python - Flask WTF表单文件上传：当上传表单继承自另一个表单时，FileRequired() 验证失败，即使文件存在

Question

我有一个收集一些信息的表单，以及一个允许用户上传文件的表单。这些都有效。现在我正在尝试制作一个将它们结合起来并从两者继承的表单。

我的文件上传表单有一个 FileRequired() 验证器。当我只访问上传表单时，这很好。如果我有我的组合表单尝试继承上传表单，验证将失败。但是，如果我删除 FileRequired() 验证器，或者通过从它继承的表单中删除它，或者通过替换组合表单上的该字段，文件上传正常。只有验证失败，而不是文件上传。我可以通过其他方式进行验证（检查 的长度request.files.getlist('<file>')，实际上已经在检查以防止用户上传太多文件，所以我有一个解决方法，但我想了解为什么会失败。

这是我的views.py：

def add_scan(request, exp_id):
    """Add a scan"""
    user_id = str(current_user.get_id())
    if len(request.files.getlist('scan_file')) > 3:
        flash('You can upload up to three files.', 'warning')
        return redirect(url_for('scan.add'))
    for f in request.files.getlist('scan_file'):
        ScanService(user_id, exp_id).add(f)
    flash('You successfully added a new scan.', 'success')
    return redirect(url_for('experiment.experiments'))

@blueprint.route('/add', methods=['GET', 'POST'])
def add():
    """Access the add scan route and form."""
    form = ScanForm()
    if form.validate_on_submit():
        exp_id = str(session['curr_experiment'])
        return add_scan(request, exp_id)
    else:
        flash_errors(form)
    return render_template('scans/upload.html',scan_form=form)

@blueprint.route('/add_experiment_and_scans', methods=['GET', 'POST'])
def add_experiment_and_scans():
    """Acess the add experiment and scans route and form"""
    form = ExperimentAndScanForm(request.form)
    if form.validate_on_submit():
        exp_id = add_experiment(form)
        return add_scan(request, exp_id)
    else:
        flash_errors(form)
    return render_template('scans/experiment_and_scans.html', experiment_and_scan_form=form)

以下是表格：

class ExperimentForm(FlaskForm):
    """Experiment form."""

    date = DateField('Date')

    scanner = SelectField('Scanner', choices=[('GE', 'GE'), ('Sie', 'Siemens'), ('Phi', 'Phillips')])

    field_strength = SelectField('FieldStrength', choices=[('1.5T', '1.5T'), ('3T', '3T'), ('7T', '7T')])

    def __init__(self, *args, **kwargs):
        """Create instance."""
        super(ExperimentForm, self).__init__(*args, **kwargs)

class ScanForm(FlaskForm):
    scan_file = FileField(validators=[FileAllowed(['nii', 'nii.gz', 'zip']), FileRequired()])

    submit = SubmitField('Submit')

    def __init__(self, *args, **kwargs):
        """Create instance."""
        super(ScanForm, self).__init__(*args, **kwargs)

class ExperimentAndScanForm(ExperimentForm, ScanForm):

    def __init__(self, *args, **kwargs):
        """Create instance."""
        super(ExperimentAndScanForm, self).__init__(*args, **kwargs)

验证成功，但ScanForm失败FileRequired()。ExperimentAndScanForm删除（通过从 ScanForm 中删除或替换 中的FileRequired()属性）允许文件上传。在with中创建新属性会导致验证失败。 ExperimentAndScanFormscan_fileExperimentAndScanFormscan_fileExperimentAndScanFormFileRequired()

我不确定它是否有帮助，但这里是呈现此表单的模板：

<form method="POST" action="{{ url_for('scan.add_experiment_and_scans') }}" enctype="multipart/form-data">


   <div class="form-group">
        {{experiment_and_scan_form.date.label}}
        {{experiment_and_scan_form.date(placeholder="Date of session", class_="form-control")}}
    </div>

    <div class="form-group">
        {{experiment_and_scan_form.scanner.label}}
        {{experiment_and_scan_form.scanner(placeholder="Scanner", class_="form-control")}}
    </div>
    <div class="form-group">
        {{experiment_and_scan_form.field_strength.label}}
        {{experiment_and_scan_form.field_strength(placeholder="Field Strength", class_="form-control")}}
    </div>
    {{ experiment_and_scan_form.csrf_token }}
    {{ experiment_and_scan_form.hidden_tag() }}
    {{ experiment_and_scan_form.scan_file(multiple="multiple") }}
    {{ experiment_and_scan_form.submit }}
</form>

标签： pythonflaskfile-uploadflask-wtforms