问题描述

我在 SO 上看到了一些与此类似的问题，但似乎没有一个能回答我的特定问题.我是 Django 新手，并按照 此页面上的说明指导自己 允许自己使用自然键来加载固定装置.不过，我收到了反序列化错误，因为 Django 想要一个整数作为外键，并且似乎无法将我的自然键映射到说明中所述的整数主键.具体来说，我的相关模型代码是:

I've seen a few similar questions to this on SO, but none seem to answer my particular problem. I'm new to Django and was guiding myself by the instructions at this page to allow myself to use natural keys to load fixtures. Nevertheless, I'm getting Deserialization errors because Django wants an integer for a foreign key and can't seem to map my natural key to an integer primary key as is noted in the instructions. Specifically, my relevant models code is:

class GraphTypeManager(models.Manager):
    def get_by_natural_key(self, type):
        return self.get(type=type)
class GraphType(models.Model):
    type = models.CharField(max_length=100, unique=True)

class GraphManager(models.Manager):
    def get_by_natural_key(self, name):
        return self.get(name=name)
class Graph(models.Model):
    name = models.CharField(max_length=200, unique=True)
    type = models.ForeignKey(GraphType)

class LineManager(models.Manager):
    def get_by_natural_key(self, name):
        return self.get(name=name)
class Line(models.Model):
    name = models.CharField(max_length=200, unique=True)

class GraphToLineManager(models.Manager):
    def get_by_natural_key(self, line, graph):
        return self.get(line=line,graph=graph)
class GraphToLine(models.Model):
    line = models.ForeignKey(Line)
    graph = models.ForeignKey(Graph)
    class Meta:
        unique_together = (('line', "graph"),)

我的 YAML 夹具是:

And my YAML fixture is:

- model: graphs_container.GraphType
  pk: null
  fields:
    type: TimeSeries
- model: graphs_container.Graph
  pk: null
  fields:
    name: LikesOverTime
    type: [TimeSeries]
- model: graphs_container.Graph
  pk: null
  fields:
    name: UsersOverTime
    type: [TimeSeries]
- model: graphs_container.Line
  pk: null
  fields:
    name: NumUsers
- model: graphs_container.Line
  pk: null
  fields:
    name: NumLikes

但是在尝试运行 python manage.py loaddata sample_data.yaml 时，我收到以下错误:

But when trying to run python manage.py loaddata sample_data.yaml, I get the following error:

DeserializationError: [u"'['TimeSeries']' value must be an integer."]

我做错了什么?

推荐答案

你需要

• 在模型中定义 natural_key 方法
• 拥有一个具有 get_by_natural_key 方法的经理
• 实际附加管理器(objects=GraphManager())

• define natural_key method in your models
• have a manager with get_by_natural_key method
• actually attach the managers (objects=GraphManager())

在玩过你的代码之后，我让它工作了:

After playing with your code, I made it work:

class GraphTypeManager(models.Manager):
    def get_by_natural_key(self, type):
        return self.get(type=type)

class GraphType(models.Model):
    type = models.CharField(max_length=100, unique=True)
    objects = GraphTypeManager()

    def natural_key(self):
        return (self.type,)  # must return a tuple

class GraphManager(models.Manager):
    def get_by_natural_key(self, name):
        return self.get(name=name)

class Graph(models.Model):
    name = models.CharField(max_length=200, unique=True)
    type = models.ForeignKey(GraphType)
    objects = GraphManager()

转储数据:

$ bin/django dumpdata index --indent=4 --natural > project/apps/fixtures_dev/initial_data.json
[
    {
        "pk": 1,
        "model": "index.graphtype",
        "fields": {
            "type": "asotuh"
        }
    },
    {
        "pk": 1,
        "model": "index.graph",
        "fields": {
            "type": [
                "asotuh"
            ],
            "name": "saoneuht"
        }
    }
]

bin/django loaddata project/apps/fixtures_dev/initial_data.json 
Installed 2 object(s) from 1 fixture(s)