Refactor how access for parent reference is set

See #120

+semver:breaking

Author: hazzik

src/FluentNHibernate.Testing/DomainModel/Mapping/ComponentElementPartTester.cs

@@ -30,7 +30,7 @@ public void CanSetParentReferenceAccess()
                         .Component(c =>
                         {
                             c.Map(x => x.Name);
-                            c.ParentReference(x => x.MyParent, FluentNHibernate.Mapping.Access.BackField);
+                            c.ParentReference(x => x.MyParent, x => x.Access.BackingField());
                         }))
                 .Element("class/bag/composite-element/parent").Exists()
                 .HasAttribute("name", "MyParent")

src/FluentNHibernate.Testing/DomainModel/Mapping/ComponentPartTester.cs

@@ -27,7 +27,7 @@ public void ComponentCanSetParentReferenceAccessStrategy()
                     m.Component(x => x.Component, c =>
                     {
                         c.Map(x => x.Name);
-                        c.ParentReference(x => x.MyParent, FluentNHibernate.Mapping.Access.BackField);
+                        c.ParentReference(x => x.MyParent, x => x.Access.BackingField());
                     }))
                 .Element("class/component/parent").ShouldBeInParentAtPosition(0)
                 .HasAttribute("name", "MyParent")

src/FluentNHibernate/Mapping/ComponentPartBase.cs

@@ -59,34 +59,36 @@ public AccessStrategyBuilder<TBuilder> Access
         /// </example>
         public TBuilder ParentReference(Expression<Func<TEntity, object>> expression)
         {
-            var property = expression.ToMember();
-            return ParentReference(property, MemberAccessResolver.Resolve(property));
+            return ParentReference(expression, null);
         }
 
         /// <summary>
         /// Specify a parent reference for this component
         /// </summary>
         /// <param name="expression">Parent property</param>
-        /// <param name="access">Access to parent property</param>
+        /// <param name="customMapping">Additional settings for the parent reference property</param>
         /// <example>
         /// ParentReference(x => x.Parent, Access.Backfield);
         /// </example>
-        public TBuilder ParentReference(Expression<Func<TEntity, object>> expression, Access access)
+        public TBuilder ParentReference(Expression<Func<TEntity, object>> expression, Action<ParentPropertyPart> customMapping)
         {
-            return ParentReference(expression.ToMember(), access);
+            return ParentReference(expression.ToMember(), customMapping);
         }
 
-        TBuilder ParentReference(Member property, Access access)
+        TBuilder ParentReference(Member property, Action<ParentPropertyPart> customMapping)
         {
             var parentMapping = new ParentMapping
             {
                 ContainingEntityType = typeof(TEntity)
             };
             parentMapping.Set(x => x.Name, Layer.Defaults, property.Name);
 
-            if (access != Mapping.Access.Property && access != Mapping.Access.Unset)
-                parentMapping.Set(x => x.Access, Layer.Defaults, access.ToString());
-            
+            var defaultAccess = MemberAccessResolver.Resolve(property);
+            if (defaultAccess != Mapping.Access.Property && defaultAccess != Mapping.Access.Unset)
+                parentMapping.Set(x => x.Access, Layer.Defaults, defaultAccess.ToString());
+
+            customMapping?.Invoke(new ParentPropertyPart(parentMapping));
+
             attributes.Set("Parent", Layer.Defaults, parentMapping);
 
             return (TBuilder)this;

src/FluentNHibernate/Mapping/CompositeElementPart.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
-using System.Reflection;
 using FluentNHibernate.Mapping.Providers;
 using FluentNHibernate.MappingModel;
 using FluentNHibernate.MappingModel.Collections;
@@ -118,32 +117,34 @@ protected virtual ManyToOnePart<TOther> References<TOther>(Member property, stri
         /// <returns>Component being mapped</returns>
         public void ParentReference(Expression<Func<T, object>> expression)
         {
-            var property = expression.ToMember();
-            ParentReference(property, MemberAccessResolver.Resolve(property));
+            ParentReference(expression, null);
         }
 
         /// <summary>
         /// Maps a property of the component class as a reference back to the containing entity
         /// </summary>
         /// <param name="expression">Parent reference property</param>
-        /// <param name="access">Access to parent reference property</param>
+        /// <param name="customMapping">Additional settings for the parent reference property</param>
         /// <returns>Component being mapped</returns>
-        public void ParentReference(Expression<Func<T, object>> expression, Access access)
+        public void ParentReference(Expression<Func<T, object>> expression, Action<ParentPropertyPart> customMapping)
         {
-            ParentReference(expression.ToMember(), access);
+            ParentReference(expression.ToMember(), customMapping);
         }
 
-        void ParentReference(Member property, Access access)
+        void ParentReference(Member property, Action<ParentPropertyPart> customMapping)
         {
             var parentMapping = new ParentMapping
             {
                 ContainingEntityType = entity
             };
             parentMapping.Set(x => x.Name, Layer.Defaults, property.Name);
 
+            var access = MemberAccessResolver.Resolve(property);
             if (access != Access.Property && access != Access.Unset)
                 parentMapping.Set(x => x.Access, Layer.Defaults, access.ToString());
 
+            customMapping?.Invoke(new ParentPropertyPart(parentMapping));
+
             attributes.Set("Parent", Layer.Defaults, parentMapping);
         }
 

src/FluentNHibernate/Mapping/ParentPropertyPart.cs

@@ -0,0 +1,15 @@
+using FluentNHibernate.MappingModel;
+
+namespace FluentNHibernate.Mapping
+{
+    public class ParentPropertyPart
+    {
+        public ParentPropertyPart(ParentMapping mapping)
+        {
+            Access = new AccessStrategyBuilder<ParentPropertyPart>(this,
+                value => mapping.Set(x => x.Access, Layer.UserSupplied, value));
+        }
+
+        public AccessStrategyBuilder<ParentPropertyPart> Access { get; }
+    }
+}