Django与现有对象的多对一关系 [英] Many to One Relation in Django With Existing Objects

问题描述

我昨天开始学习Django，但在基于先前创建的对象创建一对多关系时遇到了一些麻烦.

I've started to study Django yesterday and I'm having some trouble with to creating a Many to One Relation based on objects I've previously created.

# -*- coding: utf-8 -*-
from django.db import models

class Item(models.Model):
    code = models.AutoField(primary_key=True)
    name = models.CharField(max_length=150, unique=True)

    class Meta:
        ordering = ('name', 'code')

    def __unicode__(self):
        return self.name


class Product(models.Model):
    code =  models.AutoField(primary_key=True)
    name = models.CharField(max_length=150, unique=True)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    photo = models.ImageField(null=True, blank=True, upload_to='/img/products')
    items = models.ForeignKey('Item')

    class Meta:
        ordering = ('name', 'code')

    def __unicode__(self):
        return self.name

admin.py

# -*- coding: utf-8 -*-
from django.contrib import admin
from Cadastro.models import Item, Product

class ItemAdmin(admin.ModelAdmin):
    model = Item
    list_display = ['code', 'name']
    list_filter = []
    search_fields = ['name', 'code']
    save_on_top = True


class ProductAdmin(admin.ModelAdmin):
    model = Product
    list_display = ['name', 'price']
    list_filter = []
    search_fields = ['name']
    save_on_top = True

admin.site.register(Item, ItemAdmin)
admin.site.register(Product, ProductAdmin)

问题:

我的问题在这里:

Problem:

My problem is here:

items = models.ForeignKey('Item')

首先，我想创建各种 Item 对象.

I want to create various Item objects, first.

此后，当我创建产品时，我想查看所有项目的列表，并选择许多项目作为的一部分产品.

After that, when I'll create the Products, I want to see a list of all my Items and select many items to be part of a Product.

推荐答案

您的关系正走错路.如果Product可以具有多个Item，则将ForeignKey从Item更改为Product.在Product上使用ForeignKey时，您要说的是每个产品只有一个Item，但是每个Item可以属于多个Product.

Your relationship is going the wrong way. If a Product can have multiple Items, make a ForeignKey from Item to Product. With the ForeignKey on Product, you're saying each product has exactly one Item, but each Item can belong to multiple Products.

文档具有更多详细信息和示例: https://docs.djangoproject.com/en/1.7/topics/db/examples/many_to_one/

The docs have more details and examples: https://docs.djangoproject.com/en/1.7/topics/db/examples/many_to_one/

这篇关于Django与现有对象的多对一关系的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！