templates: add sum filter (#45394)

tests/test_formdata.py

@@ -2314,3 +2314,13 @@ def test_block_variables(pub, blocks_feature):
 
     tmpl = Template('{% for foo in form_var_block|getlist:"foo" %}/{{ foo }}{% endfor %}')
     assert tmpl.render(context) == '/foo/foo2'
+
+    formdata.data = {
+        '1': {
+            'data': [{'123': '2', '234': '2'}, {'123': '7', '234': 'bla'}],
+            'schema': {'123': 'string', '234': 'string'}
+            },
+    }
+    formdata.store()
+    tmpl = Template('{{ form_var_block|getlist:"foo"|sum }} {{ form_var_block|getlist:"bar"|sum }}')
+    assert tmpl.render(context) == '9 2'

tests/test_templates.py

@@ -939,3 +939,16 @@ def test_adjust_to_working_day_weekend(settings):
     assert t.render({'value': '2020-06-20'}) == '2020-06-22'
     t = Template('{{ value|adjust_to_working_day_with_saturday }}')
     assert t.render({'value': '2020-06-20'}) == '2020-06-20'
+
+
+def test_sum():
+    tmpl = Template('{{ "2 29.5 9,5 .5"|split|sum }}')
+    assert tmpl.render({}) == '41.5'
+    tmpl = Template('{{ list|sum }}')
+    assert tmpl.render({'list': [1, 2, '3']}) == '6'
+    assert tmpl.render({'list': [1, 2, 'x']}) == '3'
+    assert tmpl.render({'list': [None, 2.0, 'x']}) == '2'
+    assert tmpl.render({'list': []}) == '0'
+    assert tmpl.render({'list': None}) == ''   # list is not iterable
+    assert tmpl.render({'list': '123'}) == ''  # consider string as not iterable
+    assert tmpl.render({}) == ''

wcs/qommon/templatetags/qommon.py

@@ -437,6 +437,19 @@ def divide(term1, term2):
         return ''
 
 
+@register.filter(name='sum')
+def sum_(list_):
+    if hasattr(list_, 'get_value'):
+        list_ = list_.get_value()  # unlazy
+    if isinstance(list_, six.string_types):
+        # do not consider string as iterable, to avoid misusage
+        return ''
+    try:
+        return sum(parse_decimal(term) for term in list_)
+    except TypeError:  # list_ is not iterable
+        return ''
+
+
 @register.filter
 def ceil(value):
     '''the smallest integer value greater than or equal to value'''