RevEng: Scaffold Many-To-Many join table #25544

smitpatel · 2021-08-16T21:31:27Z

No description provided.

src/EFCore.Design/Scaffolding/Internal/CSharpDbContextGenerator.cs

bricelam · 2021-08-16T22:55:56Z

src/EFCore.Design/Scaffolding/Internal/CSharpDbContextGenerator.cs

@@ -864,5 +1138,31 @@ private void GenerateAnnotations(IAnnotatable annotatable, Dictionary<string, IA
            lines.AddRange(annotations.Values.Select(
                a => $".HasAnnotation({_code.Literal(a.Name)}, {_code.UnknownLiteral(a.Value)})"));
        }
+
+        internal static bool IsManyToManyJoinEntityType(IEntityType entityType)


There's no concept of a join/association type in the model? It's just defined by its structure? Kinda makes this code tedious. Should this be an extension method in the core assembly?

There is implicit join entity type but in this case the entity type is configured explicitly so it is not same as what we create by convention in definition.

src/EFCore.Design/Scaffolding/Internal/RelationalScaffoldingModelFactory.cs

bricelam · 2021-08-16T23:06:59Z

test/EFCore.Design.Tests/Scaffolding/Internal/CSharpEntityTypeGeneratorTest.cs

+                    .UsingEntity<Dictionary<string, object>>(
+                        ""BlogPost"",
+                        l => l.HasOne<Post>().WithMany().HasForeignKey(""BlogsId""),
+                        r => r.HasOne<Blog>().WithMany().HasForeignKey(""PostsId""),
+                        j =>
+                        {
+                            j.HasKey(""BlogsId"", ""PostsId"");
+
+                            j.ToTable(""BlogPost"");
+
+                            j.HasIndex(new[] { ""PostsId"" }, ""IX_BlogPost_PostsId"");
+                        });


This seems pretty verbose. Isn't all this done by convention?

Fk currently has issue about not accounting for all facets. To err on the side of producing correct code, I just printed it out.

Index is necessary even with data-annotation since no concrete class.

Key doesn't seem to have deterministic ordering in what would be PK. @AndriySvyryd would know. It is not easy to figure convention PK like Id.

Table call may be removed, should we remove it when it has same name as entity type?

I ran generation on EF6 created M2M table,

It needs to print FKs because constraint has name.

Table goes through pluralizer so doesn't match entity type name.

2 indexes

It even generates properties since column names are different than property names.

The PK is based on the FK order, which is based on the property names. I don't mind the redundant configuration for PK, but we could avoid the ToTable call.

I filed #25547

Specifically want to play more with the feature to see different patterns and facets. Perhaps @ajcvickers' new feature testing thing. Outside of our limited testing, I only tested with EF6 generated schema.

src/EFCore.Design/Scaffolding/Internal/CSharpDbContextGenerator.cs

src/EFCore.Design/Scaffolding/Internal/CSharpEntityTypeGenerator.cs

src/EFCore.Design/Scaffolding/Internal/RelationalScaffoldingModelFactory.cs

ErikEJ · 2021-08-17T06:01:28Z

This is a fix for #22475

smitpatel requested a review from a team August 16, 2021 21:31