Adding PyDF (Python Display Filters) matcher.

Author: chsou

c8y_api/model/matcher/__init__.py

@@ -38,6 +38,14 @@
     'command',
 ]
 
+try:
+    import pydictdisplayfilter as _pydictdisplayfilter
+    from ._pydf_matcher import PydfMatcher, pydf
+    __all__.append('PydfMatcher')
+    __all__.append('pydf')
+except ImportError:
+    pass
+
 try:
     import jmespath as _jmespath
     from ._jmespath_matcher import JmesPathMatcher, jmespath

c8y_api/model/matcher/_pydf_matcher.py

@@ -0,0 +1,23 @@
+# Copyright (c) 2025 Cumulocity GmbH
+
+from pydictdisplayfilter.display_filters import DictDisplayFilter
+
+from c8y_api.model.matcher._matcher import JsonMatcher
+
+
+class PydfMatcher(JsonMatcher):
+    """JsonMatcher implementation for JMESPath."""
+
+    def __init__(self, expression: str, warn_on_error: bool = True):
+        super().__init__(expression, warn_on_error)
+        self.display_filter = DictDisplayFilter([])
+        self.compiled_expression = self.display_filter._display_filter_parser.parse(expression)
+
+    def matches(self, json: dict) -> bool:
+        # pylint: disable=broad-exception-caught
+        return self.display_filter._evaluate_expressions(self.compiled_expression, json)
+
+
+def pydf(expression: str) -> PydfMatcher:
+    """Create a PydfMatcher from an expression."""
+    return PydfMatcher(expression)

pyproject.toml

@@ -34,9 +34,10 @@ dependencies = [
 ]
 
 [project.optional-dependencies]
+pydf = ["python-dict-display-filter"]
 jmespath = ["jmespath"]
 jsonpath = ["jsonpath-ng"]
-filters = ["jmespath", "jsonpath-ng"]
+filters = ["python-dict-display-filter", "jmespath", "jsonpath-ng"]
 
 [project.urls]
 Homepage = "https://github.com/Cumulocity-IoT/cumulocity-python-api"

tests/model/test_matchers.py

@@ -169,6 +169,20 @@ def test_command_matcher():
         matches_mock.assert_not_called()
 
 
+def test_pydf_matcher():
+    """Verify that the pydf matchers work as expected."""
+    assert pydf("name == NAME").matches({'name': 'NAME'})
+    assert pydf("name[0:2] eq NA").matches({'name': 'NAME'})
+    assert pydf("name contains AM").matches({'name': 'NAME'})
+    assert pydf("name in  {'NAME', 'NONAME'}").matches({'name': 'NAME'})
+    assert pydf("lower(name) == name").matches({'name': 'NAME'})
+    assert pydf("len(name) == 4").matches({'name': 'NAME'})
+    assert not pydf("name == 'NAME'").matches({'name': 'RANDOM'})
+    with pytest.raises(Exception) as error:
+        pydf("*INVALID*").matches({})
+    assert "Error parsing display filter" in str(error.value)
+
+
 def test_jmespath_matcher():
     """Verify that the jmespath matchers work as expected."""
     assert jmespath("name == 'NAME'").matches({'name': 'NAME'})
@@ -177,7 +191,6 @@ def test_jmespath_matcher():
         jmespath("*INVALID*").matches({})
     assert "INVALID" in str(error.value)
 
-# $[?(@.firstName == "John")]
 
 def test_jsonpath_matcher():
     """Verify that the jsonpath matchers work as expected."""