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85 lines
2.7 KiB
Python
85 lines
2.7 KiB
Python
"""
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Pagination serializers determine the structure of the output that should
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be used for paginated responses.
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"""
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from __future__ import unicode_literals
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from rest_framework import serializers
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from rest_framework.templatetags.rest_framework import replace_query_param
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class NextPageField(serializers.Field):
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"""
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Field that returns a link to the next page in paginated results.
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"""
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page_field = 'page'
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def to_representation(self, value):
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if not value.has_next():
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return None
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page = value.next_page_number()
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request = self.context.get('request')
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url = request and request.build_absolute_uri() or ''
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return replace_query_param(url, self.page_field, page)
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class PreviousPageField(serializers.Field):
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"""
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Field that returns a link to the previous page in paginated results.
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"""
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page_field = 'page'
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def to_representation(self, value):
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if not value.has_previous():
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return None
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page = value.previous_page_number()
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request = self.context.get('request')
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url = request and request.build_absolute_uri() or ''
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return replace_query_param(url, self.page_field, page)
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class DefaultObjectSerializer(serializers.ReadOnlyField):
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"""
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If no object serializer is specified, then this serializer will be applied
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as the default.
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"""
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def __init__(self, source=None, many=None, context=None):
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# Note: Swallow context and many kwargs - only required for
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# eg. ModelSerializer.
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super(DefaultObjectSerializer, self).__init__(source=source)
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class BasePaginationSerializer(serializers.Serializer):
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"""
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A base class for pagination serializers to inherit from,
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to make implementing custom serializers more easy.
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"""
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results_field = 'results'
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def __init__(self, *args, **kwargs):
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"""
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Override init to add in the object serializer field on-the-fly.
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"""
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super(BasePaginationSerializer, self).__init__(*args, **kwargs)
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results_field = self.results_field
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try:
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object_serializer = self.Meta.object_serializer_class
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except AttributeError:
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object_serializer = DefaultObjectSerializer
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self.fields[results_field] = serializers.ListSerializer(
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child=object_serializer(),
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source='object_list'
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)
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self.fields[results_field].bind(results_field, self, self)
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class PaginationSerializer(BasePaginationSerializer):
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"""
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A default implementation of a pagination serializer.
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"""
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count = serializers.ReadOnlyField(source='paginator.count')
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next = NextPageField(source='*')
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previous = PreviousPageField(source='*')
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