feat: Add support for nulls_distinct in custom indexes

.formatter.exs

@@ -21,6 +21,7 @@ spark_locals_without_parens = [
   migration_ignore_attributes: 1,
   migration_types: 1,
   name: 1,
+  nulls_distinct: 1,
   on_delete: 1,
   on_update: 1,
   polymorphic?: 1,

documentation/dsls/DSL:-AshPostgres.DataLayer.cheatmd

@@ -507,6 +507,26 @@ index ["column", "column2"], unique: true, where: "thing = TRUE"
   </td>
 </tr>
 
+<tr>
+  <td style="text-align: left">
+    <a id="postgres-custom_indexes-index-nulls_distinct" href="#postgres-custom_indexes-index-nulls_distinct">
+      <span style="font-family: Inconsolata, Menlo, Courier, monospace;">
+        nulls_distinct
+      </span>
+    </a>
+
+  </td>
+  <td style="text-align: left">
+    <code class="inline">boolean</code>
+  </td>
+  <td style="text-align: left">
+
+  </td>
+  <td style="text-align: left" colspan=2>
+    indicates whether the index should treat nil values as distinct or not.
+  </td>
+</tr>
+
 <tr>
   <td style="text-align: left">
     <a id="postgres-custom_indexes-index-using" href="#postgres-custom_indexes-index-using">

lib/custom_index.ex

@@ -6,6 +6,7 @@ defmodule AshPostgres.CustomIndex do
     :name,
     :unique,
     :concurrently,
+    :nulls_distinct,
     :using,
     :prefix,
     :where,
@@ -36,6 +37,10 @@ defmodule AshPostgres.CustomIndex do
       doc: "indicates whether the index should be created/dropped concurrently.",
       default: false
     ],
+    nulls_distinct: [
+      type: :boolean,
+      doc: "indicates whether the index should treat nil values as distinct or not."
+    ],
     using: [
       type: :string,
       doc: "configures the index type."

lib/migration_generator/operation.ex

@@ -36,6 +36,12 @@ defmodule AshPostgres.MigrationGenerator.Operation do
       end
     end
 
+    def non_nullable_option(key, value) do
+      if not is_nil(value) do
+        "#{as_atom(key)}: #{inspect(value)}"
+      end
+    end
+
     def on_delete(%{on_delete: on_delete}) when on_delete in [:delete, :nilify] do
       "on_delete: :#{on_delete}_all"
     end
@@ -826,6 +832,7 @@ defmodule AshPostgres.MigrationGenerator.Operation do
           option(:name, index.name),
           option(:unique, index.unique),
           option(:concurrently, index.concurrently),
+          non_nullable_option(:nulls_distinct, index.nulls_distinct),
           option(:using, index.using),
           option(:prefix, index.prefix),
           option(:where, index.where),
@@ -937,6 +944,7 @@ defmodule AshPostgres.MigrationGenerator.Operation do
           option(:name, index.name),
           option(:unique, index.unique),
           option(:concurrently, index.concurrently),
+          non_nullable_option(:nulls_distinct, index[:nulls_distinct]),
           option(:using, index.using),
           option(:prefix, index.prefix),
           option(:where, index.where),

test/migration_generator_test.exs

@@ -298,6 +298,48 @@ defmodule AshPostgres.MigrationGeneratorTest do
     end
   end
 
+  describe "custom_indexes with `nulls_distinct: false`" do
+    setup do
+      on_exit(fn ->
+        File.rm_rf!("test_snapshots_path")
+        File.rm_rf!("test_migration_path")
+      end)
+
+      defposts do
+        postgres do
+          custom_indexes do
+            # need one without any opts
+            index([:title], unique: true, nulls_distinct: false)
+          end
+        end
+
+        attributes do
+          uuid_primary_key(:id)
+          attribute(:title, :string)
+        end
+      end
+
+      defapi([Post])
+      Mix.shell(Mix.Shell.Process)
+
+      AshPostgres.MigrationGenerator.generate(Api,
+        snapshot_path: "test_snapshots_path",
+        migration_path: "test_migration_path",
+        quiet: true,
+        format: false
+      )
+    end
+
+    test "it creates multiple migration files" do
+      assert [custom_index_migration] =
+               Enum.sort(Path.wildcard("test_migration_path/**/*_migrate_resources*.exs"))
+
+      file = File.read!(custom_index_migration)
+
+      assert file =~ ~S<create index(:posts, ["title"], unique: true, nulls_distinct: false)>
+    end
+  end
+
   describe "creating follow up migrations with a schema" do
     setup do
       on_exit(fn ->