improvement: error_fields for custom_index

fix: proper return types for updates from queries
fix: allow atomics to return `nil`

lib/custom_index.ex

@@ -3,6 +3,7 @@ defmodule AshPostgres.CustomIndex do
   @fields [
     :table,
     :fields,
+    :error_fields,
     :name,
     :unique,
     :concurrently,
@@ -23,6 +24,10 @@ defmodule AshPostgres.CustomIndex do
       type: {:wrap_list, {:or, [:atom, :string]}},
       doc: "The fields to include in the index."
     ],
+    error_fields: [
+      type: {:list, :atom},
+      doc: "The fields to attach the error to."
+    ],
     name: [
       type: :string,
       doc: "the name of the index. Defaults to \"\#\{table\}_\#\{column\}_index\"."
@@ -68,6 +73,30 @@ defmodule AshPostgres.CustomIndex do
   def schema, do: @schema
 
   def transform(index) do
+    with {:ok, index} <- set_name(index) do
+      set_error_fields(index)
+    end
+  end
+
+  defp set_error_fields(index) do
+    if index.error_fields do
+      {:ok, index}
+    else
+      {:ok, %{index | error_fields: Enum.flat_map(index.fields, fn field ->
+          if Regex.match?(~r/^[0-9a-zA-Z_]+$/, to_string(field)) do
+            if is_binary(field) do
+              [String.to_atom(field)]
+            else
+              [field]
+            end
+            else
+            []
+          end
+        end)}}
+    end
+  end
+
+  defp set_name(index) do
     cond do
       index.name ->
         if Regex.match?(~r/^[0-9a-zA-Z_]+$/, index.name) do

lib/data_layer.ex

@@ -1271,6 +1271,9 @@ defmodule AshPostgres.DataLayer do
           query
         end
 
+      repo = dynamic_repo(resource, changeset)
+      repo_opts = repo_opts(changeset.timeout, changeset.tenant, changeset.resource)
+
       case query_with_atomics(
              resource,
              query,
@@ -1280,16 +1283,17 @@ defmodule AshPostgres.DataLayer do
              []
            ) do
         :empty ->
-          {:ok, changeset.data}
+          if options[:return_records?] do
+            if changeset.context[:data_layer][:use_atomic_update_data?] do
+              {:ok, [changeset.data]}
+            else
+              {:ok, repo.all(query)}
+            end
+          else
+            :ok
+          end
 
         {:ok, query} ->
-          repo_opts = repo_opts(changeset.timeout, changeset.tenant, changeset.resource)
-
-          repo_opts =
-            Keyword.put(repo_opts, :returning, Keyword.keys(changeset.atomics))
-
-          repo = dynamic_repo(resource, changeset)
-
           {_, results} =
             with_savepoint(repo, query, fn ->
               repo.update_all(
@@ -2105,13 +2109,14 @@ defmodule AshPostgres.DataLayer do
   end
 
   defp add_unique_indexes(changeset, resource, ash_changeset) do
+    table = table(resource, ash_changeset)
     changeset =
       resource
       |> Ash.Resource.Info.identities()
       |> Enum.reduce(changeset, fn identity, changeset ->
         name =
           AshPostgres.DataLayer.Info.identity_index_names(resource)[identity.name] ||
-            "#{table(resource, ash_changeset)}_#{identity.name}_index"
+            "#{table}_#{identity.name}_index"
 
         opts =
           if Map.get(identity, :message) do
@@ -2127,14 +2132,26 @@ defmodule AshPostgres.DataLayer do
       resource
       |> AshPostgres.DataLayer.Info.custom_indexes()
       |> Enum.reduce(changeset, fn index, changeset ->
+        name = index.name || AshPostgres.CustomIndex.name(table, index)
+
         opts =
           if index.message do
-            [name: index.name, message: index.message]
+            [name: name, message: index.message]
           else
-            [name: index.name]
+            [name: name]
+          end
+
+        fields =
+          if index.error_fields do
+            index.error_fields
+          else
+            case Enum.filter(index.fields, &is_atom/1) do
+              [] -> Ash.Resource.Info.primary_key(resource)
+              fields -> fields
+            end
           end
 
-        Ecto.Changeset.unique_constraint(changeset, index.fields, opts)
+        Ecto.Changeset.unique_constraint(changeset, fields, opts)
       end)
 
     names =

lib/expr.ex

@@ -39,15 +39,16 @@ defmodule AshPostgres.Expr do
 
   def dynamic_expr(query, expr, bindings, embedded? \\ false, type \\ nil, acc \\ %ExprInfo{})
 
+  def dynamic_expr(_query, %Filter{expression: nil}, _bindings, _embedded?, _type, acc) do
+    # a nil filter means everything
+    {true, acc}
+  end
+
   def dynamic_expr(query, %Filter{expression: expression}, bindings, embedded?, type, acc) do
     dynamic_expr(query, expression, bindings, embedded?, type, acc)
   end
 
-  # A nil filter means "everything"
-  def dynamic_expr(_, nil, _, _, _, acc), do: {true, acc}
-  # A true filter means "everything"
   def dynamic_expr(_, true, _, _, _, acc), do: {true, acc}
-  # A false filter means "nothing"
   def dynamic_expr(_, false, _, _, _, acc), do: {false, acc}
 
   def dynamic_expr(query, expression, bindings, embedded?, type, acc) do