Allow --repo option & --migration-dir for phx.gen.schema (#4905)

* Allow --repo option for phx.gen.schema

* Add tests for the repo and migration-dir options in schema generator

The `repo` and `migration-dir` options change the location of the
migrations directory, either to the specified directory or one that
matches the repo name (underscored).

The default is explicitly set to "repo" if neither option is set, to
ensure backwards compatability even if the repo has a different name
than the typical `MyApp.Repo`.

---------

Co-authored-by: Gary Rennie <gazler@gmail.com>

lib/mix/tasks/phx.gen.schema.ex

@@ -86,6 +86,21 @@ defmodule Mix.Tasks.Phx.Gen.Schema do
   Generated migration can use `binary_id` for schema's primary key
   and its references with option `--binary-id`.
 
+  ## repo
+
+  Generated migration can use `repo` to set the migration repository
+  folder with option `--repo`:
+
+      $ mix phx.gen.schema Blog.Post posts --repo MyApp.Repo.Auth
+
+  ## migration_dir
+
+  Generated migrations can be added to a specific `--migration-dir` which sets
+  the migration folder path:
+
+      $ mix phx.gen.schema Blog.Post posts --migration-dir /path/to/directory
+
+
   ## prefix
 
   By default migrations and schemas are generated without a prefix.
@@ -130,8 +145,8 @@ defmodule Mix.Tasks.Phx.Gen.Schema do
 
   alias Mix.Phoenix.Schema
 
-  @switches [migration: :boolean, binary_id: :boolean, table: :string,
-             web: :string, context_app: :string, prefix: :string]
+  @switches [migration: :boolean, binary_id: :boolean, table: :string, web: :string,
+    context_app: :string, prefix: :string, repo: :string, migration_dir: :string]
 
   @doc false
   def run(args) do
@@ -164,10 +179,17 @@ defmodule Mix.Tasks.Phx.Gen.Schema do
       parent_opts
       |> Keyword.merge(schema_opts)
       |> put_context_app(schema_opts[:context_app])
+      |> maybe_update_repo_module()
 
-    schema = Schema.new(schema_name, plural, attrs, opts)
+    Schema.new(schema_name, plural, attrs, opts)
+  end
 
-    schema
+  defp maybe_update_repo_module(opts) do
+    if is_nil(opts[:repo]) do
+      opts
+    else
+      Keyword.update!(opts, :repo, &Module.concat([&1]))
+    end
   end
 
   defp put_context_app(opts, nil), do: opts
@@ -181,12 +203,26 @@ defmodule Mix.Tasks.Phx.Gen.Schema do
   end
 
   @doc false
-  def copy_new_files(%Schema{context_app: ctx_app} = schema, paths, binding) do
+  def copy_new_files(%Schema{context_app: ctx_app, repo: repo, opts: opts} = schema, paths, binding) do
     files = files_to_be_generated(schema)
     Mix.Phoenix.copy_from(paths, "priv/templates/phx.gen.schema", binding, files)
 
     if schema.migration? do
-      migration_path = Mix.Phoenix.context_app_path(ctx_app, "priv/repo/migrations/#{timestamp()}_create_#{schema.table}.exs")
+      migration_dir =
+        cond do
+          migration_dir = opts[:migration_dir] ->
+            migration_dir
+
+          opts[:repo] ->
+            repo_name = repo |> Module.split() |> List.last() |> Macro.underscore()
+            Mix.Phoenix.context_app_path(ctx_app, "priv/#{repo_name}/migrations/")
+
+          true ->
+            Mix.Phoenix.context_app_path(ctx_app, "priv/repo/migrations/")
+        end
+
+      migration_path = Path.join(migration_dir, "#{timestamp()}_create_#{schema.table}.exs")
+
       Mix.Phoenix.copy_from paths, "priv/templates/phx.gen.schema", binding, [
         {:eex, "migration.exs", migration_path},
       ]

test/mix/tasks/phx.gen.schema_test.exs

@@ -113,6 +113,40 @@ defmodule Mix.Tasks.Phx.Gen.SchemaTest do
     end
   end
 
+  test "allows a custom repo", config do
+    in_tmp_project config.test, fn ->
+      Gen.Schema.run(~w(Blog.Post blog_posts title:string --repo MyApp.CustomRepo))
+
+      assert [migration] = Path.wildcard("priv/custom_repo/migrations/*_create_blog_posts.exs")
+      assert_file migration, fn file ->
+        assert file =~ "defmodule MyApp.CustomRepo.Migrations.CreateBlogPosts do"
+      end
+    end
+  end
+
+  test "allows a custom migration dir", config do
+    in_tmp_project config.test, fn ->
+      Gen.Schema.run(~w(Blog.Post blog_posts title:string --migration-dir priv/custom_dir))
+
+      assert [migration] = Path.wildcard("priv/custom_dir/*_create_blog_posts.exs")
+      assert_file migration, fn file ->
+        assert file =~ "defmodule Phoenix.Repo.Migrations.CreateBlogPosts do"
+      end
+    end
+  end
+
+  test "custom migration_dir takes precedence over custom repo name", config do
+    in_tmp_project config.test, fn ->
+      Gen.Schema.run(~w(Blog.Post blog_posts title:string \
+        --repo MyApp.CustomRepo --migration-dir priv/custom_dir))
+
+      assert [migration] = Path.wildcard("priv/custom_dir/*_create_blog_posts.exs")
+      assert_file migration, fn file ->
+        assert file =~ "defmodule MyApp.CustomRepo.Migrations.CreateBlogPosts do"
+      end
+    end
+  end
+
   test "does not add maps to the required list", config do
     in_tmp_project config.test, fn ->
       Gen.Schema.run(~w(Blog.Post blog_posts title:string tags:map published_at:naive_datetime))