Form: Raise error for empty field sets

TYPE: Feature
LINK: ogc-1160

src/onegov/form/errors.py

@@ -29,6 +29,11 @@ def __init__(self, line: int):
         self.line = line
 
 
+class EmptyFieldsetError(FormError):
+    def __init__(self, field_name: str):
+        self.field_name = field_name
+
+
 class FieldCompileError(FormError):
     def __init__(self, field_name: str):
         self.field_name = field_name

src/onegov/form/locale/de_ch/LC_MESSAGES/onegov.form.po

@@ -175,6 +175,12 @@ msgstr ""
 "Ein Minimalpreis kann nur gesetzt werden, wenn mindestens ein "
 "kostenpflichtiges Feld definiert ist."
 
+#, python-format
+msgid "The '{label}' group is empty and will not be visible. Either "
+"remove the empty group or add fields to it."
+msgstr "Die Gruppe '{label}' ist leer und wird nicht sichtbar sein. "
+"Entweder entfernen Sie die leere Gruppe oder fügen Felder hinzu."
+
 #, python-format
 msgid ""
 "Invalid field type for field '{label}'. For filters only 'select' or "

src/onegov/form/locale/fr_CH/LC_MESSAGES/onegov.form.po

@@ -174,6 +174,12 @@ msgstr ""
 "Un total de prix minimum ne peut être paramétré que si au moins un champ "
 "payant est défini."
 
+#, python-format
+msgid "The '{label}' group is empty and will not be visible. Either "
+"remove the empty group or add fields to it."
+msgstr "Le groupe '{label}' est vide et ne sera pas visible. Supprimez le "
+"groupe vide ou ajoutez des champs."
+
 #, python-format
 msgid ""
 "Invalid field type for field '{label}'. For filters only 'select' or "

src/onegov/form/locale/it_CH/LC_MESSAGES/onegov.form.po

@@ -172,6 +172,13 @@ msgstr ""
 "È possibile impostare un prezzo minimo totale solo se è definito almeno un "
 "campo prezzo."
 
+#, python-format
+msgid "The '{label}' group is empty and will not be visible. Either "
+"remove the empty group or add fields to it."
+msgstr ""
+"Il gruppo '{label}' è vuoto e non sarà visibile. Rimuovere il gruppo vuoto "
+"o aggiungere campi."
+
 #, python-format
 msgid ""
 "Invalid field type for field '{label}'. For filters only 'select' or "

src/onegov/form/parser/core.py

@@ -1156,18 +1156,19 @@ class CheckboxField(OptionsField, Field):
 @lru_cache(maxsize=1)
 def parse_formcode(
     formcode: str,
-    enable_indent_check: bool = False
+    enable_edit_checks: bool = False
 ) -> list[Fieldset]:
     """ Takes the given formcode and returns an intermediate representation
     that can be used to generate forms or do other things.
 
     :param formcode: string representing formcode to be parsed
-    :param enable_indent_check: bool to activate indent check while parsing.
-        Should only be active originating from forms.validators.py
+    :param enable_edit_checks: bool to activate additional check after
+    editing the form. Should only be active originating from
+    forms.validators.py
     """
     # CustomLoader is inherited from SafeLoader so no security issue here
     parsed = yaml.load(  # nosec B506
-        '\n'.join(translate_to_yaml(formcode, enable_indent_check)),
+        '\n'.join(translate_to_yaml(formcode, enable_edit_checks)),
         CustomLoader
     )
 
@@ -1188,6 +1189,8 @@ def parse_formcode(
             parse_field_block(block, field_classes, used_ids, fs)
             for block in (fieldset[label] or ())
         ]
+        if enable_edit_checks and not fs.fields:
+            raise errors.EmptyFieldsetError(label)
 
         fieldsets.append(fs)
 
@@ -1328,14 +1331,14 @@ def validate_indent(indent: str) -> bool:
 
 def translate_to_yaml(
     text: str,
-    enable_indent_check: bool = False
+    enable_edit_checks: bool = False
 ) -> 'Iterator[str]':
     """ Takes the given form text and constructs an easier to parse yaml
     string.
 
     :param text: string to be parsed
-    :param enable_indent_check: bool to activate indent check while parsing.
-        Should only be active originating from forms.validators.py
+    :param enable_edit_checks: bool to activate additional checks after
+    editing a form. Should only be active originating from forms.validators.py
     """
 
     lines = ((ix, l) for ix, l in prepare(text))
@@ -1352,7 +1355,7 @@ def escape_double(text: str) -> str:
     for ix, line in lines:
 
         indent = ' ' * (4 + (len(line) - len(line.lstrip())))
-        if enable_indent_check and not validate_indent(indent):
+        if enable_edit_checks and not validate_indent(indent):
             raise errors.InvalidIndentSyntax(line=ix + 1)
 
         # the top level are the fieldsets

src/onegov/form/parser/form.py

@@ -54,15 +54,15 @@
 @overload
 def parse_form(
     text: str,
-    enable_indent_check: bool,
+    enable_edit_checks: bool,
     base_class: type[_FormT]
 ) -> type[_FormT]: ...
 
 
 @overload
 def parse_form(
     text: str,
-    enable_indent_check: bool = False,
+    enable_edit_checks: bool = False,
     *,
     base_class: type[_FormT]
 ) -> type[_FormT]: ...
@@ -71,27 +71,28 @@ def parse_form(
 @overload
 def parse_form(
     text: str,
-    enable_indent_check: bool = False,
+    enable_edit_checks: bool = False,
     base_class: type[Form] = Form
 ) -> type[Form]: ...
 
 
 def parse_form(
     text: str,
-    enable_indent_check: bool = False,
+    enable_edit_checks: bool = False,
     base_class: type[Form] = Form
 ) -> type[Form]:
     """ Takes the given form text, parses it and returns a WTForms form
     class (not an instance of it).
 
     :type text: string form text to be parsed
-    :param enable_indent_check: bool to activate indent check while parsing.
+    :param enable_edit_checks: bool to activate additional checks after
+    editing a form.
     :param base_class: Form base class
     """
 
     builder = WTFormsClassBuilder(base_class)
 
-    for fieldset in parse_formcode(text, enable_indent_check):
+    for fieldset in parse_formcode(text, enable_edit_checks):
         builder.set_current_fieldset(fieldset.label)
 
         for field in fieldset.fields:

src/onegov/form/validators.py

@@ -11,7 +11,8 @@
 from dateutil.relativedelta import relativedelta
 from mimetypes import types_map
 from onegov.form import _
-from onegov.form.errors import DuplicateLabelError, InvalidIndentSyntax
+from onegov.form.errors import (DuplicateLabelError, InvalidIndentSyntax,
+                                EmptyFieldsetError)
 from onegov.form.errors import FieldCompileError
 from onegov.form.errors import InvalidFormSyntax
 from onegov.form.errors import MixedTypeError
@@ -190,6 +191,9 @@ class ValidFormDefinition:
         "A minimum price total can only be set if at least one priced field "
         "is defined."
     )
+    empty_fieldset = _(
+        "The '{label}' group is empty and will not be visible. Either remove "
+        "the empty group or add fields to it.")
 
     def __init__(
         self,
@@ -219,6 +223,11 @@ def __call__(self, form: 'Form', field: 'Field') -> 'Form | None':
             raise ValidationError(
                 field.gettext(self.indent).format(line=exception.line)
             ) from exception
+        except EmptyFieldsetError as exception:
+            raise ValidationError(
+                field.gettext(self.empty_fieldset).format(
+                    label=exception.field_name)
+            ) from exception
         except DuplicateLabelError as exception:
             raise ValidationError(
                 field.gettext(self.duplicate).format(label=exception.label)
@@ -305,13 +314,13 @@ def __call__(self, form: 'Form', field: 'Field') -> 'Form | None':
     def _parse_form(
         self,
         field: 'Field',
-        enable_indent_check: bool = True
+        enable_edit_checks: bool = True
     ) -> 'Form':
         # XXX circular import
         from onegov.form import parse_form
 
         return parse_form(field.data,
-                          enable_indent_check=enable_indent_check)()
+                          enable_edit_checks=enable_edit_checks)()
 
 
 class ValidFilterFormDefinition(ValidFormDefinition):

tests/onegov/form/test_parser.py

@@ -1046,7 +1046,7 @@ def test_normalization():
     assert norm == "Ich möchte die Bestellung mittels Post erhalten"
 
 
-@pytest.mark.parametrize('indent,indent_check,shall_raise', [
+@pytest.mark.parametrize('indent,edit_checks,shall_raise', [
     # indent check active while parsing
     ('', True, False),
     (' ', True, True),
@@ -1055,7 +1055,7 @@ def test_normalization():
     # no indent check while parsing
     ('', False, False),
 ])
-def test_indentation_error_while_parsing(indent, indent_check, shall_raise):
+def test_indentation_error(indent, edit_checks, shall_raise):
     # wrong indent see 'Telefonnummer'
     text = dedent(
         """
@@ -1069,11 +1069,57 @@ def test_indentation_error_while_parsing(indent, indent_check, shall_raise):
 
     if shall_raise:
         with pytest.raises(InvalidIndentSyntax) as excinfo:
-            parse_formcode(text, enable_indent_check=indent_check)
+            parse_formcode(text, enable_edit_checks=edit_checks)
 
         assert excinfo.value.line == 6
     else:
         try:
-            parse_formcode(text, enable_indent_check=indent_check)
+            parse_formcode(text, enable_edit_checks=edit_checks)
         except InvalidIndentSyntax as e:
             pytest.fail('Unexpected exception {}'.format(type(e).__name__))
+
+
+def test_empty_fieldset_error():
+    fieldsets = parse_formcode('\n'.join((
+        "# Section 1",
+        "# Section 2",
+        "First Name *= ___",
+        "Last Name *= ___",
+        "E-mail *= @@@"
+    )), enable_edit_checks=False)
+    assert len(fieldsets) == 2
+
+    with pytest.raises(errors.EmptyFieldsetError) as e:
+        parse_formcode('\n'.join((
+            "# Section 1",
+            "# Section 2",
+            "First Name *= ___",
+            "Last Name *= ___",
+            "E-mail *= @@@"
+        )), enable_edit_checks=True)
+
+    assert e.value.field_name == 'Section 1'
+
+    with pytest.raises(errors.EmptyFieldsetError) as e:
+        parse_formcode('\n'.join((
+            "# Section 1",
+            "First Name *= ___",
+            "Last Name *= ___",
+            "# Section 2",
+            "E-mail *= @@@",
+            "# Section 3",
+        )), enable_edit_checks=True)
+
+    assert e.value.field_name == 'Section 3'
+
+    with pytest.raises(errors.EmptyFieldsetError) as e:
+        parse_formcode('\n'.join((
+            "# Section 1",
+            "First Name *= ___",
+            "Last Name *= ___",
+            "# Section 2",
+            "# Section 3",
+            "E-mail *= @@@",
+        )), enable_edit_checks=True)
+
+    assert e.value.field_name == 'Section 2'