use InputRequired() validators

prolefeeder.py

@@ -3,7 +3,7 @@ from flask import (Flask, render_template, flash, redirect,
 from flask_bootstrap import Bootstrap
 from flask_wtf import FlaskForm
 from wtforms import DateTimeField, IntegerField, SubmitField
-from wtforms.validators import DataRequired, NumberRange
+from wtforms.validators import InputRequired, NumberRange
 
 from datetime import datetime, timedelta
 import os
@@ -20,9 +20,9 @@ Bootstrap(app)
 
 
 class DownloadForm(FlaskForm):
-    start_time = DateTimeField('Start time', validators=[DataRequired()],
+    start_time = DateTimeField('Start time', validators=[InputRequired()],
                                format='%Y-%m-%d %H:%M')
-    length = IntegerField('Length', validators=[DataRequired(),
+    length = IntegerField('Length', validators=[InputRequired(),
                                                 NumberRange(min=1, max=app.config['MAX_LENGTH'])])
     submit = SubmitField('Download')