Perform flags validation on save

Issue #540
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/forms.py

@@ -32,6 +32,7 @@ from weblate.trans.models import Unit
 from weblate.trans.models.source import PRIORITY_CHOICES
 from weblate.trans.checks import CHECKS
 from weblate.trans.specialchars import get_special_chars
+from weblate.trans.validators import validate_check_flags
 from weblate.accounts.forms import sort_choices
 from urllib import urlencode
 import weblate
@@ -742,6 +743,17 @@ class CheckFlagsForm(forms.Form):
         )
     )
 
+    def clean_flags(self):
+        """
+        Be a little bit more tolerant on whitespaces.
+        """
+        flags = [
+            x.strip() for x in self.cleaned_data['flags'].strip().split(',')
+        ]
+        flags = ','.join([x for x in flags if x])
+        validate_check_flags(flags)
+        return flags
+
 
 class AddUserForm(forms.Form):
     name = forms.CharField(

weblate/trans/validators.py

@@ -96,6 +96,8 @@ def validate_check_flags(val):
     '''
     Validates check influencing flags.
     '''
+    if not val:
+        return
     for flag in val.split(','):
         if flag in VALID_FLAGS:
             continue