Fix malformed error message when creating invalid Realm Emoji.

Thanks to Greg McCoy for his help finding this bug.

tools/lint-all

@@ -193,7 +193,7 @@ python_rules = [
           'return json_error(data=error_data, msg=ret_error)'),
          ('zerver/views/streams.py', 'return json_error(property_conversion)'),
          # We can't do anything about this.
-         ('zerver/views/realm_emoji.py', 'return json_error(e.message_dict)'),
+         ('zerver/views/realm_emoji.py', 'return json_error(e.messages[0])'),
      ]),
      'description': 'Argument to json_error should a literal string enclosed by _()'},
     # To avoid JsonableError(_variable) and JsonableError(_(variable))

zerver/models.py

@@ -25,6 +25,7 @@
 from zerver.lib.timestamp import datetime_to_timestamp
 from django.db.models.signals import pre_save, post_save, post_delete
 from django.core.validators import MinLengthValidator, RegexValidator
+from django.utils.translation import ugettext as _
 import zlib
 
 from bitfield import BitField
@@ -243,7 +244,8 @@ class RealmEmoji(models.Model):
     realm = models.ForeignKey(Realm)
     # Second part of the regex (negative lookbehind) disallows names ending with one of the punctuation characters
     name = models.TextField(validators=[MinLengthValidator(1),
-                                        RegexValidator(regex=r'^[0-9a-zA-Z.\-_]+(?<![.\-_])$')])
+                                        RegexValidator(regex=r'^[0-9a-zA-Z.\-_]+(?<![.\-_])$',
+                                                       message=_("Invalid characters in Emoji name"))])
     # URLs start having browser compatibility problem below 2000
     # characters, so 1000 seems like a safe limit.
     img_url = models.URLField(max_length=1000)

zerver/views/realm_emoji.py

@@ -23,7 +23,7 @@ def upload_emoji(request, user_profile):
     try:
         check_add_realm_emoji(user_profile.realm, emoji_name, emoji_url)
     except ValidationError as e:
-        return json_error(e.message_dict)
+        return json_error(e.messages[0])
     return json_success()
 
 def delete_emoji(request, user_profile, emoji_name):