Change snapshot_directory property to allow GDA to optionally specify…

… it (#1422)

src/hyperion/parameters/components.py

@@ -13,7 +13,7 @@
     TriggerMode,
 )
 from numpy.typing import NDArray
-from pydantic import BaseModel, Extra, Field, validator
+from pydantic import BaseModel, Extra, Field, root_validator, validator
 from scanspec.core import AxesPoints
 from semver import Version
 
@@ -161,17 +161,24 @@ class DiffractionExperiment(HyperionParameters):
     selected_aperture: AperturePositionGDANames | None = Field(default=None)
     ispyb_experiment_type: IspybExperimentType
     storage_directory: str
+    snapshot_directory: Path
+
+    @root_validator(pre=True)
+    def validate_snapshot_directory(cls, values):
+        snapshot_dir = values.get(
+            "snapshot_directory", Path(values["storage_directory"], "snapshots")
+        )
+        values["snapshot_directory"] = (
+            snapshot_dir if isinstance(snapshot_dir, Path) else Path(snapshot_dir)
+        )
+        return values
 
     @property
     def visit_directory(self) -> Path:
         return (
             Path(CONST.I03.BASE_DATA_DIR) / str(datetime.date.today().year) / self.visit
         )
 
-    @property
-    def snapshot_directory(self) -> Path:
-        return Path(self.storage_directory) / "snapshots"
-
     @property
     def num_images(self) -> int:
         return 0

tests/unit_tests/parameters/test_parameter_model.py

@@ -1,4 +1,5 @@
 import json
+from pathlib import Path
 
 import pytest
 from pydantic import ValidationError
@@ -82,3 +83,18 @@ def test_robot_load_then_centre_params():
     test_params = RobotLoadThenCentre(**params)
     assert test_params.visit_directory
     assert test_params.detector_params
+
+
+def test_default_snapshot_path(minimal_3d_gridscan_params):
+    gridscan_params = ThreeDGridScan(**minimal_3d_gridscan_params)
+    assert gridscan_params.snapshot_directory == Path(
+        "/tmp/dls/i03/data/2024/cm31105-4/xraycentring/123456/snapshots"
+    )
+
+    params_with_snapshot_path = dict(minimal_3d_gridscan_params)
+    params_with_snapshot_path["snapshot_directory"] = "/tmp/my_snapshots"
+
+    gridscan_params_with_snapshot_path = ThreeDGridScan(**params_with_snapshot_path)
+    assert gridscan_params_with_snapshot_path.snapshot_directory == Path(
+        "/tmp/my_snapshots"
+    )