pythonmongoengine

mongoengine default value from another field

I'm trying out MongoEngine for a project and its quite good. I was wondering if it is possible to set a default value for a field from another field? Something like this

import mongoengine as me

class Company(me.Document):
    short_name = me.StringField(required=True)
    full_name = me.StringField(required=True, default=short_name)

this fails with an error ValidationError (Company:None) (StringField only accepts string values: ['full_name'])

:EDIT:

I did not mention that my app has a service layer which enabled me to simply do it like this:

if company_data['short_name'] is None:
            myCompany.full_name = company_data['short_name']


        obj = myCompany.save()

and it works quite nicely.

Solution

  • You can override save() method on a Document:

    class Company(me.Document):
    short_name = me.StringField(required=True)
    full_name = me.StringField()

    def save(self, *args, **kwargs):
        if not self.full_name:
            self.full_name = self.short_name

        return super(Company, self).save(*args, **kwargs)