Django创建关联对象的字典

Question

我正在尝试构建一个查询，它将返回所有技术的列表以及与每个技术相关联的每个用户的得分。这基于以下模型：

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的东西：

{技术：思科，用户：{亚历克斯：{技能水平：1}}，{詹姆斯：{技能水平：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联接？你知道吗

我也不确定是应该在Technology模型还是Result模型上构建它？你知道吗

Answer 1

可能与此类似（请参见下面的测试.py文件）：

你知道吗型号.py地址：

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)

你知道吗测试.py地址：

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()的源
• How do I convert a Django QuerySet into list of dicts?