174b4d943a
The comments service rejects whitespace-only content for certain strings, so the discussion API should also reject such content.
38 lines
1.6 KiB
Python
38 lines
1.6 KiB
Python
"""Fields useful for edX API implementations."""
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from django.core.exceptions import ValidationError
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from rest_framework.serializers import CharField, 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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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 field_to_native(self, obj, field_name):
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"""Converts obj to a native representation, using the expanded serializer if the context requires it."""
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if 'expand' in self.context and field_name in self.context['expand']:
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self.expanded.initialize(self, field_name)
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return self.expanded.field_to_native(obj, field_name)
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else:
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self.collapsed.initialize(self, field_name)
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return self.collapsed.field_to_native(obj, field_name)
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class NonEmptyCharField(CharField):
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"""
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A field that enforces non-emptiness even for partial updates.
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This is necessary because prior to version 3, DRF skips validation for empty
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values. Thus, CharField's min_length and RegexField cannot be used to
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enforce this constraint.
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"""
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def validate(self, value):
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super(NonEmptyCharField, self).validate(value)
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if not value.strip():
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raise ValidationError(self.error_messages["required"])
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