open-eats/openeats-api

#!/usr/bin/env python
# encoding: utf-8


class FieldLimiter(object):
    """
    Custom Mixing that allows limiting tha amount of data that is returned.
    A lot of the time I only need some of the data a model has available.
    Usage:
        Add this mixin to a serializer.
        In the query string add `fields={ fields needed }`
        Example `fields=title,date,owner`
    """
    def __init__(self, *args, **kwargs):
        # Instantiate the superclass normally
        super(FieldLimiter, self).__init__(*args, **kwargs)

        if 'request' in self.context:
            fields = self.context['request'].query_params.get('fields')
            if fields:
                fields = fields.split(',')
                # Drop any fields that are not specified in the `fields` argument.
                allowed = set(fields)
                existing = set(self.fields.keys())
                for field_name in existing - allowed:
                    self.fields.pop(field_name)