Allow schema fields to be read only (#4335)

---------

Co-authored-by: José Valim <[email protected]>

integration_test/cases/repo.exs

@@ -1304,6 +1304,112 @@ defmodule Ecto.Integration.RepoTest do
     assert TestRepo.get(Post, id).temp == "temp"
   end
 
+  describe "read only fields" do
+    test "select with read only field" do
+      {1, _} = TestRepo.insert_all("posts", [%{title: "1", read_only: "readonly"}])
+      query = from p in Post, where: p.read_only == ^"readonly", select: p.read_only
+
+      assert "readonly" == TestRepo.one(query)
+      assert %{read_only: "readonly"} = TestRepo.one(Post)
+    end
+
+    test "update with read only field" do
+      %Post{id: id} = post = TestRepo.insert!(%Post{title: "1"})
+      cs = Ecto.Changeset.change(post, %{title: "2", read_only: "nope"})
+      TestRepo.update!(cs)
+      assert is_nil(TestRepo.get(Post, id).read_only)
+    end
+
+    @tag :returning
+    test "update with read only field and returning" do
+      post = TestRepo.insert!(%Post{title: "1"})
+      cs = Ecto.Changeset.change(post, %{title: "2", read_only: "nope"})
+      updated_post = TestRepo.update!(cs, returning: true)
+      assert is_nil(updated_post.read_only)
+    end
+
+    test "update_all with read only field" do
+      TestRepo.insert!(%Post{title: "1"})
+      update_query = from p in Post, where: p.title == "1", update: [set: [read_only: "nope"]]
+
+      assert_raise Ecto.QueryError,  ~r/cannot update unwritable field `read_only` in query/, fn ->
+        TestRepo.update_all(update_query, [])
+      end
+    end
+
+    test "insert with read only field" do
+      %Post{id: id} = TestRepo.insert!(%Post{title: "1", read_only: "nope"})
+      assert is_nil(TestRepo.get(Post, id).read_only)
+    end
+
+    @tag :returning
+    test "insert with read only field and returning" do
+      post = TestRepo.insert!(%Post{title: "1", read_only: "nope"}, returning: true)
+      assert is_nil(post.read_only)
+    end
+
+    test "insert with read only field and conflict query" do
+      on_conflict = from Post, update: [set: [read_only: "nope"]]
+
+      assert_raise Ecto.QueryError,  ~r/cannot update unwritable field `read_only` in query/, fn ->
+        TestRepo.insert!(%Post{title: "1"}, on_conflict: on_conflict)
+      end
+
+      assert_raise Ecto.QueryError,  ~r/cannot update unwritable field `read_only` in query/, fn ->
+        TestRepo.insert!(%Post{title: "1"}, on_conflict: [set: [read_only: "nope"]])
+      end
+    end
+
+    test "insert with read only field and conflict replace" do
+      msg = "cannot replace unwritable field `:read_only` in :on_conflict option"
+
+      assert_raise ArgumentError,  msg, fn ->
+        TestRepo.insert!(%Post{title: "1"}, on_conflict: {:replace, [:read_only]})
+      end
+    end
+
+    @tag :with_conflict_target
+    @tag :upsert
+    test "insert with read only field and conflict replace_all" do
+      uuid = Ecto.UUID.generate()
+      TestRepo.insert!(%Post{uuid: uuid, title: "1"})
+      %Post{id: id} = TestRepo.insert!(%Post{uuid: uuid, title: "2"}, conflict_target: [:uuid], on_conflict: :replace_all)
+      assert %{title: "2", read_only: nil} = TestRepo.get(Post, id)
+    end
+
+    @tag :returning
+    @tag :with_conflict_target
+    @tag :upsert
+    test "insert with read only field and conflict replace_all and returning" do
+      uuid = Ecto.UUID.generate()
+      TestRepo.insert!(%Post{uuid: uuid, title: "1"})
+
+      post =
+        TestRepo.insert!(%Post{uuid: uuid, title: "2", read_only: "nope"},
+          conflict_target: [:uuid],
+          on_conflict: :replace_all,
+          returning: true
+        )
+
+      assert %{title: "2", read_only: nil} = post
+    end
+
+    test "insert_all with read only field" do
+      msg = ~r/Unwritable fields, such as virtual and read only fields are not supported./
+
+      assert_raise ArgumentError, msg, fn ->
+        TestRepo.insert_all(Post, [%{title: "1", read_only: "nope"}])
+      end
+
+      msg = "cannot select unwritable field `read_only` for insert_all"
+
+      assert_raise ArgumentError, msg, fn ->
+        query = from p in Post, select: %{read_only: p.read_only}
+        TestRepo.insert_all(Post, query)
+      end
+    end
+  end
+
   ## Query syntax
 
   defmodule Foo do

integration_test/support/schemas.exs

@@ -46,6 +46,7 @@ defmodule Ecto.Integration.Post do
     field :links, {:map, :string}
     field :intensities, {:map, :float}
     field :posted, :date
+    field :read_only, :string, read_only: true
     has_many :comments, Ecto.Integration.Comment, on_delete: :delete_all, on_replace: :delete
     has_many :force_comments, Ecto.Integration.Comment, on_replace: :delete_if_exists
     has_many :ordered_comments, Ecto.Integration.Comment, preload_order: [:text]

lib/ecto/query/planner.ex

@@ -1726,7 +1726,7 @@ defmodule Ecto.Query.Planner do
 
       {:error, {:values, _, [types, _]}} ->
         fields = Keyword.keys(types)
-        dumper = types |> Enum.map(fn {field, type} -> {field, {field, type}} end) |> Enum.into(%{})
+        dumper = types |> Enum.map(fn {field, type} -> {field, {field, type, false}} end) |> Enum.into(%{})
         {types, fields} = select_dump(fields, dumper, ix, drop)
         {{:source, :values, nil, types}, fields}
 
@@ -1749,7 +1749,7 @@ defmodule Ecto.Query.Planner do
     |> Enum.reverse
     |> Enum.reduce({[], []}, fn
       field, {types, exprs} when is_atom(field) and not is_map_key(drop, field) ->
-        {source, type} = Map.get(dumper, field, {field, :any})
+        {source, type, _read_only?} = Map.get(dumper, field, {field, :any, false})
         {[{field, type} | types], [select_field(source, ix) | exprs]}
       _field, acc ->
         acc
@@ -2027,15 +2027,23 @@ defmodule Ecto.Query.Planner do
   defp cte_fields([], [], _aliases), do: []
 
   defp assert_update!(%Ecto.Query{updates: updates} = query, operation) do
+    dumper = dumper_for_update(query)
+
     changes =
       Enum.reduce(updates, %{}, fn update, acc ->
         Enum.reduce(update.expr, acc, fn {_op, kw}, acc ->
           Enum.reduce(kw, acc, fn {k, v}, acc ->
             if Map.has_key?(acc, k) do
               error! query, "duplicate field `#{k}` for `#{operation}`"
-            else
-              Map.put(acc, k, v)
             end
+
+            case dumper do
+              %{^k => {_, _, false}} -> :ok
+              %{} -> error! query, "cannot update unwritable field `#{k}`"
+              nil -> :ok
+            end
+
+            Map.put(acc, k, v)
           end)
         end)
       end)
@@ -2070,6 +2078,16 @@ defmodule Ecto.Query.Planner do
     end
   end
 
+  defp dumper_for_update(query) do
+    case get_source!(:updates, query, 0) do
+      {source, schema, _} when is_binary(source) and schema != nil ->
+        schema.__schema__(:dump)
+
+      _ ->
+        nil
+    end
+  end
+
   defp filter_and_reraise(exception, stacktrace) do
     reraise exception, Enum.reject(stacktrace, &match?({__MODULE__, _, _, _}, &1))
   end

lib/ecto/repo/schema.ex

@@ -104,7 +104,7 @@ defmodule Ecto.Repo.Schema do
     {rows, header, row_cast_params, placeholder_cast_params, placeholder_dump_params, fn -> counter end}
   end
 
-  defp extract_header_and_fields(repo, %Ecto.Query{} = query, _schema, _dumper, _autogen_id, _placeholder_map, adapter, opts) do
+  defp extract_header_and_fields(repo, %Ecto.Query{} = query, _schema, dumper, _autogen_id, _placeholder_map, adapter, opts) do
     {query, opts} = repo.prepare_query(:insert_all, query, opts)
     query = attach_prefix(query, opts)
 
@@ -117,10 +117,22 @@ defmodule Ecto.Repo.Schema do
 
     header = case query.select do
       %Ecto.Query.SelectExpr{expr: {:%{}, _ctx, args}} ->
-        Enum.map(args, &elem(&1, 0))
+        Enum.map(args, fn {field, _} ->
+          case dumper do
+            %{^field => {_, _, false}} -> field
+            %{} -> raise ArgumentError, "cannot select unwritable field `#{field}` for insert_all"
+            nil -> field
+          end
+        end)
 
       %Ecto.Query.SelectExpr{take: %{^ix => {_fun, fields}}} ->
-        fields
+        Enum.map(fields, fn field ->
+          case dumper do
+            %{^field => {_, _, false}} -> field
+            %{} -> raise ArgumentError, "cannot select unwritable field `#{field}` for insert_all"
+            nil -> field
+          end
+        end)
 
       _ ->
         raise ArgumentError, """
@@ -160,15 +172,16 @@ defmodule Ecto.Repo.Schema do
   defp init_mapper(schema, dumper, adapter, placeholder_map) do
     fn {field, value}, acc ->
       case dumper do
-        %{^field => {source, type}} ->
+        %{^field => {source, type, false}} ->
           extract_value(source, value, type, placeholder_map, acc, fn val ->
             dump_field!(:insert_all, schema, field, type, val, adapter)
           end)
 
         %{} ->
           raise ArgumentError,
                 "unknown field `#{inspect(field)}` in schema #{inspect(schema)} given to " <>
-                  "insert_all. Note virtual fields and associations are not supported"
+                  "insert_all. Unwritable fields, such as virtual and read only fields " <>
+                  "are not supported. Associations are also not supported"
       end
     end
   end
@@ -324,7 +337,7 @@ defmodule Ecto.Repo.Schema do
     struct = struct_from_changeset!(:insert, changeset)
     schema = struct.__struct__
     dumper = schema.__schema__(:dump)
-    fields = schema.__schema__(:fields)
+    writable_fields = schema.__schema__(:writable_fields)
     assocs = schema.__schema__(:associations)
     embeds = schema.__schema__(:embeds)
 
@@ -341,7 +354,7 @@ defmodule Ecto.Repo.Schema do
     # On insert, we always merge the whole struct into the
     # changeset as changes, except the primary key if it is nil.
     changeset = put_repo_and_action(changeset, :insert, repo, tuplet)
-    changeset = Relation.surface_changes(changeset, struct, fields ++ assocs)
+    changeset = Relation.surface_changes(changeset, struct, writable_fields ++ assocs)
 
     wrap_in_transaction(adapter, adapter_meta, opts, changeset, assocs, embeds, prepare, fn ->
       assoc_opts = assoc_opts(assocs, opts)
@@ -360,7 +373,7 @@ defmodule Ecto.Repo.Schema do
         {changes, cast_extra, dump_extra, return_types, return_sources} =
           autogenerate_id(autogen_id, changes, return_types, return_sources, adapter)
 
-        changes = Map.take(changes, fields)
+        changes = Map.take(changes, writable_fields)
         autogen = autogenerate_changes(schema, :insert, changes)
 
         dump_changes =
@@ -416,7 +429,7 @@ defmodule Ecto.Repo.Schema do
     struct = struct_from_changeset!(:update, changeset)
     schema = struct.__struct__
     dumper = schema.__schema__(:dump)
-    fields = schema.__schema__(:fields)
+    writable_fields = schema.__schema__(:writable_fields)
     assocs = schema.__schema__(:associations)
     embeds = schema.__schema__(:embeds)
 
@@ -445,7 +458,7 @@ defmodule Ecto.Repo.Schema do
         if changeset.valid? do
           embeds = Ecto.Embedded.prepare(changeset, embeds, adapter, :update)
 
-          changes = changeset.changes |> Map.merge(embeds) |> Map.take(fields)
+          changes = changeset.changes |> Map.merge(embeds) |> Map.take(writable_fields)
           autogen = autogenerate_changes(schema, :update, changes)
           dump_changes = dump_changes!(:update, changes, autogen, schema, [], dumper, adapter)
 
@@ -627,7 +640,7 @@ defmodule Ecto.Repo.Schema do
   end
   defp fields_to_sources(fields, dumper) do
     Enum.reduce(fields, {[], []}, fn field, {types, sources} ->
-      {source, type} = Map.fetch!(dumper, field)
+      {source, type, _read_only?} = Map.fetch!(dumper, field)
       {[{field, type} | types], [source | sources]}
     end)
   end
@@ -687,7 +700,7 @@ defmodule Ecto.Repo.Schema do
   defp conflict_target(conflict_target, dumper) do
     for target <- List.wrap(conflict_target) do
       case dumper do
-        %{^target => {alias, _}} ->
+        %{^target => {alias, _, _}} ->
           alias
         %{} when is_atom(target) ->
           raise ArgumentError, "unknown field `#{inspect(target)}` in conflict_target"
@@ -711,8 +724,7 @@ defmodule Ecto.Repo.Schema do
         {{:nothing, [], conflict_target}, []}
 
       {:replace, keys} when is_list(keys) ->
-        fields = Enum.map(keys, &field_source!(schema, &1))
-        {{fields, [], conflict_target}, []}
+        {{replace_fields!(schema, keys), [], conflict_target}, []}
 
       :replace_all ->
         {{replace_all_fields!(:replace_all, schema, []), [], conflict_target}, []}
@@ -733,12 +745,29 @@ defmodule Ecto.Repo.Schema do
     end
   end
 
+  defp replace_fields!(nil, fields), do: fields
+
+  defp replace_fields!(schema, fields) do
+    dumper = schema.__schema__(:dump)
+
+    Enum.map(fields, fn field ->
+      case dumper do
+        %{^field => {source, _type, false}} ->
+          source
+
+        _ ->
+          raise ArgumentError,
+                "cannot replace unwritable field `#{inspect(field)}` in :on_conflict option"
+      end
+    end)
+  end
+
   defp replace_all_fields!(kind, nil, _to_remove) do
     raise ArgumentError, "cannot use #{inspect(kind)} on operations without a schema"
   end
 
   defp replace_all_fields!(_kind, schema, to_remove) do
-    Enum.map(schema.__schema__(:fields) -- to_remove, &field_source!(schema, &1))
+    Enum.map(schema.__schema__(:writable_fields) -- to_remove, &field_source!(schema, &1))
   end
 
   defp field_source!(nil, field) do
@@ -1054,7 +1083,7 @@ defmodule Ecto.Repo.Schema do
 
   defp dump_fields!(action, schema, kw, dumper, adapter) do
     for {field, value} <- kw do
-      {alias, type} = Map.fetch!(dumper, field)
+      {alias, type, _read_only?} = Map.fetch!(dumper, field)
       {alias, dump_field!(action, schema, field, type, value, adapter)}
     end
   end