Enhance inverse navigation handling in GraphEntityCollector and NavigationMetadata

Author: fabien.menager

src/PhenX.EntityFrameworkCore.BulkInsert/Graph/GraphEntityCollector.cs

@@ -1,5 +1,4 @@
 using System.Collections;
-using System.Reflection;
 
 using Microsoft.EntityFrameworkCore;
 
@@ -146,29 +145,18 @@ private void CollectEntity(object? entity, int depth)
 
     private static void SetInverseNavigation(object parentEntity, object childEntity, NavigationMetadata navigation)
     {
-        // For one-to-many navigations, find and set the inverse navigation property
+        // For one-to-many navigations, set the inverse navigation property
         // (e.g., if Blog.Posts is the navigation, set Post.Blog = blog)
-        var nav = navigation.Navigation;
-        if (nav is not Microsoft.EntityFrameworkCore.Metadata.INavigation regularNav)
+        if (!navigation.HasInverseSetter)
         {
             return;
         }
 
-        var inverse = regularNav.Inverse;
-        if (inverse == null)
+        // Check if the inverse navigation is already set
+        var currentValue = navigation.GetInverseValue(childEntity);
+        if (currentValue == null)
         {
-            return;
-        }
-
-        // Set the inverse navigation property on the child
-        var inversePropertyInfo = childEntity.GetType().GetProperty(inverse.Name, BindingFlags.Public | BindingFlags.Instance);
-        if (inversePropertyInfo != null && inversePropertyInfo.CanWrite)
-        {
-            var currentValue = inversePropertyInfo.GetValue(childEntity);
-            if (currentValue == null)
-            {
-                inversePropertyInfo.SetValue(childEntity, parentEntity);
-            }
+            navigation.SetInverseValue(childEntity, parentEntity);
         }
     }
 }

src/PhenX.EntityFrameworkCore.BulkInsert/Metadata/NavigationMetadata.cs

@@ -24,6 +24,21 @@ public NavigationMetadata(INavigationBase navigation)
 
         _getter = PropertyAccessor.CreateGetter(propertyInfo);
 
+        // Build inverse navigation metadata if available
+        if (navigation is INavigation { Inverse: not null } regularNav)
+        {
+            var inverse = regularNav.Inverse;
+            var inversePropertyInfo = inverse.DeclaringEntityType.ClrType.GetProperty(
+                inverse.Name,
+                BindingFlags.Public | BindingFlags.Instance);
+
+            if (inversePropertyInfo != null && inversePropertyInfo.CanWrite)
+            {
+                _inverseGetter = PropertyAccessor.CreateGetter(inversePropertyInfo);
+                _inverseSetter = PropertyAccessor.CreateSetter(inversePropertyInfo);
+            }
+        }
+
         if (navigation is ISkipNavigation skipNavigation)
         {
             IsManyToMany = true;
@@ -40,6 +55,8 @@ public NavigationMetadata(INavigationBase navigation)
     }
 
     private readonly Func<object, object?> _getter;
+    private readonly Func<object, object?>? _inverseGetter;
+    private readonly Action<object, object?>? _inverseSetter;
 
     /// <summary>
     /// The underlying EF Core navigation.
@@ -91,6 +108,23 @@ public NavigationMetadata(INavigationBase navigation)
     /// </summary>
     public object? GetValue(object entity) => _getter.Invoke(entity);
 
+    /// <summary>
+    /// Gets the value of the inverse navigation property from the entity using an optimized getter.
+    /// Returns null if there is no inverse navigation.
+    /// </summary>
+    public object? GetInverseValue(object entity) => _inverseGetter?.Invoke(entity);
+
+    /// <summary>
+    /// Sets the value of the inverse navigation property on the entity using an optimized setter.
+    /// Does nothing if there is no inverse navigation.
+    /// </summary>
+    public void SetInverseValue(object entity, object? value) => _inverseSetter?.Invoke(entity, value);
+
+    /// <summary>
+    /// Returns true if this navigation has an inverse navigation with a setter.
+    /// </summary>
+    public bool HasInverseSetter => _inverseSetter != null;
+
     public override string ToString()
     {
         var relationshipType = IsManyToMany ? "ManyToMany" : (IsCollection ? "OneToMany" : "OneToOne");

src/PhenX.EntityFrameworkCore.BulkInsert/Metadata/PropertyAccessor.cs

@@ -86,6 +86,34 @@ internal static class PropertyAccessor
         return Expression.Lambda<Func<object, object?>>(finalExpression, instanceParam).Compile();
     }
 
+    public static Action<object, object?> CreateSetter(PropertyInfo propertyInfo)
+    {
+        ArgumentNullException.ThrowIfNull(propertyInfo);
+
+        if (!propertyInfo.CanWrite)
+        {
+            throw new ArgumentException($"Property '{propertyInfo.Name}' is not writable", nameof(propertyInfo));
+        }
+
+        // (instance, value) => { }
+        var instanceParam = Expression.Parameter(typeof(object), "instance");
+        var valueParam = Expression.Parameter(typeof(object), "value");
+
+        var propDeclaringType = propertyInfo.DeclaringType!;
+
+        // Convert object to the declaring type
+        var typedInstance = GetTypedInstance(propDeclaringType, instanceParam);
+
+        // Convert value to property type (both value types and reference types need conversion from object)
+        var typedValue = Expression.Convert(valueParam, propertyInfo.PropertyType);
+
+        // ((TEntity)instance).Property = (TProperty)value
+        var propertyAccess = Expression.Property(typedInstance, propertyInfo);
+        var assignment = Expression.Assign(propertyAccess, typedValue);
+
+        return Expression.Lambda<Action<object, object?>>(assignment, instanceParam, valueParam).Compile();
+    }
+
     private static UnaryExpression GetTypedInstance(Type propDeclaringType, ParameterExpression instanceParam)
     {
         return propDeclaringType.IsValueType