FileRequiredValidator() doesn't work when using MultipleFileField() in my form

This works for me (found on GitHub "between the lines"):

multi_file = MultipleFileField("Upload File(s)", validators=[DataRequired()])

However

FileAllowed(["xml", "jpg"])

is ignored and does not work for me.

EDIT:No, sadly, it does not work... It returns True for form.validate() and for form.validate_on_submit() but when you pass no files, by deleting

required=""

from

<input id="multi_file" multiple="" name="multi_file" required="" type="file">

and submit a form, it still evaluate that as True.

So problem sill persist in full, as described...

Regarding FileAllowed validator , it is not working because FileAllowed validator expect one FileStorage object , but MultipleFileField is sending a list of Filestorage objects , which is why it is not working . You have to implement a MultiFileAllowed validator yourself. For More details StackOverflow answer explained with example.

This approach seems to solve the one part of the problem and it uses j-query, which I was unfamiliar with until this point.So since I am a novice when it comes to web-dev, I was looking for a python based approach to this one. I don't think it exists just yet.Will update when I fix the multiple file upload issue.Jsfiddle link

jQuery.validator.setDefaults({  debug: true,  success: "valid"});$( "#myform" ).validate({  rules: {    ":file": {      required: true,      accept: "image/*"    }  }});

and

<form id="myform"><label for="field">Required, image files only: </label><input type="file" class="left" id="field" name="field" multiple><br/><input type="submit" value="Validate!"></form><script src="https://code.jquery.com/jquery-1.11.1.min.js"></script><script src="https://cdn.jsdelivr.net/jquery.validation/1.16.0/jquery.validate.min.js"></script><script src="https://cdn.jsdelivr.net/jquery.validation/1.16.0/additional-methods.min.js"></script>

Since I was using wtforms, I tried something called a validation class and inline validators that seems to do the trick.

 """Validation Class for RoomUpload"""class MyRoomValidator(object):    def __init__(self, message=None):        if not message:            message = u"You need to upload the images with the category as well"        self.message = message    def __call__(self, form, field):        print(len(form.roomImage.data))        print((form.roomTypeSelect.data))        if (not form.roomImage.data and  form.roomTypeSelect.data == -1) or(form.roomImage.data and  form.roomTypeSelect.data == -1) or (not form.roomImage.data and  form.roomTypeSelect.data != -1):#check for all possible combinations            raise ValidationError(self.message)class RoomUpload(FlaskForm):    """    This is meant for the sub-form for room details upload    containing the details for room and its subtype    roomImage:Upload the room image    roomTypeSelect:The subcategory for room category    The Form will only be submitted if the images  are uploaded and    the RoomType will be selected    """    def validate_roomTypeSelect(form, field):#Inline Validator to ensure if default choice is not chosen       print(field.data)       if field.data == -1:            raise ValidationError('Need to Select Room Type')    def validate_roomImage(form,field):        for roomFile in field.data:            print(roomFile.filename)            if  isanImageFile(roomFile.filename) == False:                 raise ValidationError("Error!!! Not an Image File ")    roomImage = MultipleFileField(u"Room",validators=[MyRoomValidator(),FileAllowed],id = "roomImage")    roomTypeSelect= SelectField("Room Type",choices=roomTypes,coerce=int,id="roomTypeSelect")    roomSubmit = SubmitField("Upload the images  of the room")