Return 422 instead of 500 when workflow create body omits edges, jobs, or triggers

CHANGELOG.md

@@ -58,6 +58,10 @@ and this project adheres to
 
 ### Fixed
 
+- The workflows REST API now returns a 422 validation error instead of a 500
+  when a create request omits `edges`, `jobs`, or `triggers` from the body
+  rather than sending them as empty lists.
+  [#4982](https://github.com/OpenFn/lightning/issues/4982)
 - Sandbox merge no longer deletes a workflow that was added to the project after
   the sandbox was branched. Such workflows were never part of the sandbox, so
   they are excluded from the merge screen entirely. Workflows deleted inside the

lib/lightning_web/controllers/api/workflows_controller.ex

@@ -413,6 +413,14 @@ defmodule LightningWeb.API.WorkflowsController do
        ),
        do: validate_workflow(edges, jobs, triggers, ids_map)
 
+  defp validate_workflow(%{} = params, ids_map) do
+    edges = Map.get(params, "edges", [])
+    jobs = Map.get(params, "jobs", [])
+    triggers = Map.get(params, "triggers", [])
+
+    validate_workflow(edges, jobs, triggers, ids_map)
+  end
+
   defp validate_workflow(edges, jobs, triggers, ids_map) do
     # {:ok, _ids} <- validate_ids(edges),
     with {:ok, triggers_ids} <- validate_ids(triggers),

test/lightning_web/controllers/api/workflows_controller_test.exs

@@ -745,6 +745,25 @@ defmodule LightningWeb.API.WorkflowsControllerTest do
              }
     end
 
+    test "returns 422 when edges, jobs and triggers are omitted", %{
+      conn: conn,
+      project: project
+    } do
+      conn =
+        post(
+          conn,
+          ~p"/api/projects/#{project.id}/workflows",
+          Jason.encode!(%{name: "workflow without children"})
+        )
+
+      assert json_response(conn, 422) == %{
+               "id" => nil,
+               "errors" => %{
+                 "edges" => ["Missing edge with source_trigger_id."]
+               }
+             }
+    end
+
     test "returns 422 when edges has multiple source triggers", %{
       conn: conn,
       project: project