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DjangoItem

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.. module:: scrapy.contrib_exp.djangoitem

:class:`DjangoItem` is a class of item that gets its fields definition from a Django model, you simply create a :class:`DjangoItem` and specify what Django model it relates to.

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Besides of getting the model fields defined on your item, :class:`DjangoItem` provides a method to create and populate a Django model instance with the item data.

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Using DjangoItem

:class:`DjangoItem` works much like ModelForms in Django, you create a subclass and define its django_model atribute to ve a valid Django model. With this you will get an item with a field for each Django model field.

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In addition, you can define fields that aren't present in the model and even override fields that are present in the model defining them in the item.

Let's see some examples:

Django model for the examples:

class Person(models.Model):
    name = models.CharField(max_length=255)
    age = models.IntegerField()

Defining a basic :class:`DjangoItem`:

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class PersonItem(DjangoItem):
    django_model = Person

:class:`DjangoItem` work just like :class:`~scrapy.item.Item`:

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p = PersonItem()
p['name'] = 'John'
p['age'] = '22'

To obtain the Django model from the item, we call the extra method :meth:`~DjangoItem.save` of the :class:`DjangoItem`:

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>>> person = p.save()
>>> person.name
'John'
>>> person.age
'22'
>>> person.id
1

As you see the model is already saved when we call :meth:`~DjangoItem.save`, we can prevent this by calling it with commit=False. We can use commit=False in :meth:`~DjangoItem.save` method to obtain an unsaved model:

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>>> person = p.save(commit=False)
>>> person.name
'John'
>>> person.age
'22'
>>> person.id
None

As said before, we can add other fields to the item:

class PersonItem(DjangoItem):
    django_model = Person
    sex = Field()

p = PersonItem()
p['name'] = 'John'
p['age'] = '22'
p['sex'] = 'M'

Note

fields added to the item won't be taken into account when doing a :meth:`~DjangoItem.save`

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And we can override the fields of the model with your own:

class PersonItem(DjangoItem):
    django_model = Person
    name = Field(default='No Name')

This is usefull to provide properties to the field, like a default or any other property that your project uses.

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DjangoItem

Using DjangoItem

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