固定装置的 Django 自然键给出反序列化错误

Question

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this page 的说明指导自己，以允许自己使用自然键来加载固定装置。尽管如此，我得到了反序列化错误，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：

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：

- 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

但在尝试运行python manage.py loaddata sample_data.yaml 时，出现以下错误：

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

我做错了什么？

Answer 1

你需要

• 在模型中定义 natural_key 方法
• 有一个具有get_by_natural_key 方法的经理
• 实际附上管理员(objects=GraphManager())

在玩过你的代码之后，我让它工作了：

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)