ORM: Add NodeCaching.CACHED_FROM_KEY for _aiida_cached_from constant

The `_aiida_cached_from` key is used to store the UUID, of the node from
which a node was cached, into the extras. It appeared in a few places as
a string literal. It is now added as the `CACHED_FROM_KEY` class
variable of `NodeCaching`.

.github/system_tests/test_daemon.py

@@ -37,6 +37,7 @@
 from aiida.engine.processes import CalcJob, Process
 from aiida.manage.caching import enable_caching
 from aiida.orm import CalcJobNode, Dict, Int, List, Str, load_code, load_node
+from aiida.orm.nodes.caching import NodeCaching
 from aiida.plugins import CalculationFactory, WorkflowFactory
 from aiida.workflows.arithmetic.add_multiply import add, add_multiply
 from tests.utils.memory import get_instances  # pylint: disable=import-error
@@ -207,14 +208,14 @@ def validate_cached(cached_calcs):
             print_report(calc.pk)
             valid = False
 
-        if '_aiida_cached_from' not in calc.base.extras or calc.base.caching.get_hash(
+        if NodeCaching.CACHED_FROM_KEY not in calc.base.extras or calc.base.caching.get_hash(
         ) != calc.base.extras.get('_aiida_hash'):
             print(f'Cached calculation<{calc.pk}> has invalid hash')
             print_report(calc.pk)
             valid = False
 
         if isinstance(calc, CalcJobNode):
-            original_calc = load_node(calc.base.extras.get('_aiida_cached_from'))
+            original_calc = load_node(calc.base.extras.get(NodeCaching.CACHED_FROM_KEY))
             files_original = original_calc.base.repository.list_object_names()
             files_cached = calc.base.repository.list_object_names()
 

aiida/orm/nodes/caching.py

@@ -18,6 +18,7 @@ class NodeCaching:
     # The keys in the extras that are used to store the hash of the node and whether it should be used in caching.
     _HASH_EXTRA_KEY: str = '_aiida_hash'
     _VALID_CACHE_KEY: str = '_aiida_valid_cache'
+    CACHED_FROM_KEY: str = '_aiida_cached_from'
 
     def __init__(self, node: 'Node') -> None:
         """Initialize the caching interface."""
@@ -82,7 +83,7 @@ def get_cache_source(self) -> str | None:
 
         :return: source node UUID or None
         """
-        return self._node.base.extras.get('_aiida_cached_from', None)
+        return self._node.base.extras.get(self.CACHED_FROM_KEY, None)
 
     @property
     def is_created_from_cache(self) -> bool:

aiida/orm/nodes/node.py

@@ -539,7 +539,7 @@ def _store_from_cache(self, cache_node: 'Node') -> None:
 
         self._store(clean=False)
         self._add_outputs_from_cache(cache_node)
-        self.base.extras.set('_aiida_cached_from', cache_node.uuid)
+        self.base.extras.set(self.base.caching.CACHED_FROM_KEY, cache_node.uuid)
 
     def _add_outputs_from_cache(self, cache_node: 'Node') -> None:
         """Replicate the output links and nodes from the cached node onto this node."""

tests/engine/test_process.py

@@ -20,6 +20,7 @@
 from aiida.engine import ExitCode, ExitCodesNamespace, Process, run, run_get_node, run_get_pk
 from aiida.engine.processes.ports import PortNamespace
 from aiida.manage.caching import enable_caching
+from aiida.orm.nodes.caching import NodeCaching
 from aiida.plugins import CalculationFactory
 from tests.utils import processes as test_processes
 
@@ -210,13 +211,13 @@ def test_exit_codes_invalidate_cache(self):
             _, node1 = run_get_node(test_processes.InvalidateCaching, return_exit_code=orm.Bool(False))
             _, node2 = run_get_node(test_processes.InvalidateCaching, return_exit_code=orm.Bool(False))
             assert node1.base.extras.get('_aiida_hash') == node2.base.extras.get('_aiida_hash')
-            assert '_aiida_cached_from' in node2.base.extras
+            assert NodeCaching.CACHED_FROM_KEY in node2.base.extras
 
         with enable_caching():
             _, node3 = run_get_node(test_processes.InvalidateCaching, return_exit_code=orm.Bool(True))
             _, node4 = run_get_node(test_processes.InvalidateCaching, return_exit_code=orm.Bool(True))
             assert node3.base.extras.get('_aiida_hash') == node4.base.extras.get('_aiida_hash')
-            assert '_aiida_cached_from' not in node4.base.extras
+            assert NodeCaching.CACHED_FROM_KEY not in node4.base.extras
 
     def test_valid_cache_hook(self):
         """
@@ -228,13 +229,13 @@ def test_valid_cache_hook(self):
             _, node1 = run_get_node(test_processes.IsValidCacheHook)
             _, node2 = run_get_node(test_processes.IsValidCacheHook)
             assert node1.base.extras.get('_aiida_hash') == node2.base.extras.get('_aiida_hash')
-            assert '_aiida_cached_from' in node2.base.extras
+            assert NodeCaching.CACHED_FROM_KEY in node2.base.extras
 
         with enable_caching():
             _, node3 = run_get_node(test_processes.IsValidCacheHook, not_valid_cache=orm.Bool(True))
             _, node4 = run_get_node(test_processes.IsValidCacheHook, not_valid_cache=orm.Bool(True))
             assert node3.base.extras.get('_aiida_hash') == node4.base.extras.get('_aiida_hash')
-            assert '_aiida_cached_from' not in node4.base.extras
+            assert NodeCaching.CACHED_FROM_KEY not in node4.base.extras
 
     def test_process_type_with_entry_point(self):
         """For a process with a registered entry point, the process_type will be its formatted entry point string."""