3

我正在使用 django 导入导出库来处理数据。它工作得很好，除了我不能让它导入外键中不存在的对象。

如果外键模型中存在对象（csv 中的值），那么它可以正常导入。

但是如果外键模型中不存在对象/值 - 它会说“匹配查询不存在”并且不会导入数据。

如果外键中不存在新对象，我如何告诉它将新对象添加到外键模型中？

Models.py 片段

class Store(models.Model):

    store_name = models.CharField(max_length=30)
    def __unicode__(self):
        return self.store_name
    #etc

class Product(models.Model):

    Store = models.ForeignKey(Store)
    Category = models.ForeignKey(Category)
    first_name = models.CharField(max_length=30)
    second_name = models.CharField(max_length=30)
...

Admin.py 片段

admin.site.register(Category)
admin.site.register(Store)

class ProductResource(resources.ModelResource):

     store_name = fields.Field(column_name='store_name', attribute='Store',
                       widget=ForeignKeyWidget(Store, 'store_name'))

    def __unicode__(self):
        return self.store_name.name

    class Meta:
        model = Product
        fields = ('id', 'first_name', 'second_name','store_name')
        export_order = ('id', 'second_name', 'first_name')
        skip_unchanged = False
        report_skipped = False
        widgets = {
                'published': {'format': '%d.%m.%Y'},
                }


class ProductAdmin(ImportExportModelAdmin):
    resource_class = ProductResource
    list_display = ('first_name', 'second_name')

admin.site.register(Product, ProductAdmin)
4

4 回答 4

2

在ForeignKeyWidget你有方法

  def clean(self, value):
        val = super(ForeignKeyWidget, self).clean(value)
        return self.model.objects.get(**{self.field: val}) if val else None

您可以尝试覆盖它以执行类似get_or_create...

它应该看起来像这样......

from import_export.widgets import ForeignKeyWidget
class MyCustomizationToFKWidget(ForeignKeyWidget):

      def clean(self, value):
            val = super(ForeignKeyWidget, self).clean(value)
            HERE SOME LOGIC OVERRIDEN
于 2015-09-03T08:08:22.117 回答
2

如果您的模型的 ForeignKey 可以为 null ：

MyForeignKeyName = Models.ForeignKey(<modelclass>,blank=True, null=True)

您可以在 Resource 类中添加before_import_row()方法：

def before_import_row(self,row) :
    fieldname = 'MyForeignKeyName'
    if not( <modelclass>.objects.filter(pk=row[fieldname]).exists() ) :
        # print(row['id'],row[fieldname],'unknown key !') # console log
        row[fieldname ] = None # or something else.. *

*.. 符合您的外键配置[python None = SQL null]

我对 Django 有点陌生，所以也许这不是更好的方法，但这解决了我的问题。

还有一些关于 db_constraint=False 的内容可以添加到 ForeignKey 的参数（一些信息@stackoverflow和@django），但是，我没有找到我的方法。

于 2017-07-03T22:57:03.553 回答
1

您可以在Resource 类的before_import_row()方法中创建缺少的外键条目：

class ProductResource(resources.ModelResource):
    ...
    def before_import_row(self, row, **kwargs):
        Store.objects.get_or_create(
            store_name=row.get('store_name')
        )
于 2020-03-25T13:52:38.840 回答
0

我发现最好的方法是使用自定义小部件。我在这里的 django-import-export GitHub 项目上找到了一个线程，其中包含很多有用的信息。由此我将这两个支持创建新对象的自定义小部件拼凑在一起。admin.py通过将它们添加到您的模块中，它们都应该按原样工作：

from import_export.widgets import ManyToManyWidget
from django.db.models import QuerySet


class ForeignKeyWidgetWithCreation(ForeignKeyWidget):
    """
    Taken from a GitHub post.
    https://github.com/django-import-export/django-import-export/issues/318#issuecomment-139989178
    """

    def __init__(self, model, field="pk", create=False, **kwargs):
        self.model = model
        self.field = field
        self.create = create
        super(ForeignKeyWidgetWithCreation, self).__init__(model, field=field, **kwargs)

    def clean(self, value, **kwargs):
        if not value:
            return None

        if self.create:
            self.model.objects.get_or_create(**{self.field: value})

        val = super(ForeignKeyWidgetWithCreation, self).clean(value, **kwargs)

        return self.model.objects.get(**{self.field: val}) if val else None


class ManyToManyWidgetWithCreation(ManyToManyWidget):
    """
    Taken from a GitHub post.
    https://github.com/django-import-export/django-import-export/issues/318#issuecomment-139989178
    """

    def __init__(self, model, field="pk", create=False, **kwargs):
        self.model = model
        self.field = field
        self.create = create
        super(ManyToManyWidgetWithCreation, self).__init__(model, field=field, **kwargs)

    def clean(self, value, **kwargs):

        # If no value was passed then we don't have anything to clean.

        if not value:
            return self.model.objects.none()

        # Call the super method. This will return a QuerySet containing any pre-existing objects.
        # Any missing objects will be

        cleaned_value: QuerySet = super(ManyToManyWidgetWithCreation, self).clean(
            value, **kwargs
        )

        # Value will be a string that is separated by `self.separator`.
        # Each entry in the list will be a reference to an object. If the object exists it will
        # appear in the cleaned_value results. If the number of objects in the cleaned_value
        # results matches the number of objects in the delimited list then all objects already
        # exist and we can just return those results.

        object_list = value.split(self.separator)

        if len(cleaned_value.all()) == len(object_list):
            return cleaned_value

        # If we are creating new objects then loop over each object in the list and
        # use get_or_create to, um, get or create the object.

        if self.create:
            for object_value in object_list:
                _instance, _new = self.model.objects.get_or_create(
                    **{self.field: object_value}
                )

        # Use `filter` to re-locate all the objects in the list.

        model_objects = self.model.objects.filter(**{f"{self.field}__in": object_list})

        return model_objects

您可以在您的导入导出模型资源类中使用它们，如下所示：

class SomeModelResource(Resource):
    my_fk_field = fields.Field(
        attribute='my_fk_field',
        widget=ForeignKeyWidgetWithCreation(
            model=models.OtherModel,
            field='name',
            create=True))

    my_m2m_field = fields.Field(
        attribute="my_m2m_field",
        widget=ManyToManyWidgetWithCreation(
            model=models.OtherM2MModel,
            field="name",
            separator="|",
            create=True,
        ),
        default="",
    )
于 2021-06-16T15:20:17.603 回答