95 lines
2.7 KiB
Python
95 lines
2.7 KiB
Python
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"""
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XXX. Serialization
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``django.core.serializers`` provides interfaces to converting Django querysets
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to and from "flat" data (i.e. strings).
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"""
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from django.db import models
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class Category(models.Model):
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name = models.CharField(maxlength=20)
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class Meta:
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ordering = ('name',)
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def __str__(self):
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return self.name
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class Author(models.Model):
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name = models.CharField(maxlength=20)
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class Meta:
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ordering = ('name',)
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def __str__(self):
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return self.name
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class Article(models.Model):
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author = models.ForeignKey(Author)
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headline = models.CharField(maxlength=50)
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pub_date = models.DateTimeField()
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categories = models.ManyToManyField(Category)
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class Meta:
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ordering = ('pub_date',)
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def __str__(self):
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return self.headline
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API_TESTS = """
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# Create some data:
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>>> from datetime import datetime
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>>> sports = Category(name="Sports")
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>>> music = Category(name="Music")
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>>> op_ed = Category(name="Op-Ed")
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>>> sports.save(); music.save(); op_ed.save()
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>>> joe = Author(name="Joe")
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>>> jane = Author(name="Jane")
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>>> joe.save(); jane.save()
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>>> a1 = Article(
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... author = jane,
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... headline = "Poker has no place on ESPN",
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... pub_date = datetime(2006, 6, 16, 11, 00))
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>>> a2 = Article(
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... author = joe,
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... headline = "Time to reform copyright",
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... pub_date = datetime(2006, 6, 16, 13, 00))
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>>> a1.save(); a2.save()
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>>> a1.categories = [sports, op_ed]
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>>> a2.categories = [music, op_ed]
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# Serialize a queryset to XML
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>>> from django.core import serializers
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>>> xml = serializers.serialize("xml", Article.objects.all())
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# The output is valid XML
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>>> from xml.dom import minidom
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>>> dom = minidom.parseString(xml)
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# Deserializing has a similar interface, except that special DeserializedObject
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# instances are returned. This is because data might have changed in the
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# database since the data was serialized (we'll simulate that below).
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>>> for obj in serializers.deserialize("xml", xml):
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... print obj
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<DeserializedObject: Poker has no place on ESPN>
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<DeserializedObject: Time to reform copyright>
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# Deserializing data with different field values doesn't change anything in the
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# database until we call save():
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>>> xml = xml.replace("Poker has no place on ESPN", "Poker has no place on television")
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>>> objs = list(serializers.deserialize("xml", xml))
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# Even those I deserialized, the database hasn't been touched
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>>> Article.objects.all()
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[<Article: Poker has no place on ESPN>, <Article: Time to reform copyright>]
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# But when I save, the data changes as you might except.
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>>> objs[0].save()
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>>> Article.objects.all()
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[<Article: Poker has no place on television>, <Article: Time to reform copyright>]
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"""
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