poc: support virtual embeds

integration_test/cases/repo.exs

@@ -6,6 +6,7 @@ defmodule Ecto.Integration.RepoTest do
 
   alias Ecto.Integration.Post
   alias Ecto.Integration.Order
+  alias Ecto.Integration.Item
   alias Ecto.Integration.User
   alias Ecto.Integration.Comment
   alias Ecto.Integration.Permalink
@@ -1300,10 +1301,17 @@ defmodule Ecto.Integration.RepoTest do
   end
 
   test "virtual field" do
-    assert %Post{id: id} = TestRepo.insert!(%Post{title: "1"})
+    assert %Post{id: id} = TestRepo.insert!(%Post{title: "1", temp: "special"})
     assert TestRepo.get(Post, id).temp == "temp"
   end
 
+  test "virtual embed" do
+    assert %Order{id: id, last_seen_item: %Item{reference: "1"}} =
+      TestRepo.insert!(%Order{last_seen_item: %Item{reference: "1"}})
+
+    assert %{last_seen_item: nil} = TestRepo.get(Order, id)
+  end
+
   ## Query syntax
 
   defmodule Foo do

integration_test/support/schemas.exs

@@ -266,13 +266,15 @@ defmodule Ecto.Integration.Order do
     * Embedding one schema
     * Preloading items inside embeds_many
     * Preloading items inside embeds_one
+    * Virtual embeds
     * Field source with json_extract_path
 
   """
   use Ecto.Integration.Schema
 
   schema "orders" do
     field :metadata, :map, source: :meta
+    embeds_one :last_seen_item, Ecto.Integration.Item, virtual: true
     embeds_one :item, Ecto.Integration.Item
     embeds_many :items, Ecto.Integration.Item
     belongs_to :permalink, Ecto.Integration.Permalink

lib/ecto/embedded.ex

@@ -28,6 +28,7 @@ defmodule Ecto.Embedded do
     :owner,
     :related,
     :on_cast,
+    virtual: false,
     on_replace: :raise,
     unique: true,
     ordered: true
@@ -144,7 +145,11 @@ defmodule Ecto.Embedded do
   @doc false
   def prepare(changeset, embeds, adapter, repo_action) do
     %{changes: changes, types: types, repo: repo} = changeset
-    prepare(Map.take(changes, embeds), types, adapter, repo, repo_action)
+    #non_virtual_embeds = Enum.reject(embeds, & &1.virtual)
+
+    changes
+    |> Map.take(embeds)
+    |> prepare(types, adapter, repo, repo_action)
   end
 
   defp prepare(embeds, _types, _adapter, _repo, _repo_action) when embeds == %{} do
@@ -153,8 +158,14 @@ defmodule Ecto.Embedded do
 
   defp prepare(embeds, types, adapter, repo, repo_action) do
     Enum.reduce embeds, embeds, fn {name, changeset_or_changesets}, acc ->
-      {:embed, embed} = Map.get(types, name)
-      Map.put(acc, name, prepare_each(embed, changeset_or_changesets, adapter, repo, repo_action))
+      case Map.get(types, name) do
+        {:embed, %{virtual: false} = embed} ->
+          prepared = prepare_each(embed, changeset_or_changesets, adapter, repo, repo_action)
+          Map.put(acc, name, prepared)
+
+        {:embed, %{virtual: true}} ->
+          acc
+      end
     end
   end
 

lib/ecto/schema.ex

@@ -2086,7 +2086,7 @@ defmodule Ecto.Schema do
     Module.put_attribute(mod, :ecto_changeset_fields, {name, {:assoc, struct}})
   end
 
-  @valid_embeds_one_options [:on_replace, :source]
+  @valid_embeds_one_options [:on_replace, :source, :virtual]
 
   @doc false
   def __embeds_one__(mod, name, schema, opts) when is_atom(schema) do
@@ -2099,7 +2099,7 @@ defmodule Ecto.Schema do
           "`embeds_one/3` expects `schema` to be a module name, but received #{inspect(schema)}"
   end
 
-  @valid_embeds_many_options [:on_replace, :source]
+  @valid_embeds_many_options [:on_replace, :source, :virtual]
 
   @doc false
   def __embeds_many__(mod, name, schema, opts) when is_atom(schema) do

test/ecto/embedded_test.exs

@@ -19,6 +19,7 @@ defmodule Ecto.EmbeddedTest do
       field :name, :string
       embeds_one :profile, Profile, on_replace: :delete
       embeds_one :post, Post
+      embeds_one :virtual_post, Post, virtual: true
       embeds_many :posts, Post, on_replace: :delete
     end
   end
@@ -36,7 +37,7 @@ defmodule Ecto.EmbeddedTest do
 
   test "__schema__" do
     assert Author.__schema__(:embeds) ==
-      [:profile, :post, :posts]
+      [:profile, :post, :virtual_post, :posts]
 
     assert Author.__schema__(:embed, :profile) ==
       %Embedded{field: :profile, cardinality: :one, owner: Author, on_replace: :delete, related: Profile}

test/ecto/query/planner_test.exs

@@ -499,7 +499,7 @@ defmodule Ecto.Query.PlannerTest do
 
   test "plan: generates a cache key" do
     {_query, _cast_params, _dump_params, key} = plan(from(Post, []))
-    assert key == [:all, {:from, {"posts", Post, 111065921, "my_prefix"}, []}]
+    assert key == [:all, {:from, {"posts", Post, 23210922, "my_prefix"}, []}]
 
     query =
       from(
@@ -525,7 +525,7 @@ defmodule Ecto.Query.PlannerTest do
                    {:limit, {true, 1}},
                    {:where, [{:and, {:is_nil, [], [nil]}}, {:or, {:is_nil, [], [nil]}}]},
                    {:join, [{:inner, {"comments", Comment, 38292156, "world"}, true, ["join hint"]}]},
-                   {:from, {"posts", Post, 111065921, "hello"}, ["hint"]},
+                   {:from, {"posts", Post, 23210922, "hello"}, ["hint"]},
                    {:select, 1}]
   end