feat(jexl): add length transform

caluma/caluma_core/jexl.py

@@ -75,6 +75,7 @@ def __init__(self, *args, **kwargs):
         self.add_transform("mapby", self._mapby_transform)
         self.add_transform("stringify", lambda obj: json.dumps(obj))
         self.add_transform("flatten", self._flatten_transform)
+        self.add_transform("length", self._length_transform)
         self.add_binary_operator(
             "intersects", 20, lambda left, right: any(x in right for x in left)
         )
@@ -159,6 +160,12 @@ def _flatten_transform(self, arr, *options):
 
         return list(chain(*arr))
 
+    def _length_transform(self, value, *options):
+        try:
+            return len(value)
+        except TypeError:
+            return None
+
     def evaluate(self, expression, context=None):
         self._expr_stack.append(expression)
         try:

caluma/caluma_core/tests/test_jexl.py

@@ -194,6 +194,13 @@ def test_intersects_operator(expression, result):
             ["some-value", "some-other-value"],
         ),
         ("null|flatten", None),
+        # count
+        ("['test1', 'test2']|length", 2),
+        ("{key: 1}|length", 1),
+        ("'foobar'|length", 6),
+        ("1|length", None),
+        ("1.1|length", None),
+        ("null|length", None),
     ],
 )
 def test_simple_transforms(expression, result):