烧瓶-WTF 'FileField‘对象没有属性'has_file’

Question

我结合瓶-WTF和烧瓶-上传来处理我的应用程序上的文件上传。

我的包版本是：

Flask-Uploads==0.2.1
Flask-WTF==0.11
WTForms==2.1

下面是我的代码片段：

forms.py

from flask_wtf import Form
from flask_wtf.file import FileAllowed, FileRequired
from wtforms.fields import (StringField, SubmitField, FileField)
from wtforms.validators import InputRequired, Length
from app import photos

class AddCourseForm(Form):
    name = StringField('Course name', validators=[InputRequired(), Length(1, 100)])
    image = FileField('image', validators=[FileRequired(), FileAllowed(photos, 'Images only!')])
    submit = SubmitField('Add course')

下面是上传代码的片段：

@operator.route('/add-course', methods=['GET', 'POST'])
def add_course():
    form = AddCourseForm()
    if form.validate_on_submit():
        course_name = form.name.data
        filename = photos.save(request.files['image'], name="courses/" + course_name + "_course.")
        course = Course(name=course_name, image=filename)
        db.session.add(course)
        db.session.commit()
        flash('Successfully added {} '.format(course.course_name()) + 'course', 'success')
        return redirect(url_for('operator.courses'))
    return render_template('main/operator/add_course.html', form=form)

但是，当我提交时，我得到了以下错误：

AttributeError: 'FileField' object has no attribute 'has_file'

然后，我试图跟踪这个文档，不需要通过直接传递扩展来上传：

image = FileField('image', validators=[FileRequired(), FileAllowed(['jpg', 'png'], 'Images only!')])

但我还是犯了同样的错误。

我的密码怎么了..？如有任何帮助，敬请:)

Answer 1

从wtform库导入FileField：

from wtforms.fields import (StringField, SubmitField, FileField)

..。但是FileField.has_file()方法是特定于Flask-WTF的。

您需要将FileField添加到来自flask_wtf.file的其他导入中。

您可以访问Flask-WTF.file.FileField 这里的API文档。

当前的实现(在这里发现的)是：

class FileField(_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)
        data = next(valuelist, None)

        if data is not None:
            self.data = data
        else:
            self.raw_data = ()

    def has_file(self):
        """Return ``True`` if ``self.data`` is a
        :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 '
            'checked during processing instead.'
        ))
        return bool(self.data)

如您所见，该类继承自标准wtform实现(在模块中名为_FileField )，但将其扩展为覆盖process_formdata()方法并添加has_file()方法。

还请注意，它们正在贬低该方法，并建议您只检查字段的data属性--这并不完全是一种技术实现，因此您可以做他们所做的事情来获得相同的功能：bool(field.data)。

作为参考，下面是wtform FileField实现：

class FileField(Field):
    """Renders a file upload field.
    By default, the value will be the filename sent in the form data.
    WTForms **does not** deal with frameworks' file handling capabilities.
    A WTForms extension for a framework may replace the filename value
    with an object representing the uploaded data.
    """

    widget = widgets.FileInput()

    def _value(self):
        # browser ignores value of file input for security
        return False

...which显示，除了在基类Field类上定义的方法之外，它没有任何方法。