don't assume Form meta arg is not None

closes #278

docs/api.rst

@@ -19,7 +19,8 @@ Forms and Fields
 
 .. module:: flask_wtf.file
 
-.. autoclass:: FileField(...)
+.. autoclass:: FileField
+    :members: has_file
 
 .. autoclass:: FileAllowed
 

docs/changelog.rst

@@ -1,6 +1,16 @@
 Flask-WTF Changelog
 ===================
 
+Version 0.14.2
+--------------
+
+Released 2017-01-10
+
+- Fix bug where ``FlaskForm`` assumed ``meta`` argument was not ``None`` if it
+  was passed. (`#278`_)
+
+.. _#278: https://github.com/lepture/flask-wtf/issues/278
+
 Version 0.14.1
 --------------
 

docs/form.rst

@@ -30,6 +30,30 @@ File Uploads
 
 .. module:: flask_wtf.file
 
+The :class:`FileField` provided by Flask-WTF differs from the WTForms-provided
+field. It will check that the file is a non-empty instance of
+:class:`~werkzeug.datastructures.FileStorage`, otherwise ``data`` will be
+``None``. ::
+
+    from flask_wtf import FlaskForm
+    from flask_wtf.file import FileField, FileRequired
+    from werkzeug.utils import secure_filename
+
+    class PhotoForm(FlaskForm):
+        photo = FileField(validators=[FileRequired()])
+
+    @app.route('/upload', methods=['GET', 'POST'])
+    def upload():
+        if form.validate_on_submit():
+            f = form.photo.data
+            filename = secure_filename(f.filename)
+            f.save(os.path.join(
+                app.instance_path, 'photos', filename
+            ))
+            return redirect(url_for('index'))
+
+        return render_template('upload.html', form=form)
+
 Remember to set the ``enctype`` of the HTML form to
 ``multipart/form-data``, otherwise ``request.files`` will be empty.
 
@@ -55,7 +79,8 @@ Validation
 ~~~~~~~~~~
 
 Flask-WTF supports validating file uploads with
-:class:`FileRequired` and :class:`FileAllowed`.
+:class:`FileRequired` and :class:`FileAllowed`. They can be used with both
+Flask-WTF's and WTForms's ``FileField`` classes.
 
 :class:`FileAllowed` works well with Flask-Uploads. ::
 

flask_wtf/file.py

@@ -9,7 +9,7 @@
 
 
 class FileField(_FileField):
-    """Werkzeug-aware subclass of **wtforms.FileField**"""
+    """Werkzeug-aware subclass of :class:`wtforms.fields.FileField`."""
 
     def process_formdata(self, valuelist):
         valuelist = (x for x in valuelist if isinstance(x, FileStorage) and x)
@@ -22,7 +22,12 @@ def process_formdata(self, valuelist):
 
     def has_file(self):
         """Return ``True`` if ``self.data`` is a
-        :class:`~werkzeug.datastructures.FileStorage` object."""
+        :class:`~werkzeug.datastructures.FileStorage` object.
+
+        .. deprecated:: 0.14.1
+            ``data`` is no longer set if the input is not a non-empty
+            ``FileStorage``. Check ``form.data is not None`` instead.
+        """
 
         warnings.warn(FlaskWTFDeprecationWarning(
             '"has_file" is deprecated and will be removed in 1.0. The data is '