Fetch data from two dates query in python and mongoengine

[mahesh d]

Hii
My model like this
class ProcessedEmails(Document):
  subject = StringField(max_length=200)
fromaddress =StringField(max_length=200)
 dateofprocessing = StringField(max_length=25)
How can find out the records between two dates ??
Note: date of processing is string field
 Mongodb database using .
How to write the query in python by using mongoengine

Thanks
Mahesh D.