improvement: Forbid reserved field names (#388)

Co-authored-by: Juha Lehtonen <juha.lehtonen@relexsolutions.com>

lib/ash/resource.ex

@@ -275,4 +275,16 @@ defmodule Ash.Resource do
         end
     end
   end
+
+  @doc false
+  def reserved_names do
+    [
+      :__struct__,
+      :__meta__,
+      :__metadata__,
+      :__order__,
+      :calculations,
+      :aggregates
+    ]
+  end
 end

lib/ash/resource/dsl.ex

@@ -1210,6 +1210,7 @@ defmodule Ash.Resource.Dsl do
     Ash.Resource.Transformers.DefaultAccept,
     Ash.Resource.Transformers.SetTypes,
     Ash.Resource.Transformers.RequireUniqueFieldNames,
+    Ash.Resource.Transformers.NoReservedFieldNames,
     Ash.Resource.Transformers.ValidateRelationshipAttributes,
     Ash.Resource.Transformers.ValidateEagerIdentities,
     Ash.Resource.Transformers.ValidateAggregatesSupported,

lib/ash/resource/schema.ex

@@ -14,7 +14,8 @@ defmodule Ash.Schema do
         @primary_key false
 
         embedded_schema do
-          for attribute <- Ash.Resource.Info.attributes(__MODULE__) do
+          for attribute <- Ash.Resource.Info.attributes(__MODULE__),
+              attribute.name not in Ash.Resource.reserved_names() do
             read_after_writes? = attribute.generated? and is_nil(attribute.default)
 
             constraint_opts =
@@ -57,7 +58,8 @@ defmodule Ash.Schema do
             Module.put_attribute(__MODULE__, :ash_struct_fields, field)
           end
 
-          for relationship <- Ash.Resource.Info.relationships(__MODULE__) do
+          for relationship <- Ash.Resource.Info.relationships(__MODULE__),
+              relationship.name not in Ash.Resource.reserved_names() do
             Module.put_attribute(
               __MODULE__,
               :ash_struct_fields,
@@ -65,7 +67,8 @@ defmodule Ash.Schema do
             )
           end
 
-          for aggregate <- Ash.Resource.Info.aggregates(__MODULE__) do
+          for aggregate <- Ash.Resource.Info.aggregates(__MODULE__),
+              aggregate.name not in Ash.Resource.reserved_names() do
             {:ok, type} = Aggregate.kind_to_type(aggregate.kind, :string)
 
             field(aggregate.name, Ash.Type.ecto_type(type), virtual: true)
@@ -77,7 +80,8 @@ defmodule Ash.Schema do
             )
           end
 
-          for calculation <- Ash.Resource.Info.calculations(__MODULE__) do
+          for calculation <- Ash.Resource.Info.calculations(__MODULE__),
+              calculation.name not in Ash.Resource.reserved_names() do
             {mod, _} = calculation.calculation
 
             field(calculation.name, Ash.Type.ecto_type(calculation.type), virtual: true)
@@ -102,7 +106,8 @@ defmodule Ash.Schema do
         @primary_key false
 
         schema Ash.DataLayer.source(__MODULE__) do
-          for attribute <- Ash.Resource.Info.attributes(__MODULE__) do
+          for attribute <- Ash.Resource.Info.attributes(__MODULE__),
+              attribute.name not in Ash.Resource.reserved_names() do
             read_after_writes? = attribute.generated? and is_nil(attribute.default)
 
             constraint_opts =
@@ -145,7 +150,8 @@ defmodule Ash.Schema do
             Module.put_attribute(__MODULE__, :ash_struct_fields, field)
           end
 
-          for relationship <- Ash.Resource.Info.relationships(__MODULE__) do
+          for relationship <- Ash.Resource.Info.relationships(__MODULE__),
+              relationship.name not in Ash.Resource.reserved_names() do
             Module.put_attribute(
               __MODULE__,
               :ash_struct_fields,
@@ -153,7 +159,8 @@ defmodule Ash.Schema do
             )
           end
 
-          for aggregate <- Ash.Resource.Info.aggregates(__MODULE__) do
+          for aggregate <- Ash.Resource.Info.aggregates(__MODULE__),
+              aggregate.name not in Ash.Resource.reserved_names() do
             {:ok, type} = Aggregate.kind_to_type(aggregate.kind, :string)
 
             field(aggregate.name, Ash.Type.ecto_type(type), virtual: true)
@@ -165,7 +172,8 @@ defmodule Ash.Schema do
             )
           end
 
-          for calculation <- Ash.Resource.Info.calculations(__MODULE__) do
+          for calculation <- Ash.Resource.Info.calculations(__MODULE__),
+              calculation.name not in Ash.Resource.reserved_names() do
             {mod, _} = calculation.calculation
 
             field(calculation.name, Ash.Type.ecto_type(calculation.type), virtual: true)

lib/ash/resource/transformers/no_reserved_field_names.ex

@@ -0,0 +1,60 @@
+defmodule Ash.Resource.Transformers.NoReservedFieldNames do
+  @moduledoc """
+  Confirms that a resource does not use reserved names for field names.
+
+  Reserved field names are: #{inspect(Ash.Resource.reserved_names())}.
+  """
+  use Spark.Dsl.Transformer
+
+  alias Spark.Dsl.Transformer
+  alias Spark.Error.DslError
+
+  def transform(dsl_state) do
+    resource = Transformer.get_persisted(dsl_state, :module)
+
+    attributes =
+      dsl_state
+      |> Transformer.get_entities([:attributes])
+
+    relationships =
+      dsl_state
+      |> Transformer.get_entities([:relationships])
+
+    calculations =
+      dsl_state
+      |> Transformer.get_entities([:calculations])
+
+    aggregates =
+      dsl_state
+      |> Transformer.get_entities([:aggregates])
+
+    attributes
+    |> Enum.concat(relationships)
+    |> Enum.concat(calculations)
+    |> Enum.concat(aggregates)
+    |> Enum.each(fn %{name: name} = field ->
+      if name in Ash.Resource.reserved_names() do
+        path =
+          case field do
+            %Ash.Resource.Aggregate{kind: kind} -> [:aggregates, kind, name]
+            %Ash.Resource.Calculation{} -> [:calculations, name]
+            %Ash.Resource.Attribute{} -> [:attributes, name]
+            %{type: type} -> [:relationships, type, name]
+          end
+
+        raise DslError,
+          message: """
+          Field #{name} is using a reserved name.
+
+          Reserved field names are: #{inspect(Ash.Resource.reserved_names())}
+          """,
+          path: path,
+          module: resource
+      end
+    end)
+
+    {:ok, dsl_state}
+  end
+
+  def after_compile?, do: true
+end

test/resource/attributes_test.exs

@@ -91,5 +91,25 @@ defmodule Ash.Test.Resource.AttributesTest do
         end
       )
     end
+
+    test "raises if you pass a reserved name for `name`" do
+      for name <- Ash.Resource.reserved_names() do
+        assert_raise(
+          Spark.Error.DslError,
+          ~r/Field #{name} is using a reserved name/,
+          fn ->
+            defmodule :"Elixir.Resource#{name}" do
+              @moduledoc false
+              use Ash.Resource
+
+              attributes do
+                uuid_primary_key :id
+                attribute name, :string
+              end
+            end
+          end
+        )
+      end
+    end
   end
 end