Django REST 框架：连接表答案

【问题标题】：Django REST framework: Join tablesDjango REST 框架：连接表
【发布时间】：2022-01-21 02:22:06
【问题描述】：

我正在尝试创建一个 API 视图，用户在其中输入控制器的名称并接收它可以作为 JSON 返回的测量值。

models.py

class Microcontrollers(models.Model):
    name = models.CharField(max_length=25)
    serial_number = models.CharField(max_length=20, blank=True, null=True)
    type = models.CharField(max_length=15, blank=True, null=True)
    software = models.CharField(max_length=20, blank=True, null=True)
    version = models.CharField(max_length=5, blank=True, null=True)
    date_installed = models.DateField(blank=True, null=True)
    date_battery_last_replaced = models.DateField(blank=True, null=True)
    source = models.CharField(max_length=10, blank=True, null=True)
    friendly_name = models.CharField(max_length=45, blank=True, null=True)

class MicrocontrollersMeasurements(models.Model):
    microcontroller = models.ForeignKey(Microcontrollers, models.DO_NOTHING, blank=True, null=True)
    measurement = models.ForeignKey(Measurements, models.DO_NOTHING, blank=True, null=True)

class Measurements(models.Model):
    code = models.CharField(max_length=25)
    measurement = models.CharField(max_length=25)
    unit = models.CharField(max_length=25)
    type = models.CharField(max_length=25)

序列化器.py

class SourceStationsSerializer(serializers.ModelSerializer):

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

    class Meta:
        model = Microcontrollers
        fields = ['id', 'name']

class StationMeasurementsSerializer(serializers.ModelSerializer):
    
    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

    class Meta:
        model = MicrocontrollersMeasurements
        fields = '__all__'

class MeasurementsSerializer(serializers.ModelSerializer):
    station = SourceStationsSerializer()
    stationMeasurements = StationMeasurementsSerializer()

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

    class Meta:
        model = Measurements
        fields = '__all__'

数据库为每个控制器和测量创建 ID。我的问题是如何加入这 3 个表，以便找到属于每个控制器的测量值。

【问题讨论】：

标签： django django-models django-rest-framework django-views django-serializer

【解决方案1】：

你实际上并不需要 django 中的中间模型..

class Measurements(models.Model):
    microcontroller = models.ForeignKey(Microcontrollers,related_name="measurements",on_delete=models.DO_NOTHING, blank=True, null=True)
    code = models.CharField(max_length=25)
    measurement = models.CharField(max_length=25)
    unit = models.CharField(max_length=25)
    type = models.CharField(max_length=25)

注意related_name='measurements" 现在说，

pic = Microcontrollers.objects.get(id=1) #or any instance of MMicrocontrollers()
measurements_pic = pic.measurements.all() # will get a list of all measurements associated with pic

pic.measurements.all() 中的这个“测量值”是相关名称。 Django 创建了中间表和所有这些东西......并对其进行了简化。

用于输出目的

out = MeasurementsSerializer(measurements_pic,many=True)

将完成这项工作。注意：'type'是python中的关键字

【讨论】：