Fix schema confusion when integrating EF Core with Marten

Directory.Packages.props

@@ -60,8 +60,8 @@
     <PackageVersion Include="Swashbuckle.AspNetCore" Version="6.5.0" />
     <PackageVersion Include="System.IO.Hashing" Version="10.0.3" />
     <PackageVersion Include="Vogen" Version="7.0.0" />
-    <PackageVersion Include="Weasel.EntityFrameworkCore" Version="8.9.0" />
-    <PackageVersion Include="Weasel.Postgresql" Version="8.9.0" />
+    <PackageVersion Include="Weasel.EntityFrameworkCore" Version="8.9.1" />
+    <PackageVersion Include="Weasel.Postgresql" Version="8.9.1" />
     <PackageVersion Include="WolverineFx.Marten" Version="4.2.0" />
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />

src/Marten.EntityFrameworkCore.Tests/EfCoreSchemaTests.cs

@@ -0,0 +1,129 @@
+using System;
+using System.Linq;
+using Marten.Testing.Harness;
+using Microsoft.EntityFrameworkCore;
+using Shouldly;
+using Weasel.Postgresql.Tables;
+using Xunit;
+
+namespace Marten.EntityFrameworkCore.Tests;
+
+/// <summary>
+/// Entities and DbContext for testing schema handling with EF Core integration.
+/// Reproduces https://github.com/JasperFx/marten/issues/4175
+/// </summary>
+public class EntityType
+{
+    public int Id { get; set; }
+    public string Key { get; set; } = string.Empty;
+    public string Name { get; set; } = string.Empty;
+}
+
+public class Entity
+{
+    public Guid Id { get; set; }
+    public int EntityTypeId { get; set; }
+    public bool Featured { get; set; }
+    public string InternalName { get; set; } = string.Empty;
+
+    public EntityType EntityType { get; set; } = null!;
+}
+
+/// <summary>
+/// DbContext that places entities in an explicit "test_ef_schema" schema,
+/// separate from the Marten document store schema.
+/// </summary>
+public class SeparateSchemaDbContext : DbContext
+{
+    public const string EfSchema = "test_ef_schema";
+
+    public SeparateSchemaDbContext(DbContextOptions<SeparateSchemaDbContext> options) : base(options)
+    {
+    }
+
+    public DbSet<Entity> Entities => Set<Entity>();
+    public DbSet<EntityType> EntityTypes => Set<EntityType>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.HasDefaultSchema(EfSchema);
+
+        modelBuilder.Entity<EntityType>(entity =>
+        {
+            entity.ToTable("entity_type");
+            entity.HasKey(e => e.Id);
+        });
+
+        modelBuilder.Entity<Entity>(entity =>
+        {
+            entity.ToTable("entity");
+            entity.HasKey(e => e.Id);
+            entity.HasOne(e => e.EntityType)
+                .WithMany()
+                .HasForeignKey(e => e.EntityTypeId)
+                .OnDelete(DeleteBehavior.Cascade);
+        });
+    }
+}
+
+public class EfCoreSchemaTests
+{
+    [Fact]
+    public void should_respect_ef_core_explicit_schema_and_not_move_tables_to_marten_schema()
+    {
+        // Issue #4175: When EF Core entities have an explicit schema configured,
+        // AddEntityTablesFromDbContext should NOT move those tables into Marten's schema.
+        const string martenSchema = "test_marten_schema";
+
+        using var store = DocumentStore.For(opts =>
+        {
+            opts.Connection(ConnectionSource.ConnectionString);
+            opts.DatabaseSchemaName = martenSchema;
+
+            opts.AddEntityTablesFromDbContext<SeparateSchemaDbContext>();
+        });
+
+        // Find the EF Core tables that were registered
+        var extendedObjects = store.Options.Storage.ExtendedSchemaObjects;
+
+        var entityTable = extendedObjects.OfType<Table>()
+            .FirstOrDefault(t => t.Identifier.Name == "entity");
+        var entityTypeTable = extendedObjects.OfType<Table>()
+            .FirstOrDefault(t => t.Identifier.Name == "entity_type");
+
+        entityTable.ShouldNotBeNull();
+        entityTypeTable.ShouldNotBeNull();
+
+        // These tables should remain in the EF Core schema, NOT Marten's schema
+        entityTable.Identifier.Schema.ShouldBe(SeparateSchemaDbContext.EfSchema,
+            "Entity table should stay in the EF Core schema, not be moved to Marten's schema");
+        entityTypeTable.Identifier.Schema.ShouldBe(SeparateSchemaDbContext.EfSchema,
+            "EntityType table should stay in the EF Core schema, not be moved to Marten's schema");
+    }
+
+    [Fact]
+    public void should_move_tables_without_explicit_schema_to_marten_schema()
+    {
+        // When EF Core entities do NOT have an explicit schema,
+        // they should still be moved to Marten's schema (existing behavior).
+        const string martenSchema = "test_marten_schema";
+
+        using var store = DocumentStore.For(opts =>
+        {
+            opts.Connection(ConnectionSource.ConnectionString);
+            opts.DatabaseSchemaName = martenSchema;
+
+            // TestDbContext does not set an explicit schema
+            opts.AddEntityTablesFromDbContext<TestDbContext>();
+        });
+
+        var extendedObjects = store.Options.Storage.ExtendedSchemaObjects;
+
+        var orderSummariesTable = extendedObjects.OfType<Table>()
+            .FirstOrDefault(t => t.Identifier.Name == "ef_order_summaries");
+
+        orderSummariesTable.ShouldNotBeNull();
+        orderSummariesTable.Identifier.Schema.ShouldBe(martenSchema,
+            "Tables without explicit schema should be moved to Marten's schema");
+    }
+}

src/Marten.EntityFrameworkCore/EfCoreProjectionExtensions.cs

@@ -100,9 +100,12 @@ public static void AddEntityTablesFromDbContext<TDbContext>(this StoreOptions op
         {
             var table = migrator.MapToTable(entityType);
 
-            // Move EF Core tables into the same schema as the Marten store
-            // so they participate in schema migration and cleanup together
-            if (!string.IsNullOrEmpty(schemaName) && table is Table pgTable)
+            // Only move tables to the Marten schema if the entity does NOT have an
+            // explicit schema configured in EF Core. When a user has deliberately placed
+            // entities in a separate schema (e.g., via HasDefaultSchema or ToTable("name", "schema")),
+            // that schema should be respected. See https://github.com/JasperFx/marten/issues/4175
+            var efSchema = entityType.GetSchema();
+            if (efSchema == null && !string.IsNullOrEmpty(schemaName) && table is Table pgTable)
             {
                 pgTable.MoveToSchema(schemaName);
             }