.

djangorota/rota/services.py

@@ -1,6 +1,7 @@
 import threading
 import traceback
-from typing import Optional
+import io
+import contextlib
 
 from django.utils import timezone
 
@@ -34,7 +35,27 @@ def _run_rota_job(run_id: int, use_external_generator: bool = False, generate_bu
             try:
                 from project_rota_hook import generate_rota_for_schedule  # type: ignore
 
-                result = generate_rota_for_schedule(rota)
+                # Capture any stdout/stderr produced by the external generator
+                out_buf = io.StringIO()
+                err_buf = io.StringIO()
+                with contextlib.redirect_stdout(out_buf), contextlib.redirect_stderr(err_buf):
+                    result = generate_rota_for_schedule(rota)
+                # Attach captured output to the result for debugging
+                try:
+                    result = result or {}
+                    result["generator_stdout"] = out_buf.getvalue()
+                    result["generator_stderr"] = err_buf.getvalue()
+                except Exception:
+                    pass
+                # Also persist captured generator output into the run.log so
+                # it's visible from the run detail page when executed in the
+                # background thread.
+                try:
+                    captured = "\n[GENERATOR STDOUT]\n" + (result.get("generator_stdout") or "") + "\n[GENERATOR STDERR]\n" + (result.get("generator_stderr") or "")
+                    run.log = (run.log or "") + captured
+                    run.save(update_fields=["log"])
+                except Exception:
+                    pass
             except Exception:
                 tb = traceback.format_exc()
                 run.mark_failed(message=tb)
@@ -51,25 +72,54 @@ def _run_rota_job(run_id: int, use_external_generator: bool = False, generate_bu
         # result. This allows the web UI to present the generated HTML for a
         # run without requiring a separate on-demand build.
         if generate_builder:
+            # Defensive: if no workers are assigned to the rota, skip the
+            # builder step and return a clear message rather than raising an
+            # exception from deep inside the builder.
             try:
-                rb = rota.to_rota_builder()
-                # build the model and optionally solve
-                rb.build_and_solve(solve=builder_solve)
-                html = rb.get_worker_timetable_html(include_html_tag=True)
-                # store under result so it's accessible from UI
-                result["builder_html"] = html
-                # Persist the HTML on the RotaRun record for easy retrieval
+                worker_count = rota.workers.count()
+            except Exception:
+                worker_count = 0
+
+            if worker_count == 0:
+                result["builder_error"] = "No workers assigned to rota; add workers before running the builder."
+            else:
                 try:
-                    run.export_html = html
-                    run.save(update_fields=["export_html"])
-                except Exception:
-                    # best-effort: if saving fails, include a log entry
-                    run.log = (run.log or "") + "\nFailed to persist export_html"
-            except Exception as exc:
-                # include failure information in run.log and result
-                tb = traceback.format_exc()
-                run.log = (run.log or "") + "\n" + tb
-                result["builder_error"] = str(exc)
+                    # Capture stdout/stderr from the builder so debugging info
+                    # is available in the RotaRun result and log.
+                    out_buf = io.StringIO()
+                    err_buf = io.StringIO()
+                    with contextlib.redirect_stdout(out_buf), contextlib.redirect_stderr(err_buf):
+                        rb = rota.to_rota_builder()
+                        # build the model and optionally solve
+                        rb.build_and_solve(solve=builder_solve)
+                        html = rb.get_worker_timetable_html(include_html_tag=True)
+
+                    # store under result so it's accessible from UI
+                    result["builder_html"] = html
+                    result["builder_stdout"] = out_buf.getvalue()
+                    result["builder_stderr"] = err_buf.getvalue()
+
+                    # Persist the HTML on the RotaRun record for easy retrieval
+                    try:
+                        run.export_html = html
+                        run.save(update_fields=["export_html"])
+                    except Exception:
+                        # best-effort: if saving fails, include a log entry
+                        run.log = (run.log or "") + "\nFailed to persist export_html"
+                    # Append captured output to run.log for convenient viewing
+                    try:
+                        captured = "\n[BUILDER STDOUT]\n" + result.get("builder_stdout", "") + "\n[BUILDER STDERR]\n" + result.get("builder_stderr", "")
+                        run.log = (run.log or "") + captured
+                        # persist the appended log so it is visible to users
+                        # when the run finishes
+                        run.save(update_fields=["log"])
+                    except Exception:
+                        pass
+                except Exception as exc:
+                    # include failure information in run.log and result
+                    tb = traceback.format_exc()
+                    run.log = (run.log or "") + "\n" + tb
+                    result["builder_error"] = str(exc)
 
         run.mark_finished(result=result)