNullOrWhiteSpace(Filter.Text)
+                || Filter.WithoutStepInBriefing
+                || Filter.WithoutIdCheck
+                || Filter.DeletedOnly
+                || Filter.IdCheckPossible
+                || Filter.NoActivity
+                || Filter.RecentActivity;
+        }
+
         private async Task LoadProspects()
         {
-            var parameter = new GetProspectsParameter
-            {
-                CannotHaveInteractions = [InteractionType.Complete],
-                MustHaveInteractions = [InteractionType.ReleasedForVerification]
-            };
-            var prospectsR = await ProspectService.GetProspectsAsync(parameter);
-            if (prospectsR.Success) ProspectList = prospectsR.Data;
+            if (IsLoadingProspects || IsLoadingMoreProspects) return;
 
-            await InvokeAsync(StateHasChanged);
+            try
+            {
+                if (CurrentSkip == 0)
+                {
+                    IsLoadingProspects = true;
+                }
+                else
+                {
+                    IsLoadingMoreProspects = true;
+                }
+
+                await InvokeAsync(StateHasChanged);
+
+                while (true)
+                {
+                    var parameter = new GetProspectsParameter
+                    {
+                        Skip = CurrentSkip,
+                        Take = CurrentPageSize,
+                        CannotHaveInteractions = [InteractionType.Complete],
+                        MustHaveInteractions = [InteractionType.ReleasedForVerification]
+                    };
+                    var prospectsR = await ProspectService.GetProspectsAsync(parameter);
+                    if (!prospectsR.Success)
+                    {
+                        break;
+                    }
+
+                    var loadedProspects = prospectsR.Data ?? [];
+                    if (CurrentSkip == 0)
+                    {
+                        ProspectList = loadedProspects;
+                    }
+                    else
+                    {
+                        ProspectList = [.. ProspectList, .. loadedProspects];
+                    }
+
+                    CurrentSkip += loadedProspects.Count;
+                    HasMoreProspects = loadedProspects.Count == CurrentPageSize;
+
+                    var filteredCount = ProspectList.ApplyFilter(Filter).Count;
+                    if (!HasActiveFilter() || filteredCount > 0 || !HasMoreProspects || loadedProspects.Count == 0)
+                    {
+                        break;
+                    }
+                }
+
+                await InvokeAsync(StateHasChanged);
+            }
+            finally
+            {
+                IsLoadingProspects = false;
+                IsLoadingMoreProspects = false;
+                await InvokeAsync(StateHasChanged);
+            }
+        }
+
+        private async Task LoadMoreProspects()
+        {
+            if (IsLoadingProspects || IsLoadingMoreProspects || !HasMoreProspects) return;
+            await LoadProspects();
         }
 
         #endregion

FoodsharingSiegen.Server/wwwroot/js/prospect-grid.js

@@ -0,0 +1,23 @@
+export function attachScrollLoader(gridId, component) {
+    const grid = document.getElementById(gridId);
+    if (!grid) return;
+
+    const checkScroll = () => {
+        const distanceFromBottom = grid.scrollHeight - (grid.scrollTop + grid.clientHeight);
+        if (distanceFromBottom < 250) {
+            component.invokeMethodAsync('OnScrollNearBottom');
+        }
+    };
+
+    grid.addEventListener('scroll', checkScroll, { passive: true });
+    grid.__prospectScrollCheck = checkScroll;
+    checkScroll();
+}
+
+export function disposeScrollLoader(gridId) {
+    const grid = document.getElementById(gridId);
+    if (!grid || !grid.__prospectScrollCheck) return;
+
+    grid.removeEventListener('scroll', grid.__prospectScrollCheck);
+    delete grid.__prospectScrollCheck;
+}

FoodsharingSiegen.Tests/ProspectServiceTests.cs

@@ -0,0 +1,74 @@
+using FoodsharingSiegen.Contracts.Entity;
+using FoodsharingSiegen.Contracts.Enums;
+using FoodsharingSiegen.Contracts.Model;
+using FoodsharingSiegen.Server.Auth;
+using FoodsharingSiegen.Server.Data;
+using FoodsharingSiegen.Server.Data.Service;
+using FoodsharingSiegen.Server.Service;
+using Microsoft.AspNetCore.Components.Authorization;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
+using Microsoft.JSInterop;
+using Moq;
+using Xunit;
+
+namespace FoodsharingSiegen.Tests;
+
+public class ProspectServiceTests
+{
+    private static FsContext CreateInMemoryContext(string dbName)
+    {
+        var options = new DbContextOptionsBuilder<FsContext>()
+            .UseInMemoryDatabase(databaseName: dbName)
+            .Options;
+
+        return new FsContext(options);
+    }
+
+    private static AuthService CreateAuthService(FsContext context)
+    {
+        var mockJsRuntime = new Mock<IJSRuntime>();
+        var localStorageService = new LocalStorageService(mockJsRuntime.Object);
+        var authStateProvider = new Mock<AuthenticationStateProvider>();
+        var mailService = new Mock<IMailService>();
+        var appSettings = new Mock<IOptions<AppSettings>>();
+        appSettings.Setup(x => x.Value).Returns(new AppSettings());
+
+        return new AuthService(context, localStorageService, authStateProvider.Object, mailService.Object, appSettings.Object);
+    }
+
+    [Fact]
+    public async Task GetProspectsAsync_RespectsSkipAndTake()
+    {
+        var dbName = Guid.NewGuid().ToString();
+        using var context = CreateInMemoryContext(dbName);
+        var authService = CreateAuthService(context);
+        var auditService = new AuditService(context, authService);
+        var prospectService = new ProspectService(context, authService, auditService);
+
+        for (var i = 0; i < 5; i++)
+        {
+            context.Prospects!.Add(new Prospect
+            {
+                Id = Guid.NewGuid(),
+                Name = $"Prospect {i}",
+                Modified = DateTime.UtcNow.AddDays(-i),
+                Interactions = new List<Interaction>()
+            });
+        }
+
+        await context.SaveChangesAsync();
+
+        var result = await prospectService.GetProspectsAsync(new GetProspectsParameter
+        {
+            Skip = 1,
+            Take = 2,
+            IncludeDeleted = true
+        });
+
+        Assert.True(result.Success);
+        Assert.Equal(2, result.Data.Count);
+        Assert.Equal("Prospect 1", result.Data[0].Name);
+        Assert.Equal("Prospect 2", result.Data[1].Name);
+    }
+}