django-import-export关联外键在后台管理中导入导出的办法

程序员文章站 2022-03-08 22:38:46

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本文介绍django-import-export在关联外键时，导出可以导出可读字样（而非关联id），导入通过可读字眼进行导入（而非关联id）

模型设计如下：


# models.py
from django.db import models

# Create your models here.


class User(models.Model):
    gender_by_choice = (
        ('male', '男'),
        ('female', '女'),
    )

    username = models.CharField(max_length=10, unique=True, verbose_name='姓名')
    age = models.IntegerField(verbose_name='年龄')
    gender = models.CharField(max_length=6, choices=gender_by_choice, verbose_name='性别')
    nickname = models.CharField(max_length=10, verbose_name='昵称')

    def __str__(self):
        return self.username

    class Meta:
        verbose_name = '用户'
        verbose_name_plural = '用户'


class Book(models.Model):
    owner = models.ForeignKey(User, null=True, blank=True, on_delete=models.SET_NULL, verbose_name='归属者')
    name = models.CharField(max_length=64, verbose_name='书名')

    def __str__(self):
        return self.name

    class Meta:
        verbose_name = '书'
        verbose_name_plural = '书'

可以看到上述的Book模型中的owner关联了User表，先按照django-import-export的官网所述的方法配置，看看会遇到什么问题

配置admin.py


# admin.py
from import_export import resources
from import_export.admin import ImportExportModelAdmin

class BookResource(resources.ModelResource):
    class Meta:
        model = Book


class BookAdmin(ImportExportModelAdmin):
    resource_class = BookResource
    # 这里加几个显示字段
    list_display = ['name', 'owner']


class UserResource(resources.ModelResource):
    class Meta:
        model = User


class UserAdmin(ImportExportModelAdmin):
    resource_class = UserResource
    # 这里加几个显示字段
    list_display = ['username', 'age', 'gender', 'nickname']


admin.site.register(Book, BookAdmin)
admin.site.register(User, UserAdmin)

如下图，右上角已经有了导入导出按钮，django-import-export已经加载成功

录入两条用户数据和三条书籍信息，如下图：

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如果将书籍导出，会得到如下效果，owner会显示user表的id信息，并不是我们想要的结果：
django-import-export关联外键在后台管理中导入导出的办法

导入会有同样的问题，导入时owner中的值必须是user中的id，而不能是张三、李四，所以我们需要对导入和导出做一些调整，以实现我们的需求：


from django.contrib import admin
from .models import Book, User
from import_export import resources
from django.apps import apps
from import_export.admin import ImportExportModelAdmin
from django.db import models
import tablib
import collections

class BookResource(resources.ModelResource):
    def __init__(self):
        super(BookResource, self).__init__()
        # 获取tables应用下Book模型中的所有字段，请根据自己的应用将tables更改
        field_list = apps.get_model('tables', 'Book')._meta.fields
        self.vname_dict = {}
        self.fkey = []
        for i in field_list:
            self.vname_dict[i.name] = i.verbose_name    # 获取所有字段的verbose_name并存放在字典
            if(isinstance(i, models.ForeignKey)):
                self.fkey.append(i.name)    # 获取所有ForeignKey字段的name存放在列表

    def export(self, queryset=None, *args, **kwargs):
        self.before_export(queryset, *args, **kwargs)

        if queryset is None:
            queryset = self.get_queryset()

        headers = self.get_export_headers()
        data = tablib.Dataset(headers=headers)

        # 获取所有外键名称在headers中的位置
        fk_index = {}
        for fk in self.fkey:
            fk_index[fk] = headers.index(fk)

        iterable = queryset
        for obj in iterable:
            # 获取将要导出的源数据，这里export_resource返回的是列表，便于更改。替换到外键的值
            res = self.export_resource(obj)
            """
            这里是关键，将owner的值到User中获取对应的对象，并截取起可读名称username，
            这里用的是get，所以在User的模型中username必须是unique
            """
            res[fk_index['owner']] = User.objects.get(id=res[fk_index['owner']]).username
            data.append(res)
        self.after_export(queryset, data, *args, **kwargs)
        return data

    def before_import(self, dataset, using_transactions, dry_run, **kwargs):
        dict = []
        for row in dataset.dict:
            tmp = collections.OrderedDict()
            books = Book.objects.all()
            for item in row:
                if item == 'owner':
                    """
                    这里是关键，通过可读名称到User表中找到对应id，并加到导入的数据中去
                    """
                    tmp[item] = User.objects.get(username=row[item]).id
                else:
                    tmp[item] = row[item]
            """
            这里是关键，将数据进行比对，如果数据相同，就把原先在Book表中的id加到需要导入的数据中去，
            这样就不会新增和原先一模一样的数据，类似于create_or_update方法
            """
            for book in books:
                if row['name'] == book.name:
                    tmp['id'] = book.id
            dict.append(tmp)
        dataset.dict = dict
        return dataset

    class Meta:
        model = Book


class BookAdmin(ImportExportModelAdmin):
    resource_class = BookResource


class BookAdmin(ImportExportModelAdmin):
    resource_class = BookResource
    list_display = ['name', 'owner']


class UserResource(resources.ModelResource):
    class Meta:
        model = User


class UserAdmin(ImportExportModelAdmin):
    resource_class = UserResource
    list_display = ['username', 'age', 'gender', 'nickname']


admin.site.register(Book, BookAdmin)
admin.site.register(User, UserAdmin)