RCAL-695 generalize attribute assignment and creation (#284)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: William Jamieson <[email protected]>

CHANGES.rst

@@ -1,7 +1,8 @@
 0.18.1 (unreleased)
 ===================
 
--
+- Allow assignment to or creation of node attributes using dot notation of object instances
+  with validation. [#284]
 
 0.18.0 (2023-11-06)
 ===================

src/roman_datamodels/stnode/_node.py

@@ -94,6 +94,33 @@ def _get_schema_for_property(schema, attr):
     return {}
 
 
+def _get_attributes_from_schema(schema):
+    explicit_properties = schema.get("properties", {}).keys()
+    patterns = schema.get("patternProperties", {})
+    return SchemaProperties(explicit_properties, patterns)
+
+
+class SchemaProperties:
+    """
+    This class provides the capability for using the "contains" machinery
+    so that an attribute can be tested against patternProperties as well
+    as whether the attribute is explicitly a property of the schema.
+    """
+
+    def __init__(self, explicit_properties, patterns):
+        self.explicit_properties = explicit_properties
+        self.patterns = patterns
+
+    def __contains__(self, attr):
+        if attr in self.explicit_properties:
+            return True
+        else:
+            for key in self.patterns.keys():
+                if re.match(key, attr):
+                    return True
+        return False
+
+
 class DNode(MutableMapping):
     """
     Base class describing all "object" (dict-like) data nodes for STNode classes.
@@ -113,6 +140,7 @@ def __init__(self, node=None, parent=None, name=None):
         self._schema_uri = None
         self._parent = parent
         self._name = name
+        self._x_schema_attributes = None
 
     @property
     def ctx(self):
@@ -153,7 +181,7 @@ def __setattr__(self, key, value):
 
         if key[0] != "_":
             value = self._convert_to_scalar(key, value)
-            if key in self._data:
+            if key in self._data or key in self._schema_attributes():
                 if will_validate():
                     schema = _get_schema_for_property(self._schema(), key)
                     if schema:
@@ -164,6 +192,17 @@ def __setattr__(self, key, value):
         else:
             self.__dict__[key] = value
 
+    def _schema_attributes(self):
+        if self._x_schema_attributes is None:
+            self._x_schema_attributes = self._get_schema_attributes()
+        return self._x_schema_attributes
+
+    def _get_schema_attributes(self):
+        """
+        Extract all schema attributes for this node.
+        """
+        return _get_attributes_from_schema(self._schema())
+
     def to_flat_dict(self, include_arrays=True):
         """
         Returns a dictionary of all of the schema items as a flat dictionary.

tests/test_stnode.py

@@ -4,8 +4,12 @@
 import asdf
 import astropy.units as u
 import pytest
+from asdf.exceptions import ValidationError
 
-from roman_datamodels import datamodels, maker_utils, stnode, validate
+from roman_datamodels import datamodels
+from roman_datamodels import maker_utils
+from roman_datamodels import maker_utils as utils
+from roman_datamodels import stnode, validate
 from roman_datamodels.testing import assert_node_equal, assert_node_is_copy, wraps_hashable
 
 from .conftest import MANIFEST
@@ -181,6 +185,26 @@ def test_set_pattern_properties():
     mdl.phot_table.F062.pixelareasr = None
 
 
+# Test that a currently undefined attribute can be assigned using dot notation
+# so long as the attribute is defined in the corresponding schema.
+def test_node_new_attribute_assignment():
+    exp = stnode.Exposure()
+    with pytest.raises(AttributeError):
+        exp.bozo = 0
+    exp.ngroups = 5
+    assert exp.ngroups == 5
+    # Test patternProperties attribute case
+    photmod = utils.mk_wfi_img_photom()
+    phottab = photmod.phot_table
+    newphottab = {"F062": phottab["F062"]}
+    photmod.phot_table = newphottab
+    photmod.phot_table.F213 = phottab["F213"]
+    with pytest.raises(AttributeError):
+        photmod.phot_table.F214 = phottab["F213"]
+    with pytest.raises(ValidationError):
+        photmod.phot_table.F106 = 0
+
+
 VALIDATION_CASES = ("true", "yes", "1", "True", "Yes", "TrUe", "YeS", "foo", "Bar", "BaZ")