Django - 创建关联对象的字典

Question

我正在尝试构建一个查询，该查询将返回所有技术的列表以及与每种技术相关的每个用户的分数。这是基于以下模型：

class Technology(models.Model):
    technology = models.CharField(max_length=64)

class Result(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    technology = models.ForeignKey(technology, on_delete=models.CASCADE)
    skill_level = models.ForeignKey(skill, to_field='level', on_delete=models.CASCADE)

class Skill(models.Model):
    level = models.IntegerField(unique=True)

基本上我希望看​​到类似于以下内容：

{技术：思科，用户：{Alex: {skill_level: 1}}，{James: {skill_level: 2}}

我不确定这是否可以通过简单的查询来实现，或者是否需要进行自定义连接？

我也不确定是否应该在 Technology 模型或 Result 模型上构建它？

Answer 1

可能与此类似（请参阅 tests.py 文件的底部）：

models.py：

from django.db import models

class User(models.Model):
    name = models.CharField(max_length=64)

class Technology(models.Model):
    technology = models.CharField(max_length=64)

class Skill(models.Model):
    level = models.IntegerField(unique=True)

class Result(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    technology = models.ForeignKey(Technology, on_delete=models.CASCADE)
    skill_level = models.ForeignKey(Skill, to_field='level', on_delete=models.CASCADE)

tests.py：

from django.test import TestCase
from .models import Result, Technology, User, Skill
from django.forms.models import model_to_dict

class SimpleTest(TestCase):
    def test_join(self):
        u = []
        s = []
        for x in range(0,2):
            _u = User(name='User{}'.format(str(x)))
            _s = Skill(level=x)
            _u.save()
            _s.save()
            u.append(_u)
            s.append(_s)
        t = []
        for x in range(0, 4):
            _t = Technology(technology='blah{}'.format(str(x)))
            _t.save()
            t.append(_t)
        for x in range(0, 8):
            r = Result(user=u[x%2], technology=t[x%4], skill_level=s[x%2])
            r.save()

        x = Technology.objects.select_related()
        print(x.query)
        for item in x:
            print(item.result_set.values())
            print(item.result_set.all().query)
            for ok in item.result_set.all():
                print(model_to_dict(ok))

测试输出：

➜  mysite python manage.py test
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
SELECT "mysite_technology"."id", "mysite_technology"."technology" FROM "mysite_technology"
<QuerySet [{'id': 1, 'user_id': 1, 'technology_id': 1, 'skill_level_id': 0}, {'id': 5, 'user_id': 1, 'technology_id': 1, 'skill_level_id': 0}]>
SELECT "mysite_result"."id", "mysite_result"."user_id", "mysite_result"."technology_id", "mysite_result"."skill_level_id" FROM "mysite_result" WHERE "mysite_result"."technology_id" = 1
{'id': 1, 'user': 1, 'technology': 1, 'skill_level': 0}
{'id': 5, 'user': 1, 'technology': 1, 'skill_level': 0}
<QuerySet [{'id': 2, 'user_id': 2, 'technology_id': 2, 'skill_level_id': 1}, {'id': 6, 'user_id': 2, 'technology_id': 2, 'skill_level_id': 1}]>
SELECT "mysite_result"."id", "mysite_result"."user_id", "mysite_result"."technology_id", "mysite_result"."skill_level_id" FROM "mysite_result" WHERE "mysite_result"."technology_id" = 2
{'id': 2, 'user': 2, 'technology': 2, 'skill_level': 1}
{'id': 6, 'user': 2, 'technology': 2, 'skill_level': 1}
<QuerySet [{'id': 3, 'user_id': 1, 'technology_id': 3, 'skill_level_id': 0}, {'id': 7, 'user_id': 1, 'technology_id': 3, 'skill_level_id': 0}]>
SELECT "mysite_result"."id", "mysite_result"."user_id", "mysite_result"."technology_id", "mysite_result"."skill_level_id" FROM "mysite_result" WHERE "mysite_result"."technology_id" = 3
{'id': 3, 'user': 1, 'technology': 3, 'skill_level': 0}
{'id': 7, 'user': 1, 'technology': 3, 'skill_level': 0}
<QuerySet [{'id': 4, 'user_id': 2, 'technology_id': 4, 'skill_level_id': 1}, {'id': 8, 'user_id': 2, 'technology_id': 4, 'skill_level_id': 1}]>
SELECT "mysite_result"."id", "mysite_result"."user_id", "mysite_result"."technology_id", "mysite_result"."skill_level_id" FROM "mysite_result" WHERE "mysite_result"."technology_id" = 4
{'id': 4, 'user': 2, 'technology': 4, 'skill_level': 1}
{'id': 8, 'user': 2, 'technology': 4, 'skill_level': 1}
.
----------------------------------------------------------------------
Ran 1 test in 0.011s

OK
Destroying test database for alias 'default'...

相关：

• model_to_dict()的来源
• How do I convert a Django QuerySet into list of dicts?