misc: avoid crashes when getlist filter not used on a block (#45634)

tests/test_templates.py

@@ -952,3 +952,18 @@ def test_sum():
     assert tmpl.render({'list': None}) == ''   # list is not iterable
     assert tmpl.render({'list': '123'}) == ''  # consider string as not iterable
     assert tmpl.render({}) == ''
+
+
+def test_getlist():
+    class FakeBlock:
+        def getlist(self, key):
+            return {'foo': ['foo1', 'foo2'], 'bar': ['bar1', 'bar2']}[key]
+    tmpl = Template('{% for x in egg|getlist:coin %}{{x}}{% endfor %}')
+    assert tmpl.render({'egg': FakeBlock(), 'coin': 'foo'}) == 'foo1foo2'
+    assert tmpl.render({'egg': FakeBlock(), 'coin': 'bar'}) == 'bar1bar2'
+    tmpl = Template('{{ egg|getlist:"foo"|length }}')
+    assert tmpl.render({'egg': FakeBlock()}) == '2'
+    assert tmpl.render({}) == '0'
+    assert tmpl.render({'egg': None}) == '0'
+    assert tmpl.render({'egg': 'spam'}) == '0'
+    assert tmpl.render({'egg': 42}) == '0'

wcs/qommon/templatetags/qommon.py

@@ -65,6 +65,8 @@ def get(mapping, key):
 
 @register.filter
 def getlist(mapping, key):
+    if not mapping or not hasattr(mapping, 'getlist'):
+        return []
     return mapping.getlist(key)