35 lines
1.5 KiB
Python
35 lines
1.5 KiB
Python
"""Fields useful for edX API implementations."""
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from rest_framework.serializers import Field
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class ExpandableField(Field):
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"""Field that can dynamically use a more detailed serializer based on a user-provided "expand" parameter.
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Kwargs:
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collapsed_serializer (Serializer): the serializer to use for a non-expanded representation.
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expanded_serializer (Serializer): the serializer to use for an expanded representation.
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"""
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def __init__(self, **kwargs):
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"""Sets up the ExpandableField with the collapsed and expanded versions of the serializer."""
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assert 'collapsed_serializer' in kwargs and 'expanded_serializer' in kwargs
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self.collapsed = kwargs.pop('collapsed_serializer')
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self.expanded = kwargs.pop('expanded_serializer')
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super(ExpandableField, self).__init__(**kwargs)
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def to_representation(self, obj):
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"""
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Return a representation of the field that is either expanded or collapsed.
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"""
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should_expand = self.field_name in self.context.get("expand", [])
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field = self.expanded if should_expand else self.collapsed
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# Avoid double-binding the field, otherwise we'll get
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# an error about the source kwarg being redundant.
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if field.source is None:
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field.bind(self.field_name, self)
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if should_expand:
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self.expanded.context["expand"] = set(field.context.get("expand", []))
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return field.to_representation(obj)
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