Includes timestamps macro to the Collection module to handle inserted_at and updated_at attributes (#145)

Author: carlosliracl

lib/mongo/collection.ex

@@ -278,7 +278,7 @@ defmodule Mongo.Collection do
 
         defmodule Board do
 
-        use Collection
+          use Collection
 
           collection "boards" do
 
@@ -358,6 +358,94 @@ defmodule Mongo.Collection do
           "modified" : ISODate("2020-05-19T15:15:14.374Z"),
           "title" : "Vega"
         }
+  ## Example `timestamps`
+
+        defmodule Post do
+
+          use Mongo.Collection
+
+          collection "posts" do
+            attribute :title, String.t()
+            timestamps()
+          end
+
+          def new(title) do
+            Map.put(new(), :title, title)
+          end
+
+          def store(post) do
+            MyRepo.insert_or_update(post)
+          end
+        end
+
+  In this example the macro `timestamps` is used to create two DateTime attributes, `inserted_at` and `updated_at`.
+  This macro is intented to use with the Repo module, as it will be responsible for updating the value of `updated_at` attribute before execute the action.
+
+        iex(1)> post = Post.new("lorem ipsum dolor sit amet")
+        %Post{
+          _id: #BSON.ObjectId<6327a7099626f7f61607e179>,
+          inserted_at: ~U[2022-09-18 23:17:29.087092Z],
+          title: "lorem ipsum dolor sit amet",
+          updated_at: ~U[2022-09-18 23:17:29.087070Z]
+        }
+
+        iex(2)> Post.store(post)
+        {:ok,
+         %{
+           _id: #BSON.ObjectId<6327a7099626f7f61607e179>,
+           inserted_at: ~U[2022-09-18 23:17:29.087092Z],
+           title: "lorem ipsum dolor sit amet",
+           updated_at: ~U[2022-09-18 23:19:24.516648Z]
+         }}
+
+  Is possible to change the field names, like Ecto does, and also change the default behaviour:
+
+        defmodule Comment do
+
+          use Mongo.Collection
+
+          collection "comments" do
+            attribute :text, String.t()
+            timestamps(inserted_at: :created, updated_at: :modified, default: &__MODULE__.truncated_date_time/0)
+          end
+
+          def new(text) do
+            Map.put(new(), :text, text)
+          end
+
+          def truncated_date_time() do
+            utc_now = DateTime.utc_now()
+            DateTime.truncate(utc_now, :second)
+          end
+        end
+
+        iex(1)> comment = Comment.new("useful comment")
+        %Comment{
+          _id: #BSON.ObjectId<6327aa979626f7f616ae5b4a>,
+          created: ~U[2022-09-18 23:32:39Z],
+          modified: ~U[2022-09-18 23:32:39Z],
+          text: "useful comment"
+        }
+
+        iex(2)> {:ok, comment} = MyRepo.insert(comment)
+        {:ok,
+         %Comment{
+           _id: #BSON.ObjectId<6327aa979626f7f616ae5b4a>,
+           created: ~U[2022-09-18 23:32:39Z],
+           modified: ~U[2022-09-18 23:32:42Z],
+           text: "useful comment"
+         }}
+
+        iex(3)> {:ok, comment} = MyRepo.update(%{comment | text: "not so useful comment"})
+        {:ok,
+         %Comment{
+           _id: #BSON.ObjectId<6327aa979626f7f616ae5b4a>,
+           created: ~U[2022-09-18 23:32:39Z],
+           modified: ~U[2022-09-18 23:32:46Z],
+           text: not so useful comment"
+         }}
+
+  The `timestamps` macro has some limitations as it does not run in batch commands like `insert_all` or `update_all`, nor does it update embedded documents.
 
   """
 
@@ -376,6 +464,7 @@ defmodule Mongo.Collection do
 
       Module.register_attribute(__MODULE__, :attributes, accumulate: true)
       Module.register_attribute(__MODULE__, :derived, accumulate: true)
+      Module.register_attribute(__MODULE__, :timestamps, accumulate: true)
       Module.register_attribute(__MODULE__, :types, accumulate: true)
       Module.register_attribute(__MODULE__, :embed_ones, accumulate: true)
       Module.register_attribute(__MODULE__, :embed_manys, accumulate: true)
@@ -440,6 +529,7 @@ defmodule Mongo.Collection do
         Collection.__type__(@types)
 
         def __collection__(:attributes), do: unquote(attribute_names)
+        def __collection__(:timestamps), do: unquote(@timestamps)
         def __collection__(:types), do: @types
         def __collection__(:collection), do: unquote(@collection)
         def __collection__(:id), do: unquote(elem(@id_generator, 0))
@@ -565,12 +655,29 @@ defmodule Mongo.Collection do
         end
       end
 
+    timestamps_function =
+      quote unquote: false do
+        def timestamps(nil) do
+          nil
+        end
+
+        def timestamps(xs) when is_list(xs) do
+          Enum.map(xs, fn struct -> timestamps(struct) end)
+        end
+
+        def timestamps(struct) do
+          updated_at = @timestamps[:updated_at]
+          Collection.timestamps(struct, updated_at, @attributes[updated_at])
+        end
+      end
+
     quote do
       unquote(prelude)
       unquote(postlude)
       unquote(new_function)
       unquote(load_function)
       unquote(dump_function)
+      unquote(timestamps_function)
     end
   end
 
@@ -708,6 +815,34 @@ defmodule Mongo.Collection do
     Module.put_attribute(mod, :attributes, {name, opts})
   end
 
+  @doc """
+  Defines the `timestamps/1` function.
+  """
+  defmacro timestamps(opts \\ []) do
+    quote bind_quoted: [opts: opts] do
+      inserted_at = Keyword.get(opts, :inserted_at, :inserted_at)
+      updated_at = Keyword.get(opts, :updated_at, :updated_at)
+      type = Keyword.get(opts, :type, DateTime)
+
+      new_opts =
+        opts
+        |> Keyword.drop([:inserted_at, :updated_at, :type])
+        |> Keyword.put_new(:default, &DateTime.utc_now/0)
+
+      Module.put_attribute(__MODULE__, :timestamps, {:inserted_at, inserted_at})
+      Module.put_attribute(__MODULE__, :timestamps, {:updated_at, updated_at})
+
+      Collection.__attribute__(__MODULE__, inserted_at, Macro.escape(type), new_opts)
+      Collection.__attribute__(__MODULE__, updated_at, Macro.escape(type), new_opts)
+    end
+  end
+
+  def timestamps(struct, nil, _default), do: struct
+
+  def timestamps(struct, updated_at, opts) do
+    Map.put(struct, updated_at, opts[:default].())
+  end
+
   def dump(%{__struct__: _} = struct) do
     map = Map.from_struct(struct)
     :maps.map(&dump/2, map) |> filter_nils()

lib/mongo/repo.ex

@@ -63,6 +63,7 @@ defmodule Mongo.Repo do
       unless @read_only do
         def insert(%{__struct__: module} = doc, opts \\ []) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
 
           case Mongo.insert_one(@topology, collection, module.dump(doc), opts) do
             {:error, reason} -> {:error, reason}
@@ -72,6 +73,7 @@ defmodule Mongo.Repo do
 
         def update(%{__struct__: module, _id: id} = doc) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
 
           case Mongo.update_one(@topology, collection, %{_id: id}, %{"$set" => module.dump(doc)}, []) do
             {:error, reason} -> {:error, reason}
@@ -81,6 +83,7 @@ defmodule Mongo.Repo do
 
         def insert_or_update(%{__struct__: module, _id: id} = doc) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
 
           case Mongo.update_one(@topology, collection, %{_id: id}, %{"$set" => module.dump(doc)}, upsert: true) do
             {:error, reason} -> {:error, reason}
@@ -101,18 +104,21 @@ defmodule Mongo.Repo do
 
         def insert!(%{__struct__: module} = doc, opts \\ []) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
           %{inserted_id: id} = Mongo.insert_one!(@topology, collection, module.dump(doc), opts)
           %{doc | _id: id}
         end
 
         def update!(%{__struct__: module, _id: id} = doc) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
           Mongo.update_one!(@topology, collection, %{_id: id}, %{"$set" => module.dump(doc)}, [])
           doc
         end
 
         def insert_or_update!(%{__struct__: module, _id: id} = doc) do
           collection = module.__collection__(:collection)
+          doc = module.timestamps(doc)
           update_one_result = Mongo.update_one!(@topology, collection, %{_id: id}, %{"$set" => module.dump(doc)}, upsert: true)
 
           case update_one_result do

test/collections/simple_test.exs

@@ -37,9 +37,8 @@ defmodule Collections.SimpleTest do
 
     collection "cards" do
       attribute :title, String.t(), default: "new title"
-      attribute :created, DateString.t(), default: &DateTime.utc_now/0
-      attribute :modified, DateString.t(), default: &DateTime.utc_now/0
       embeds_one(:label, Label, default: &Label.new/0)
+      timestamps(inserted_at: :created, updated_at: :modified)
     end
 
     def insert_one(%Card{} = card, top) do

test/mongo/repo_test.exs

@@ -12,6 +12,7 @@ defmodule Mongo.RepoTest do
 
     collection "posts" do
       attribute :title, String.t()
+      timestamps()
     end
   end
 
@@ -343,10 +344,12 @@ defmodule Mongo.RepoTest do
         |> Map.put(:title, "test")
         |> MyRepo.insert()
 
-      {:ok, %Post{title: "updated"}} =
+      {:ok, %Post{title: "updated"} = updated} =
         post
         |> Map.put(:title, "updated")
         |> MyRepo.update()
+
+      assert DateTime.compare(post.updated_at, updated.updated_at) == :lt
     end
 
     test "updates a document without changes" do
@@ -366,10 +369,13 @@ defmodule Mongo.RepoTest do
         |> Map.put(:title, "test")
         |> MyRepo.insert()
 
-      %Post{title: "updated"} =
+      updated =
         post
         |> Map.put(:title, "updated")
         |> MyRepo.update!()
+
+      assert updated.title == "updated"
+      assert DateTime.compare(post.updated_at, updated.updated_at) == :lt
     end
 
     test "updates a document without changes" do
@@ -405,6 +411,7 @@ defmodule Mongo.RepoTest do
 
       assert Map.get(post, :_id) == Map.get(updated, :_id)
       assert updated.title == "updated"
+      assert DateTime.compare(post.updated_at, updated.updated_at) == :lt
     end
 
     test "updates a document without changes if it does already exist" do
@@ -443,6 +450,7 @@ defmodule Mongo.RepoTest do
 
       assert Map.get(post, :_id) == Map.get(updated, :_id)
       assert updated.title == "updated"
+      assert DateTime.compare(post.updated_at, updated.updated_at) == :lt
     end
 
     test "updates a document without changes if it does already exist" do