68 lines
1.9 KiB
Python
68 lines
1.9 KiB
Python
from __future__ import unicode_literals
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class BaseInstanceLoader(object):
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"""
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Base abstract implementation of instance loader.
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"""
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def __init__(self, resource, dataset=None):
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self.resource = resource
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self.dataset = dataset
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def get_instance(self, row):
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raise NotImplementedError
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class ModelInstanceLoader(BaseInstanceLoader):
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"""
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Instance loader for Django model.
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Lookup for model instance by ``import_id_fields``.
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"""
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def get_queryset(self):
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return self.resource._meta.model.objects.all()
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def get_instance(self, row):
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try:
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params = {}
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for key in self.resource.get_import_id_fields():
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field = self.resource.fields[key]
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params[field.attribute] = field.clean(row)
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if params:
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return self.get_queryset().get(**params)
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else:
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return None
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except self.resource._meta.model.DoesNotExist:
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return None
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class CachedInstanceLoader(ModelInstanceLoader):
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"""
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Loads all possible model instances in dataset avoid hitting database for
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every ``get_instance`` call.
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This instance loader work only when there is one ``import_id_fields``
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field.
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"""
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def __init__(self, *args, **kwargs):
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super(CachedInstanceLoader, self).__init__(*args, **kwargs)
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pk_field_name = self.resource.get_import_id_fields()[0]
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self.pk_field = self.resource.fields[pk_field_name]
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ids = [self.pk_field.clean(row) for row in self.dataset.dict]
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qs = self.get_queryset().filter(**{
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"%s__in" % self.pk_field.attribute: ids
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})
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self.all_instances = {
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self.pk_field.get_value(instance): instance
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for instance in qs
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}
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def get_instance(self, row):
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return self.all_instances.get(self.pk_field.clean(row))
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