Enable working with lazy loading proxies SN-776

src/Saritasa.NetForge/Controls/CustomFields/NavigationCollectionField.razor.cs

@@ -1,6 +1,9 @@
 using Microsoft.AspNetCore.Components;
 using Saritasa.NetForge.Domain.UseCases.Interfaces;
 using Saritasa.NetForge.Domain.UseCases.Metadata.GetEntityById;
+using Saritasa.NetForge.Infrastructure.EfCore.Extensions;
+using Saritasa.NetForge.Infrastructure.EfCore.Services;
+using Saritasa.NetForge.Infrastructure.Helpers;
 
 namespace Saritasa.NetForge.Controls.CustomFields;
 
@@ -24,7 +27,6 @@ public IEnumerable<T> PropertyValue
 
     private IEnumerable<T> NavigationInstances { get; set; } = null!;
 
-
     private GetEntityDto EntityMetadata { get; set; } = null!;
 
     /// <inheritdoc />
@@ -37,7 +39,14 @@ protected override async Task OnInitializedAsync()
         NavigationInstances = Service
             .GetQuery(entityType)
             .Cast<T>()
-            .OrderBy(instance => instance);
+            .OrderBy(instance => instance).ToList();
+
+        // In case of lazy loading - convert proxies to POCO instances.
+        if (NavigationInstances.Any() && NavigationInstances.First()!.GetType().IsLazyLoadingProxy())
+        {
+            NavigationInstances = NavigationInstances
+                .Select(instance => ProxyToPocoConverter.ConvertProxyToPoco(instance)).Cast<T>();
+        }
 
         EntityMetadata = await EntityService.GetEntityByTypeAsync(entityType, CancellationToken.None);
     }

src/Saritasa.NetForge/Domain/Extensions/CloneExtensions.cs

@@ -33,7 +33,13 @@ public static class CloneExtensions
 
         var serializeSettings = new JsonSerializerSettings
         {
-            ReferenceLoopHandling = ReferenceLoopHandling.Ignore
+            ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
+
+            // Ignore errors during serialization (in case of shadow properties in LazyLoadingProxies).
+            Error = (serializer, err) =>
+            {
+                err.ErrorContext.Handled = true;
+            }
         };
 
         serializeSettings.Converters.Add(new DecimalJsonConverter());

src/Saritasa.NetForge/Infrastructure/EfCore/Extensions/EntityProxyExtensions.cs

@@ -0,0 +1,40 @@
+namespace Saritasa.NetForge.Infrastructure.EfCore.Extensions;
+
+/// <summary>
+/// Contains extension methods for entity proxies.
+/// </summary>
+public static class EntityProxyExtensions
+{
+    private const string CastleProxiesNamespace = "Castle.Proxies";
+
+    /// <summary>
+    /// Checks if the given type is a lazy loading proxy.
+    /// </summary>
+    /// <param name="type">The type to check.</param>
+    /// <returns>True if the type is a lazy loading proxy, otherwise false.</returns>
+    public static bool IsLazyLoadingProxy(this Type type)
+    {
+        var baseType = type.BaseType;
+
+        // Check if the type is a proxy type generated by EF Core for lazy loading.
+        return baseType != null && type.Namespace == CastleProxiesNamespace;
+    }
+
+    /// <summary>
+    /// Gets the POCO type of the entity.
+    /// </summary>
+    /// <param name="entity">Entity instance.</param>
+    /// <returns>The POCO type if the entity is a lazy loading proxy.</returns>
+    /// <exception cref="InvalidOperationException">Throws if the provided entity is not a lazy loading proxy.</exception>
+    public static Type GetPocoType(this object entity)
+    {
+        var entityType = entity.GetType();
+
+        if (!entityType.IsLazyLoadingProxy())
+        {
+            throw new InvalidOperationException($"The provided entity of type {entityType.Name} is not a lazy loading proxy.");
+        }
+
+        return entityType.BaseType!;
+    }
+}

src/Saritasa.NetForge/Infrastructure/EfCore/Services/EfCoreDataService.cs

@@ -117,6 +117,13 @@ private DbContext GetDbContextThatContainsEntity(Type clrType)
                 continue;
             }
 
+            // Check if the entity type is a proxy type generated by EF Core for lazy loading.
+            // If it is, get the actual type to be able to work with it.
+            if (clrType.IsLazyLoadingProxy())
+            {
+                clrType = clrType.BaseType!;
+            }
+
             var dbContext = (DbContext)dbContextService;
             var entityType = dbContext.Model.FindEntityType(clrType);
 

src/Saritasa.NetForge/Infrastructure/EfCore/Services/ProxyToPocoConverter.cs

@@ -0,0 +1,112 @@
+using System.Collections;
+using Saritasa.NetForge.Infrastructure.EfCore.Extensions;
+
+namespace Saritasa.NetForge.Infrastructure.EfCore.Services;
+
+/// <summary>
+/// Convert entities with lazy loading proxies to POCO entities.
+/// </summary>
+public static class ProxyToPocoConverter
+{
+    /// <summary>
+    /// Converts a proxy entity to a POCO entity.
+    /// </summary>
+    /// <param name="source">The source proxy entity.</param>
+    /// <param name="navigationPropertyNames">The list of navigation property names.</param>
+    /// <returns>The POCO entity.</returns>
+    public static object? ConvertProxyToPoco(object? source, IList<string>? navigationPropertyNames = null)
+    {
+        switch (source)
+        {
+            case null:
+                return default;
+
+            // Sometimes the source is a collection of proxy entities.
+            case IEnumerable<object> sourceCollection:
+                {
+                    var sourceType = source.GetType();
+
+                    // Get the item type of the collection to avoid boxing issues.
+                    var itemType = sourceType.GetGenericArguments().FirstOrDefault() ?? typeof(object);
+                    var pocoCollectionType = typeof(List<>).MakeGenericType(itemType);
+                    var pocoCollection = (IList)Activator.CreateInstance(pocoCollectionType)!;
+
+                    foreach (var item in sourceCollection)
+                    {
+                        pocoCollection.Add(ConvertProxyToPoco(item));
+                    }
+                    return pocoCollection;
+                }
+        }
+
+        var entityType = source.GetPocoType();
+
+        // Create new instance of the POCO entity.
+        var pocoInstance = Activator.CreateInstance(entityType)!;
+
+        // Copy the properties from the proxy to the POCO.
+        foreach (var property in entityType.GetProperties())
+        {
+            // Exclude the navigation properties because they are the proxies as well.
+            if (navigationPropertyNames != null && navigationPropertyNames.Contains(property.Name))
+            {
+                continue;
+            }
+
+            // Exclude indexers, read-only and write-only properties.
+            if (!property.CanWrite || !property.CanRead || property.GetIndexParameters().Length > 0)
+            {
+                continue;
+            }
+
+            try
+            {
+                var value = property.GetValue(source);
+
+                // Skip the property if it is a proxy.
+                if (value != null && value.GetType().IsLazyLoadingProxy())
+                {
+                    continue;
+                }
+
+                // Check if the property is a collection of proxy entities.
+                if (value is IEnumerable<object> collection)
+                {
+                    var firstItem = collection.FirstOrDefault();
+                    if (firstItem != null && firstItem.GetType().IsLazyLoadingProxy())
+                    {
+                        continue;
+                    }
+                }
+
+                property.SetValue(pocoInstance, value);
+            }
+            catch
+            {
+                // Skip the property if it cannot be copied.
+            }
+        }
+
+        if (navigationPropertyNames == null)
+        {
+            return pocoInstance;
+        }
+
+        // Do the same for the navigation properties recursively because they can be proxies as well.
+        foreach (var navigationName in navigationPropertyNames)
+        {
+            var property = source.GetType().GetProperty(navigationName);
+            var propertyValue = property?.GetValue(source);
+
+            if (property == null)
+            {
+                continue;
+            }
+
+            var navigationPoco = ConvertProxyToPoco(propertyValue);
+            entityType.GetProperty(navigationName)?.SetValue(pocoInstance, navigationPoco);
+        }
+
+        return pocoInstance;
+    }
+}

src/Saritasa.NetForge/MVVM/ViewModels/EditEntity/EditEntityViewModel.cs

@@ -8,6 +8,8 @@
 using Saritasa.NetForge.Domain.UseCases.Interfaces;
 using Saritasa.NetForge.Domain.UseCases.Metadata.GetEntityById;
 using Saritasa.NetForge.Infrastructure.Abstractions.Interfaces;
+using Saritasa.NetForge.Infrastructure.EfCore.Extensions;
+using Saritasa.NetForge.Infrastructure.EfCore.Services;
 
 namespace Saritasa.NetForge.MVVM.ViewModels.EditEntity;
 
@@ -83,11 +85,23 @@ public override async Task LoadAsync(CancellationToken cancellationToken)
 
             var includedNavigationNames = Model.Properties
                 .Where(property => property is NavigationMetadataDto)
-                .Select(property => property.Name);
+                .Select(property => property.Name).ToList();
 
             Model.EntityInstance = await dataService
                 .GetInstanceAsync(instancePrimaryKey, Model.ClrType!, includedNavigationNames, CancellationToken);
 
+            var instanceType = Model.EntityInstance.GetType();
+
+            // Check if the entity type is a proxy type generated by EF Core for lazy loading and use the POCO type
+            // instead.
+            // Proxy types raise serialization issues when we try to serialize it to JSON.
+            if (instanceType.IsLazyLoadingProxy())
+            {
+                var pocoInstance = ProxyToPocoConverter.ConvertProxyToPoco(Model.EntityInstance, includedNavigationNames);
+                Model.EntityInstance = pocoInstance;
+            }
+
+            // We have to keep the original entity to work with navigation properties.
             Model.OriginalEntityInstance = Model.EntityInstance.CloneJson();
 
             FieldErrorModels = Model.Properties