Fix :get_dynamic_repo with releases

guides/advanced/scaling.md

@@ -148,14 +148,32 @@ defmodule MyApp.ObanRepo do
 end
 ```
 
+Then add a function to your main Repo
+
+```diff
+defmodule MyApp.Repo do
+  use Ecto.Repo,
+     adapter: Ecto.Adapters.Postgres,
+     otp_app: :my_app
+
++ def oban_repo do
++   if in_transaction?() do
++     MyApp.Repo
++   else
++     MyApp.ObanRepo
++   end
++ end
+end
+```
+
 Then switch the configured `repo`, and use `get_dynamic_repo` to ensure the same repo is used
 within a transaction:
 
 ```diff
  config :my_app, Oban,
 -  repo: MyApp.Repo,
 +  repo: MyApp.ObanRepo,
-+  get_dynamic_repo: fn -> if MyApp.Repo.in_transaction?(), do: MyApp.Repo, else: MyApp.ObanRepo end
++  get_dynamic_repo: {MyApp.Repo, :oban_repo, []}
    ...
 ```
 

lib/oban.ex

@@ -50,7 +50,7 @@ defmodule Oban do
   @type option ::
           {:dispatch_cooldown, pos_integer()}
           | {:engine, module()}
-          | {:get_dynamic_repo, nil | (-> pid() | atom())}
+          | {:get_dynamic_repo, nil | (-> pid() | atom()) | {module(), atom(), list()}}
           | {:log, false | Logger.level()}
           | {:name, name()}
           | {:node, oban_node()}

lib/oban/config.ex

@@ -13,7 +13,7 @@ defmodule Oban.Config do
   @type t :: %__MODULE__{
           dispatch_cooldown: pos_integer(),
           engine: module(),
-          get_dynamic_repo: nil | (-> pid() | atom()),
+          get_dynamic_repo: nil | (-> pid() | atom()) | {module(), atom(), list()},
           insert_trigger: boolean(),
           log: false | Logger.level(),
           name: Oban.name(),
@@ -140,7 +140,7 @@ defmodule Oban.Config do
     Validation.validate_schema(opts,
       dispatch_cooldown: :pos_integer,
       engine: {:behaviour, Oban.Engine},
-      get_dynamic_repo: {:or, [:falsy, {:function, 0}]},
+      get_dynamic_repo: {:or, [:falsy, {:function, 0}, :mfa]},
       insert_trigger: :boolean,
       log: {:enum, @log_levels},
       name: :any,

lib/oban/repo.ex

@@ -191,12 +191,19 @@ defmodule Oban.Repo do
     with_dynamic_repo(conf, name, args ++ [opts])
   end
 
-  defp with_dynamic_repo(%{get_dynamic_repo: fun} = conf, name, args) when is_function(fun, 0) do
+  defp with_dynamic_repo(%{get_dynamic_repo: fun} = conf, name, args)
+       when is_function(fun, 0) or is_tuple(fun) do
     prev_instance = conf.repo.get_dynamic_repo()
 
+    dynamic_repo =
+      case fun do
+        {module, func, args} -> apply(module, func, args)
+        fun -> fun.()
+      end
+
     try do
       if not in_transaction?(conf, prev_instance) do
-        conf.repo.put_dynamic_repo(fun.())
+        conf.repo.put_dynamic_repo(dynamic_repo)
       end
 
       apply(conf.repo, name, args)

lib/oban/validation.ex

@@ -167,6 +167,15 @@ defmodule Oban.Validation do
     end
   end
 
+  defp validate_type(:mfa, key, {module, func, args})
+       when is_atom(module) and is_atom(func) and is_list(args) do
+    if function_exported?(module, func, length(args)) do
+      :ok
+    else
+      {:error, "missing function #{Exception.format_mfa(module, func, length(args))} for #{key}"}
+    end
+  end
+
   defp validate_type(:schedule, key, val) do
     case Expression.parse(val) do
       {:ok, _cron} ->

test/oban/repo_test.exs

@@ -5,7 +5,23 @@ defmodule Oban.RepoTest do
 
   @moduletag :unboxed
 
-  test "querying with a dynamic repo" do
+  test "querying with a dynamic repo (MFA)" do
+    {:ok, repo_pid} = start_supervised({DynamicRepo, name: nil})
+
+    DynamicRepo.put_dynamic_repo(nil)
+
+    name =
+      start_supervised_oban!(
+        get_dynamic_repo: {DynamicRepo, :use_dynamic_repo, [repo_pid]},
+        repo: DynamicRepo
+      )
+
+    conf = Oban.config(name)
+
+    Oban.Repo.insert!(conf, Worker.new(%{ref: 1, action: "OK"}))
+  end
+
+  test "querying with a dynamic repo (anonymous function)" do
     {:ok, repo_pid} = start_supervised({DynamicRepo, name: nil})
 
     DynamicRepo.put_dynamic_repo(nil)

test/support/repo.ex

@@ -13,6 +13,10 @@ defmodule Oban.Test.DynamicRepo do
     otp_app: :oban,
     adapter: Ecto.Adapters.Postgres
 
+  def use_dynamic_repo(pid) do
+    pid
+  end
+
   def init(_, _) do
     {:ok, Oban.Test.Repo.config()}
   end