Data store: fix empty tproxy runtime on reload

Author: MetRonnie

changes.d/6980.fix.md

@@ -0,0 +1 @@
+Fixed a bug where the GUI views would go blank when reloading a workflow.

cylc/flow/commands.py

@@ -609,6 +609,7 @@ async def reload_workflow(schd: 'Scheduler', reload_global: bool = False):
         schd.task_job_mgr.task_remote_mgr.remote_init_map.clear()
         schd.task_job_mgr.task_remote_mgr.is_reload = True
         schd.pool.reload(config)
+        schd.data_store_mgr.apply_task_proxy_db_history()
         # Load jobs from DB
         schd.workflow_db_mgr.pri_dao.select_jobs_for_restart(
             schd.data_store_mgr.insert_db_job

tests/integration/test_reload.py

@@ -19,6 +19,8 @@
 from contextlib import suppress
 
 from cylc.flow import commands
+from cylc.flow.data_store_mgr import TASK_PROXIES
+from cylc.flow.scheduler import Scheduler
 from cylc.flow.task_state import (
     TASK_STATUS_WAITING,
     TASK_STATUS_PREPARING,
@@ -304,3 +306,23 @@ async def test_reload_global_platform_group(
         )
         platform = get_platform(rtconf)
         assert platform['meta']['x'] == '2'
+
+
+async def test_data_store_tproxy(flow, scheduler, start):
+    """Check N>0 task proxy in data store has correct info on reload.
+
+    https://github.com/cylc/cylc-flow/issues/6973
+    """
+    schd: Scheduler = scheduler(flow('foo => bar'))
+
+    def get_ds_tproxy(task):
+        return schd.data_store_mgr.data[schd.id][TASK_PROXIES][
+            f'{schd.id}//1/{task}'
+        ]
+
+    async with start(schd):
+        await schd.update_data_structure()
+        assert str(get_ds_tproxy('bar').runtime)
+
+        await commands.run_cmd(commands.reload_workflow(schd))
+        assert str(get_ds_tproxy('bar').runtime)