Question

我正在用scrapy做一个废料，我在django上的模型是：

class Creative(models.Model):
    name = models.CharField(max_length=200)
    picture = models.CharField(max_length=200, null = True)

class Project(models.Model):
    title = models.CharField(max_length=200)
    description = models.CharField(max_length=500, null = True)
    creative = models.ForeignKey(Creative)

class Image(models.Model):
    url = models.CharField(max_length=500)
    project = models.ForeignKey(Project)

我的scrapy模型：

from scrapy.contrib.djangoitem import DjangoItem
from app.models import Project, Creative

class ProjectItems(DjangoItem):
    django_model = Project

class CreativeItems(DjangoItem):
    django_model = Creative

所以当我保存时：

creative["name"]  = hxs.select('//*[@id="owner"]/text()').extract()[0]
picture  = hxs.select('//*[@id="owner-icon"]/a/img/@src').extract()
if len(picture)>0:
    creative["picture"] = picture[0]
creative.save()


# Extract title and description of the project
project["title"] = hxs.select('//*[@id="project-title"]/text()').extract()[0]
description = hxs.select('//*[@class="project-description"]/text()').extract()
if len(description)>0:
    project["description"] = description[0]
project["creative"] = creative
project.save()

我收到了错误：

Project.creative“必须是”Creative“实例。

那么，我怎样才能在scrapy上添加一个foreing key值？

Answer 1

这可以通过将creative.save()的返回值分配给project['creative']处的值来完成。例如，在以下示例中，我们使用djangoCreativeItem变量将此信息传递给项目：

creative["name"]  = hxs.select('//*[@id="owner"]/text()').extract()[0]
picture  = hxs.select('//*[@id="owner-icon"]/a/img/@src').extract()   
if len(picture)>0:
    creative["picture"] = picture[0]
djangoCreativeItem = creative.save()

# Extract title and description of the project
project["title"] = hxs.select('//*[@id="project-title"]/text()').extract()[0]
description = hxs.select('//*[@class="project-description"]/text()').extract()
if len(description)>0:
    project["description"] = description[0]
project["creative"] = djangoCreativeItem
project.save()

Answer 2

与it's been done here一样，将广告素材的ID直接放在creative_id中，我认为它应该有效：

 project["creative_id"] = creative.id

它将指定外键，而不会因缺少对象而烦恼（因为您处于不直接触摸模型对象的Scrapy环境中......）。

Scrapy上的外键

2 个答案: