fix: typo in references for multitenancy

fix: `null: true` when attr isn't on all resources for a table

lib/migration_generator/migration_generator.ex

@@ -117,6 +117,7 @@ defmodule AshPostgres.MigrationGenerator do
       {primary_key, identities} = merge_primary_keys(existing_snapshot, snapshots)
 
       attributes = Enum.flat_map(snapshots, & &1.attributes)
+      count = Enum.count(snapshots)
 
       snapshot_identities =
         snapshots
@@ -125,7 +126,7 @@ defmodule AshPostgres.MigrationGenerator do
 
       new_snapshot = %{
         snapshot
-        | attributes: merge_attributes(attributes, snapshot.table),
+        | attributes: merge_attributes(attributes, snapshot.table, count),
           identities: snapshot_identities
       }
 
@@ -167,19 +168,23 @@ defmodule AshPostgres.MigrationGenerator do
     end)
   end
 
-  defp merge_attributes(attributes, table) do
+  defp merge_attributes(attributes, table, count) do
     attributes
     |> Enum.group_by(& &1.name)
     |> Enum.map(fn
       {_name, [attribute]} ->
-        attribute
+        if count > 1 do
+          %{attribute | allow_nil?: true}
+        else
+          attribute
+        end
 
       {name, attributes} ->
         %{
           name: name,
           type: merge_types(Enum.map(attributes, & &1.type), name, table),
           default: merge_defaults(Enum.map(attributes, & &1.default)),
-          allow_nil?: Enum.any?(attributes, & &1.allow_nil?),
+          allow_nil?: Enum.any?(attributes, & &1.allow_nil?) || Enum.count(attributes) < count,
           references: merge_references(Enum.map(attributes, & &1.references), name, table),
           primary_key?: false
         }

lib/migration_generator/operation.ex

@@ -268,7 +268,7 @@ defmodule AshPostgres.MigrationGenerator.Operation do
              }
            }
          ) do
-      "references(:#{table}, type: #{inspect(type)}, column: #{inspect(destination_field)}, prefix(): \"public\")"
+      "references(:#{table}, type: #{inspect(type)}, column: #{inspect(destination_field)}, prefix: \"public\")"
     end
 
     defp reference(

test/migration_generator_test.exs

@@ -348,6 +348,39 @@ defmodule AshPostgres.MigrationGeneratorTest do
       assert File.read!(file2) =~
                ~S[add :foobar, :text]
     end
+
+    test "when an attribute exists only on some of the resources that use the same table, it isn't marked as null: false" do
+      defposts do
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:title, :string)
+          attribute(:example, :string, allow_nil?: false)
+        end
+      end
+
+      defposts Post2 do
+        attributes do
+          uuid_primary_key(:id)
+        end
+      end
+
+      defapi([Post, Post2])
+
+      AshPostgres.MigrationGenerator.generate(Api,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false
+      )
+
+      assert [_file1, file2] =
+               Enum.sort(Path.wildcard("test_migration_path/**/*_migrate_resources*.exs"))
+
+      assert File.read!(file2) =~
+               ~S[add :example, :text] <> "\n"
+
+      refute File.read!(file2) =~ ~S[null: false]
+    end
   end
 
   describe "auto incrementing integer, when generated" do