157 lines
4.5 KiB
Python
157 lines
4.5 KiB
Python
"""
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Interfaces for serializing Django objects.
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Usage::
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from django.core import serializers
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json = serializers.serialize("json", some_queryset)
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objects = list(serializers.deserialize("json", json))
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To add your own serializers, use the SERIALIZATION_MODULES setting::
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SERIALIZATION_MODULES = {
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"csv": "path.to.csv.serializer",
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"txt": "path.to.txt.serializer",
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}
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"""
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import importlib
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from django.conf import settings
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from django.utils import six
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from django.core.serializers.base import SerializerDoesNotExist
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# Built-in serializers
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BUILTIN_SERIALIZERS = {
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"xml": "django.core.serializers.xml_serializer",
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"python": "django.core.serializers.python",
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"json": "django.core.serializers.json",
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"yaml": "django.core.serializers.pyyaml",
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}
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_serializers = {}
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class BadSerializer(object):
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"""
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Stub serializer to hold exception raised during registration
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This allows the serializer registration to cache serializers and if there
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is an error raised in the process of creating a serializer it will be
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raised and passed along to the caller when the serializer is used.
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"""
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internal_use_only = False
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def __init__(self, exception):
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self.exception = exception
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def __call__(self, *args, **kwargs):
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raise self.exception
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def register_serializer(format, serializer_module, serializers=None):
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"""Register a new serializer.
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``serializer_module`` should be the fully qualified module name
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for the serializer.
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If ``serializers`` is provided, the registration will be added
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to the provided dictionary.
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If ``serializers`` is not provided, the registration will be made
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directly into the global register of serializers. Adding serializers
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directly is not a thread-safe operation.
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"""
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if serializers is None and not _serializers:
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_load_serializers()
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try:
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module = importlib.import_module(serializer_module)
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except ImportError as exc:
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bad_serializer = BadSerializer(exc)
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module = type('BadSerializerModule', (object,), {
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'Deserializer': bad_serializer,
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'Serializer': bad_serializer,
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})
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if serializers is None:
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_serializers[format] = module
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else:
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serializers[format] = module
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def unregister_serializer(format):
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"Unregister a given serializer. This is not a thread-safe operation."
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if not _serializers:
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_load_serializers()
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if format not in _serializers:
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raise SerializerDoesNotExist(format)
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del _serializers[format]
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def get_serializer(format):
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if not _serializers:
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_load_serializers()
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if format not in _serializers:
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raise SerializerDoesNotExist(format)
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return _serializers[format].Serializer
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def get_serializer_formats():
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if not _serializers:
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_load_serializers()
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return list(_serializers)
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def get_public_serializer_formats():
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if not _serializers:
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_load_serializers()
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return [k for k, v in six.iteritems(_serializers) if not v.Serializer.internal_use_only]
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def get_deserializer(format):
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if not _serializers:
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_load_serializers()
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if format not in _serializers:
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raise SerializerDoesNotExist(format)
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return _serializers[format].Deserializer
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def serialize(format, queryset, **options):
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"""
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Serialize a queryset (or any iterator that returns database objects) using
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a certain serializer.
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"""
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s = get_serializer(format)()
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s.serialize(queryset, **options)
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return s.getvalue()
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def deserialize(format, stream_or_string, **options):
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"""
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Deserialize a stream or a string. Returns an iterator that yields ``(obj,
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m2m_relation_dict)``, where ``obj`` is an instantiated -- but *unsaved* --
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object, and ``m2m_relation_dict`` is a dictionary of ``{m2m_field_name :
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list_of_related_objects}``.
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"""
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d = get_deserializer(format)
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return d(stream_or_string, **options)
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def _load_serializers():
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"""
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Register built-in and settings-defined serializers. This is done lazily so
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that user code has a chance to (e.g.) set up custom settings without
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needing to be careful of import order.
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"""
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global _serializers
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serializers = {}
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for format in BUILTIN_SERIALIZERS:
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register_serializer(format, BUILTIN_SERIALIZERS[format], serializers)
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if hasattr(settings, "SERIALIZATION_MODULES"):
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for format in settings.SERIALIZATION_MODULES:
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register_serializer(format, settings.SERIALIZATION_MODULES[format], serializers)
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_serializers = serializers
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