fix FK reference from multi tenanted document to single tenanted document

Author: aare-arnold

src/DocumentDbTests/ForeignKeys/configuring_foreign_key_fields.cs

@@ -1,8 +1,10 @@
 using System;
-using JasperFx.Core;
+using System.Linq;
 using JasperFx.Core.Reflection;
 using Marten;
 using Marten.Schema;
+using Marten.Storage;
+using Marten.Storage.Metadata;
 using Marten.Testing.Harness;
 using Shouldly;
 using Xunit;
@@ -66,6 +68,75 @@ public void should_allow_foreign_key_on_id_field()
             .ShouldContain(x => x.ColumnNames[0] == "id");
     }
 
+    [Fact]
+    public void should_not_include_tenant_id_in_foreign_key_from_tenanted_doc_to_not_tenanted_doc()
+    {
+        var store = StoreOptions(_ =>
+        {
+            _.MultiTenantedWithSingleServer(ConnectionSource.ConnectionString, c =>
+            {
+                c.WithTenants("tenant1").InDatabaseNamed("postgres");
+            });
+
+            _.Schema.For<Foo>()
+                .SingleTenanted()
+                .Identity(x => x.FooId);
+            _.Schema.For<Bar>()
+                .MultiTenanted()
+                .Identity(x => x.BarId)
+                .ForeignKey<Foo>(x => x.FooId);
+        });
+
+        var mapping = store.Options.Storage.MappingFor(typeof(Bar));
+        new DocumentTable(mapping).ForeignKeys.Single().ColumnNames.ShouldNotContain(TenantIdColumn.Name);
+    }
+
+    [Fact]
+    public void should_include_tenant_id_in_foreign_key_between_tenanted_docs()
+    {
+        var store = StoreOptions(_ =>
+        {
+            _.MultiTenantedWithSingleServer(ConnectionSource.ConnectionString, c =>
+            {
+                c.WithTenants("tenant1").InDatabaseNamed("postgres");
+            });
+
+            _.Schema.For<Foo>()
+                .MultiTenanted()
+                .Identity(x => x.FooId);
+            _.Schema.For<Bar>()
+                .MultiTenanted()
+                .Identity(x => x.BarId)
+                .ForeignKey<Foo>(x => x.FooId);
+        });
+
+        var mapping = store.Options.Storage.MappingFor(typeof(Bar));
+        new DocumentTable(mapping).ForeignKeys.Single().ColumnNames.ShouldContain(TenantIdColumn.Name);
+    }
+
+    [Fact]
+    public void should_not_include_tenant_id_between_single_tenanted_docs()
+    {
+        var store = StoreOptions(_ =>
+        {
+            _.MultiTenantedWithSingleServer(ConnectionSource.ConnectionString, c =>
+            {
+                c.WithTenants("tenant1").InDatabaseNamed("postgres");
+            });
+
+            _.Schema.For<Foo>()
+                .SingleTenanted()
+                .Identity(x => x.FooId);
+            _.Schema.For<Bar>()
+                .SingleTenanted()
+                .Identity(x => x.BarId)
+                .ForeignKey<Foo>(x => x.FooId);
+        });
+
+        var mapping = store.Options.Storage.MappingFor(typeof(Bar));
+        new DocumentTable(mapping).ForeignKeys.Single().ColumnNames.ShouldNotContain(TenantIdColumn.Name);
+    }
+
     #region sample_issue-with-fk-attribute
     public class Issue
     {
@@ -138,4 +209,10 @@ public class FooExtra
     {
         public Guid FooId { get; set; }
     }
+
+    public class Bar
+    {
+        public Guid BarId { get; set; }
+        public Guid FooId { get; set; }
+    }
 }

src/Marten/Schema/DocumentMapping.cs

@@ -971,8 +971,8 @@ internal static class ForeignKeyExtensions
 {
     public static void TryMoveTenantIdFirst(this ForeignKey foreignKey, DocumentMapping mapping)
     {
-        // Guard clause, do nothing if this document is not tenanted
-        if (mapping.TenancyStyle == TenancyStyle.Single) return;
+        // Guard clause, do nothing if this document is not tenanted or foreign key doesn't contain tenant id
+        if (mapping.TenancyStyle == TenancyStyle.Single || foreignKey.ColumnNames.Any(x => x != TenantIdColumn.Name)) return;
 
         foreignKey.ColumnNames = new string[] { TenantIdColumn.Name }
             .Concat(foreignKey.ColumnNames.Where(x => x != TenantIdColumn.Name)).ToArray();