Get partition keys, container name, and JsonIdDefinition from the root entity in the hierarchy by default

src/EFCore.Cosmos/Extensions/CosmosEntityTypeExtensions.cs

@@ -196,7 +196,9 @@ public static void SetPartitionKeyPropertyName(this IMutableEntityType entityTyp
     /// <param name="entityType">The entity type.</param>
     /// <returns>The names of the partition key properties, or <see langword="null"/> if not set.</returns>
     public static IReadOnlyList<string> GetPartitionKeyPropertyNames(this IReadOnlyEntityType entityType)
-        => entityType[CosmosAnnotationNames.PartitionKeyNames] as IReadOnlyList<string> ?? Array.Empty<string>();
+        => entityType[CosmosAnnotationNames.PartitionKeyNames] as IReadOnlyList<string>
+            ?? entityType.BaseType?.GetPartitionKeyPropertyNames()
+            ?? Array.Empty<string>();
 
     /// <summary>
     ///     Sets the names of the properties that are used to store the hierarchical partition key.

src/EFCore.Cosmos/Infrastructure/Internal/CosmosModelValidator.cs

@@ -63,6 +63,13 @@ protected virtual void ValidateSharedContainerCompatibility(
                 continue;
             }
 
+            if (entityType.BaseType != null
+                && entityType.FindAnnotation(CosmosAnnotationNames.ContainerName)?.Value != null)
+            {
+                throw new InvalidOperationException(
+                    CosmosStrings.ContainerNotOnRoot(entityType.DisplayName(), entityType.BaseType.DisplayName()));
+            }
+
             var ownership = entityType.FindOwnership();
             if (ownership != null)
             {
@@ -345,6 +352,13 @@ protected virtual void ValidateKeys(
             }
             else
             {
+                if (entityType.BaseType != null
+                    && entityType.FindAnnotation(CosmosAnnotationNames.PartitionKeyNames)?.Value != null)
+                {
+                    throw new InvalidOperationException(
+                        CosmosStrings.PartitionKeyNotOnRoot(entityType.DisplayName(), entityType.BaseType.DisplayName()));
+                }
+
                 foreach (var partitionKeyPropertyName in partitionKeyPropertyNames)
                 {
                     var partitionKey = entityType.FindProperty(partitionKeyPropertyName);

src/EFCore.Cosmos/Metadata/Internal/CosmosEntityTypeExtensions.cs

@@ -29,9 +29,11 @@ public static bool IsDocumentRoot(this IReadOnlyEntityType entityType)
     /// </summary>
     /// <param name="entityType">The entity type.</param>
     public static IJsonIdDefinition? GetJsonIdDefinition(this IEntityType entityType)
-        => entityType.GetOrAddRuntimeAnnotationValue(CosmosAnnotationNames.JsonIdDefinition,
-            static e =>
-                ((CosmosModelRuntimeInitializerDependencies)e!.Model.FindRuntimeAnnotationValue(
-                    CosmosAnnotationNames.ModelDependencies)!).JsonIdDefinitionFactory.Create(e),
-            entityType);
+        => entityType.BaseType?.GetJsonIdDefinition()
+            ?? entityType.GetOrAddRuntimeAnnotationValue(
+                CosmosAnnotationNames.JsonIdDefinition,
+                static e =>
+                    ((CosmosModelRuntimeInitializerDependencies)e!.Model.FindRuntimeAnnotationValue(
+                        CosmosAnnotationNames.ModelDependencies)!).JsonIdDefinitionFactory.Create(e),
+                entityType);
 }

src/EFCore.Cosmos/Properties/CosmosStrings.resx

@@ -132,6 +132,9 @@
   <data name="ContainerContainingPropertyConflict" xml:space="preserve">
     <value>The entity type '{entityType}' is mapped to the container '{container}' but it is also configured as being contained in property '{property}'.</value>
   </data>
+  <data name="ContainerNotOnRoot" xml:space="preserve">
+    <value>An Azure Cosmos DB container name is defined on entity type '{entityType}', which inherits from '{baseEntityType}'. Container names must be defined on the root entity type of a hierarchy.</value>
+  </data>
   <data name="CosmosNotInUse" xml:space="preserve">
     <value>Cosmos-specific methods can only be used when the context is using the Cosmos provider.</value>
   </data>
@@ -289,6 +292,9 @@
   <data name="PartitionKeyBadValueType" xml:space="preserve">
     <value>The partition key value supplied for '{propertyType}' property '{entityType}.{property}' is of type '{valueType}'. Partition key values must be of a type assignable to the property.</value>
   </data>
+  <data name="PartitionKeyNotOnRoot" xml:space="preserve">
+    <value>A partition key is defined on entity type '{entityType}', which inherits from '{baseEntityType}'. Partition keys must be defined on the root entity type of a hierarchy.</value>
+  </data>
   <data name="PartitionKeyMissing" xml:space="preserve">
     <value>Unable to execute a 'ReadItem' query since the partition key value is missing. Consider using the 'WithPartitionKey' method on the query to specify partition key to use.</value>
   </data>

test/EFCore.Cosmos.FunctionalTests/Query/ReadItemPartitionKeyQueryTest.cs

@@ -375,8 +375,7 @@ protected override void OnModelCreating(ModelBuilder modelBuilder, DbContext con
             modelBuilder.Entity<SharedContainerEntity2>()
                 .ToContainer("SharedContainer")
                 .HasPartitionKey(e => e.PartitionKey);
-            modelBuilder.Entity<SharedContainerEntity2Child>()
-                .HasPartitionKey(e => e.PartitionKey);
+            modelBuilder.Entity<SharedContainerEntity2Child>();
         }
 
         public override DbContextOptionsBuilder AddOptions(DbContextOptionsBuilder builder)

test/EFCore.Cosmos.FunctionalTests/TestUtilities/CosmosTestStore.cs

@@ -616,7 +616,7 @@ public InstantiationBinding ServiceOnlyConstructorBinding
             => throw new NotImplementedException();
 
         IReadOnlyEntityType IReadOnlyEntityType.BaseType
-            => throw new NotImplementedException();
+            => null!;
 
         IReadOnlyModel IReadOnlyTypeBase.Model
             => throw new NotImplementedException();

test/EFCore.Cosmos.Tests/Infrastructure/CosmosModelValidatorTest.cs

@@ -155,6 +155,69 @@ public virtual void Detects_missing_partition_key_on_first_type()
         VerifyError(CosmosStrings.NoPartitionKey(nameof(Customer), "", nameof(Order), "PartitionId", "Orders"), modelBuilder);
     }
 
+    [ConditionalFact] // Issue #34176
+    public virtual void Partition_keys_do_not_need_to_be_explicitly_configured_on_non_root_types()
+    {
+        var modelBuilder = CreateConventionModelBuilder();
+
+        modelBuilder.Entity<A>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<B>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<C>();
+        modelBuilder.Entity<D>();
+        modelBuilder.Entity<F>();
+
+        Validate(modelBuilder);
+    }
+
+    [ConditionalFact] // Issue #34176
+    public virtual void Partition_keys_can_only_be_defined_on_the_root_of_a_hierarchy()
+    {
+        var modelBuilder = CreateConventionModelBuilder();
+
+        modelBuilder.Entity<A>(
+            b =>
+            {
+                b.HasPartitionKey(e => e.P0);
+                b.ToContainer("As");
+                b.HasKey(e => new { e.P0, e.P1 });
+            });
+
+        modelBuilder.Entity<B>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<C>().ToContainer("As");
+        modelBuilder.Entity<D>().HasPartitionKey(e => e.P1).ToContainer("As");
+        modelBuilder.Entity<F>().ToContainer("As");
+
+        VerifyError(CosmosStrings.PartitionKeyNotOnRoot(nameof(D), nameof(A)), modelBuilder);
+    }
+
+    [ConditionalFact] // Issue #34176
+    public virtual void Container_does_not_need_to_be_explicitly_configured_on_non_root_types()
+    {
+        var modelBuilder = CreateConventionModelBuilder();
+
+        modelBuilder.Entity<A>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<B>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<C>();
+        modelBuilder.Entity<D>();
+        modelBuilder.Entity<F>();
+
+        Validate(modelBuilder);
+    }
+
+    [ConditionalFact] // Issue #34176
+    public virtual void Container_can_only_be_defined_on_the_root_of_a_hierarchy()
+    {
+        var modelBuilder = CreateConventionModelBuilder();
+
+        modelBuilder.Entity<A>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<B>().HasPartitionKey(e => e.P0).ToContainer("As");
+        modelBuilder.Entity<C>();
+        modelBuilder.Entity<D>().ToContainer("Ds");
+        modelBuilder.Entity<F>();
+
+        VerifyError(CosmosStrings.ContainerNotOnRoot(nameof(D), nameof(A)), modelBuilder);
+    }
+
     [ConditionalFact]
     public virtual void Detects_missing_partition_keys_one_last_type()
     {