Add locales as a property to FlaskForm.Meta

.gitignore

@@ -17,3 +17,4 @@ _build
 .idea/
 htmlcov/
 .cache/
+.vscode/

flask_wtf/form.py

@@ -12,7 +12,7 @@
 from .csrf import _FlaskFormCSRF
 
 try:
-    from .i18n import translations
+    from .i18n import translations, get_locale
 except ImportError:
     translations = None  # babel not installed
 
@@ -33,6 +33,13 @@ class Meta(DefaultMeta):
         csrf_class = _FlaskFormCSRF
         csrf_context = session  # not used, provided for custom csrf_class
 
+        @property
+        def locales(self):
+            if not current_app.config.get('WTF_I18N_ENABLED', True):
+                return False
+            locale = get_locale()
+            return [locale.language]
+
         @cached_property
         def csrf(self):
             return current_app.config.get('WTF_CSRF_ENABLED', True)

tests/test_i18n.py

@@ -1,7 +1,7 @@
 # coding=utf8
 import pytest
 from flask import request
-from wtforms import StringField
+from wtforms import StringField, DecimalField
 from wtforms.validators import DataRequired, Length
 
 from flask_wtf import FlaskForm
@@ -72,3 +72,30 @@ def test_outside_request():
     sp = 'Field must be at least %(min)d character long.'
     assert translations.ngettext(ss, sp, 1) == ss
     assert translations.ngettext(ss, sp, 2) == sp
+
+
+class NumberForm(FlaskForm):
+
+    number = DecimalField(use_locale=True)
+
+
+def test_decimal_field_localization(app):
+    try:
+        from flask_babel import Babel
+    except ImportError:
+        try:
+            from flask_babelex import Babel
+        except ImportError:
+            pytest.skip('Flask-Babel or Flask-BabelEx must be installed.')
+
+    Babel(app)
+
+    with app.test_request_context():
+        app.config['BABEL_DEFAULT_LOCALE'] = 'de'
+        form = NumberForm(number=1100.1)
+        assert form['number']._value() == '1.100,1'
+
+    with app.test_request_context():
+        app.config['BABEL_DEFAULT_LOCALE'] = 'en'
+        form = NumberForm(number=1100.1)
+        assert form['number']._value() == '1,100.1'