Question

注意：这并不是真正关于让Django的中间模型与多对多关系的额外字段工作。这是关于如何使用Django Rest Framework的Serializers.ModelSerializer与中间模型。我有这些模型（以及更多）：

class Method(models.Model):
    name = models.CharField(max_length=50, unique=True)
    descripton = models.TextField(null=False)

class Version(models.Model):
    version_number = models.CharField(max_length=50)
    cmd_line_script = models.CharField(max_length=250, null=False)
    SOP = models.TextField(null=False)
    FK_method = models.ForeignKey(Method, on_delete=models.CASCADE)

    class Meta:
        unique_together = ('version_number', 'FK_method')

class Instrument(models.Model):
    serial_number = models.CharField(max_length=50, unique=True)
    asset_number = models.CharField(max_length=50, unique=True)
    name = models.CharField(max_length=50)
    checksum_string = models.CharField(max_length=128, null=True)
    FK_instr_type = models.ForeignKey(InstrType, related_name='installations', on_delete=models.PROTECT)
    Instr_Version = models.ManyToManyField(
                        Version, 
                        through='Instr_Version', 
                        related_name = 'Instr_Version',
                    )

class Instr_Version(models.Model):
    FK_version = models.ForeignKey(Version, on_delete=models.CASCADE)
    FK_instrument = models.ForeignKey(Instrument, on_delete=models.CASCADE)
    validating_user = models.ForeignKey(UserProfile, on_delete=models.PROTECT)
    timestamp = models.DateField(auto_now_add=True)

    class Meta:
        unique_together = ('FK_version', 'FK_instrument')

他们很好。我正在尝试使用[Django-Rest-Framework serializers][1]来序列化Instr_Version表，以便api可以检索所有版本的json表示（以及它们的FK_method数据，通过MethodSerializer），这些表示列为对该工具有效。到目前为止，我有这些序列化程序（还有一些用于InstrType，UserProfile等）

class MethodSerializer(serializers.ModelSerializer):
    class Meta:
        model = Method
        fields = ('id', 'name', 'description', 'version_set')

class VersionSerializer(serializers.ModelSerializer):
    method = MethodSerializer(read_only=True)
    #Instr_Version = Instr_VersionSerializer(source='Instr_Version_set', many=True, read_only=True)
    class Meta:
        model = Version
        fields = ('id', 'method', 'version_number', 'cmd_line_script', 'SOP')

class Instr_to_VersionSerializer(serializers.ModelSerializer):
    version = VersionSerializer(source='FK_version_id', read_only=True, many=False)
    validator = UserProfileSerializer(source='validating_user', read_only=True)

    class Meta:
        model = Instr_Version
        fields = ('id', 'version', 'validator', 'timestamp')


class InstrumentSerializer(serializers.ModelSerializer):
    instr_type = InstrTypeSerializer(source='FK_instr_type', read_only=True)
    Validated_Versions = Instr_to_VersionSerializer(source='Instr_Version', many=True, read_only=True)

    class Meta:
        model = Instrument
        fields = ('id', 'asset_number', 'serial_number', 'name', 'checksum_string', 'instr_type', 'Validated_Versions')

我得到的最接近的是GET，如：“api / getInstrument /？asset_number = 1234” 结果：

{
    "id": 11,
    "asset_number": "1234",
    "serial_number": "1234",
    "name": "Instrument1",
    "checksum_string": "0123456789ABCDEF0123",
    "instr_type": {
        "id": 70,
        "make": "Make1",
        "model": "Model1",
        "service_email": "model1@company.com",
        "service_website": "www.model1.com"
    },
    "Validated_Versions": [{
        "id": 9
    }, {
        "id": 10
    }, {
        "id": 12
    }]
}

这是非常好的，但validated_versions数组应该有比'id'更多的数据。

为了实验，我尝试在id和Instr_to_VersionSerializer的字段列表中添加/删除VersionSerializer。证据表明id中字段列表中的Instr_to_VersionSerializer实际上是在FK_version_id模型上打印Instr_Version（或版本模型上的PK），而不是PK像我预期的那样Instr_Version。这让我觉得DJR“自动”通过多对多直接看到Version模型，所以我尝试将Instr_to_VersionSerializer更改为：

class Instr_to_VersionSerializer(serializers.ModelSerializer):
    #version = VersionSerializer(source='FK_version_id', read_only=True, many=False)
    validator = UserProfileSerializer(source='validating_user', read_only=True)
    #method = MethodSerializer(read_only=True)

    class Meta:
        model = Instr_Version
        fields = ('id', 'version_number', 'cmd_line_script', 'SOP', 'validator', 'timestamp')

哪个会让VersionSerializer完全退出，但我收到Field name版本号is not valid for model Instr_Version .错误，所以我不确定发生了什么。

我自己最后一次尝试是将source的{{1}}更改为version = VersionSerializer，这是相反的关系。这似乎不合逻辑，但我正处于那个我正在尝试任何事情的地步。结果是：versions不是有效字段的错误，它告诉我我终于到达了version_number，所以我在VersionSerializer中注释了大部分字段只是为了看看是什么正在发生，但这只会导致： VersionSerializer

Answer 1

related_name与Instruments之间的关系Instr_Version导致了问题。我将模型更新为：

class Instrument(models.Model):
    serial_number = models.CharField(max_length=50, unique=True)
    asset_number = models.CharField(max_length=50, unique=True)
    name = models.CharField(max_length=50)
    checksum_string = models.CharField(max_length=128, null=True)
    FK_instr_type = models.ForeignKey(InstrType, related_name='installations', on_delete=models.PROTECT)
    VersionsFromInstrument = models.ManyToManyField(
                        Version, 
                        through='Instr_Version', 
                        related_name = 'InstrumentsFromVersion',
                    )

（注意最后一个属性上的新相关名称，我更改了属性名称）和相应的序列化程序，这样做效果更好。请注意，在更新此模型后，我使用makemigrations运行了migrate和manage.py，然后它正在运行。新结果是：

{
    "id": 11,
    "asset_number": "1234",
    "serial_number": "1234",
    "name": "Instrument1",
    "checksum_string": "0123456789ABCDEF0123",
    "instr_type": {
        "id": 70,
        "make": "Make1",
        "model": "Model1",
        "service_email": "model1@company.com",
        "service_website": "www.model1.com"
    },
    "Validated_Versions": [{
        "id": 9,
        "method": {
            "id": 9,
            "name": "Method1",
            "description": "method one description",
            "version_set": [11, 9]
        },
        "version_name": "123",
        "cmd_line_script": "script",
        "SOP": "SOP"
    }, {
        "id": 10,
        "method": {
            "id": 10,
            "name": "Method2",
            "description": "method two description",
            "version_set": [12, 10]
        },
        "version_name": "123",
        "cmd_line_script": "script",
        "SOP": "SOP"
    }, {
        "id": 12,
        "method": {
            "id": 10,
            "name": "Method2",
            "description": "method two description",
            "version_set": [12, 10]
        },
        "version_name": "456",
        "cmd_line_script": "script",
        "SOP": "SOP"
    }]
}

如果它将来对其他人有帮助，请点击我更新的Serilaizers与模型的变化相关联：

class MethodSerializer(serializers.ModelSerializer):
    description = serializers.ReadOnlyField(source='descripton')
    class Meta:
        model = Method
        fields = ('id', 'name', 'description', 'version_set')

class VersionSerializer(serializers.ModelSerializer):
    method = MethodSerializer(read_only=True)
    #Instr_Version = Instr_VersionSerializer(source='Instr_Version_set', many=True, read_only=True)
    class Meta:
        model = Version
        fields = ('id', 'method')#, 'version_number', 'cmd_line_script', 'SOP')

class Instr_to_VersionSerializer(serializers.ModelSerializer):
    version = VersionSerializer(source='FK_version', read_only=True, many=True)
    validator = UserProfileSerializer(source='validating_user', read_only=True)
    version_name = serializers.ReadOnlyField(source='version_number')
    cmd_line_script = serializers.ReadOnlyField()
    SOP = serializers.ReadOnlyField()
    method = MethodSerializer(source='FK_method',read_only=True)

    class Meta:
        model = Instr_Version
        fields = ('id', 'version', 'validator', 'timestamp', 'method', 'version_name', 'cmd_line_script', 'SOP')


class InstrumentSerializer(serializers.ModelSerializer):
    instr_type = InstrTypeSerializer(source='FK_instr_type', read_only=True)
    Validated_Versions = Instr_to_VersionSerializer(source='VersionsFromInstrument', many=True, read_only=True)

    class Meta:
        model = Instrument
        fields = ('id', 'asset_number', 'serial_number', 'name', 'checksum_string', 'instr_type', 'Validated_Versions')

特别注意Validated_Versions =

的InstrumentSerializer行

我遗漏的一件事是，我真的希望在结果中看到validating_user模型上的timestamp和Instr_Version字段，所以我仍然需要继续那。当我开始工作时，我会更新。

具有多对多模型的django drf序列化程序（带有额外数据）

1 个答案: