form: correctly ignore empty values in WidgetList (#8866)

(it used to ignore None but we also want it to ignore '')

tests/test_admin_pages.py

@@ -877,6 +877,46 @@ def test_form_edit_field_advanced(pub):
     assert resp.body.index('<legend>Additional parameters</legend>') > \
             resp.body.index('<label for="form_data_source">Data Source</label>')
 
+def test_form_edit_item_field(pub):
+    create_superuser(pub)
+    create_role()
+
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'form title'
+    formdef.fields = [fields.ItemField(id='1', label='1st field', type='item')]
+    formdef.store()
+
+    app = login(get_app(pub))
+    resp = app.get('/backoffice/forms/1/')
+    resp = resp.click(href='fields/')
+    assert '1st field' in resp.body
+
+    resp = resp.click('Edit', href='1/')
+    assert resp.forms[0]['label'].value == '1st field'
+    resp.forms[0]['label'] = 'changed field'
+    resp.forms[0]['required'] = False
+    resp = resp.forms[0].submit('items$add_element')
+    # this adds a second field
+    assert 'items$element0' in resp.form.fields
+    assert 'items$element1' in resp.form.fields
+    # but don't fill anything
+    resp = resp.forms[0].submit('submit')
+    assert resp.location == 'http://example.net/backoffice/forms/1/fields/'
+    resp = resp.follow()
+
+    assert FormDef.get(1).fields[0].label == 'changed field'
+    assert FormDef.get(1).fields[0].required == False
+    assert FormDef.get(1).fields[0].items is None
+
+    # edit and fill with one item
+    resp = resp.click('Edit', href='1/')
+    assert resp.forms[0]['label'].value == 'changed field'
+    resp.forms[0]['items$element0'] = 'XXX'
+    resp = resp.forms[0].submit('submit')
+    assert resp.location == 'http://example.net/backoffice/forms/1/fields/'
+    assert FormDef.get(1).fields[0].items == ['XXX']
+
 def test_form_legacy_int_id(pub):
     create_superuser(pub)
     create_role()

wcs/qommon/form.py

@@ -1179,6 +1179,15 @@ class WidgetList(quixote.form.widget.WidgetList):
         r += self.render_hint(self.get_hint())
         return r.getvalue()
 
+    def _parse(self, request):
+        values = []
+        for name in self.element_names:
+            value = self.get(name)
+            if value:
+                values.append(value)
+        self.value = values or None
+
+
 class WidgetDict(quixote.form.widget.WidgetDict):
     # Fix the title and hint setting
     # FIXME: to be fixed in Quixote upstream : title and hint parameters should be removed