feat(jexl): improve mapby and add stringify transform

This extends the mapby transform to accept multiple keys as argument
which then returns an array instead of the single value. This will
result in nested arrays which is why we added a stringify transform that
converts such a collection into a string to be used in comparisons.

caluma/caluma_core/jexl.py

@@ -1,3 +1,4 @@
+import json
 import math
 import numbers
 from functools import partial
@@ -71,9 +72,8 @@ def __init__(self, *args, **kwargs):
         self.add_transform("debug", self._debug_transform)
         self._expr_stack = []
 
-        self.add_transform(
-            "mapby", lambda arr, key: [obj.get(key, None) for obj in arr]
-        )
+        self.add_transform("mapby", self._mapby_transform)
+        self.add_transform("stringify", lambda obj: json.dumps(obj))
         self.add_binary_operator(
             "intersects", 20, lambda left, right: any(x in right for x in left)
         )
@@ -143,6 +143,15 @@ def _debug_transform(self, value, label=None):
         )
         return value
 
+    def _mapby_transform(self, arr, *keys):
+        if not isinstance(arr, list):
+            return None
+
+        return [
+            [obj.get(key) for key in keys] if len(keys) > 1 else obj.get(keys[0])
+            for obj in arr
+        ]
+
     def evaluate(self, expression, context=None):
         self._expr_stack.append(expression)
         try:
@@ -218,8 +227,9 @@ def visit_Transform(self, transform):
                 and transform.subject
                 and transform.subject.name == "answer"
                 and len(transform.args)
-                and isinstance(transform.args[0], Literal)
             ):
-                yield transform.args[0].value
+                for arg in transform.args:
+                    if isinstance(arg, Literal):
+                        yield arg.value
 
         yield from self.generic_visit(transform)

caluma/caluma_core/tests/test_jexl.py

@@ -111,6 +111,8 @@ def test_jexl_cache():
         ("[{ key: 1 }]|mapby('key')", [1]),
         ("[{ otherkey: 1 }]|mapby('key')", [None]),
         ("[]|mapby('key')", []),
+        ("[{ a: 1, b: 2 }]|mapby('a', 'b', 'c')", [[1, 2, None]]),
+        ("0|mapby('key')", None),
     ],
 )
 def test_mapby_operator(expression, result):
@@ -191,6 +193,17 @@ def test_math_transforms(expression, result):
     assert JEXL().evaluate(expression) == result
 
 
+@pytest.mark.parametrize(
+    "expression,result",
+    [
+        ("[['test1', 'test2'], [1,2]]|stringify", '[["test1", "test2"], [1, 2]]'),
+        ("1|stringify", "1"),
+    ],
+)
+def test_stringify_transform(expression, result):
+    assert JEXL().evaluate(expression) == result
+
+
 @pytest.mark.parametrize(
     "expression,expected",
     [

caluma/caluma_form/tests/test_question.py

@@ -961,9 +961,9 @@ def test_calculated_question(
         ("'table'|answer|mapby('column')[0]", 99.99, ["table", "column"]),
         ("'other'|answer", 3.0, ["other"]),
         (
-            "'sub_question'|answer && 'table'|answer|mapby('column') ? 'other'|answer: -1",
+            "'sub_question'|answer && 'table'|answer|mapby('column', 'column2') ? 'other'|answer: -1",
             3.0,
-            ["sub_question", "table", "column", "other"],
+            ["sub_question", "table", "column", "column2", "other"],
         ),
     ],
 )
@@ -972,6 +972,7 @@ def test_nested_calculated_question(
     schema_executor,
     form_and_document,
     form_question_factory,
+    question_factory,
     expr,
     expected,
     calc_deps,
@@ -993,6 +994,13 @@ def test_nested_calculated_question(
         form=form, question__slug="other", question__type=models.Question.TYPE_INTEGER
     ).question
 
+    questions["column2"] = question_factory(
+        slug="column2", is_required="false", is_hidden="false"
+    )
+    form_question_factory(
+        form=questions["table"].row_form, question=questions["column2"]
+    )
+
     api.save_answer(question=questions["other"], document=document, value=3)
 
     questions["calc"] = form_question_factory(