Fix add corpus file form

app/corpora/forms.py

@@ -20,15 +20,15 @@ class AddCorpusFileForm(FlaskForm):
     title = StringField('Title', validators=[InputRequired(), Length(1, 255)])
     vrt = FileField('File', validators=[FileRequired()])
     # Optional fields
-    address = StringField('Adress', validators=[Length(255)])
-    booktitle = StringField('Booktitle', validators=[Length(255)])
-    chapter = StringField('Chapter', validators=[Length(255)])
-    editor = StringField('Editor', validators=[Length(255)])
-    institution = StringField('Institution', validators=[Length(255)])
-    journal = StringField('Journal', validators=[Length(255)])
-    pages = StringField('Pages', validators=[Length(255)])
-    publisher = StringField('Publisher', validators=[Length(255)])
-    school = StringField('School', validators=[Length(255)])
+    address = StringField('Adress', validators=[Length(0, 255)])
+    booktitle = StringField('Booktitle', validators=[Length(0, 255)])
+    chapter = StringField('Chapter', validators=[Length(0, 255)])
+    editor = StringField('Editor', validators=[Length(0, 255)])
+    institution = StringField('Institution', validators=[Length(0, 255)])
+    journal = StringField('Journal', validators=[Length(0, 255)])
+    pages = StringField('Pages', validators=[Length(0, 255)])
+    publisher = StringField('Publisher', validators=[Length(0, 255)])
+    school = StringField('School', validators=[Length(0, 255)])
     submit = SubmitField()
 
     def validate_vrt(self, field):