Question

我在序列化模型对象的Flask应用程序中遇到一个问题，该问题与关联表中存储的额外字段有多对多的关系。我想要一个序列化的数据，如下所示：

{
    "id": "123",
    "name": "name",
    "mobile": "phone number",
    "interest": [1, 2, 3]
    "_embedded": {
        "interest": [
            {
                "id": 1,
                "name": "ECONOMIC",
                "active": true,
            },
            {
                "id": 2,
                "name": "POETRY",
                "active": true,
            },
            {
                "id": 3,
                "name": "SPORT",
                "active": false,
            },
        ]
    }
}

现在，我设法准备了必要的模型，如下所示：

class OwnerInterests(db.Model):
    owner_id = db.Column(db.Integer, db.ForeignKey('owners.id'), primary_key=True)
    interest_id = db.Column(db.Integer, db.ForeignKey('interests.id'), primary_key=True)
    active = db.Column(db.Boolean)
    interest = db.relationship('Interests', back_populates='owners')
    owner = db.relationship('Owners', back_populates='interests')


class Owners(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    mobile = db.Column(db.String)
    interests = db.relationship('OwnersInterests', back_populates='owner')


class Interests(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    owners = db.relationship('OwnersInterests', back_populates='interest')

但是现在我想知道方法，如何使用棉花糖模式准备sqlalchemy查询。有什么想法吗？

编辑：

我当前的棉花糖模式如下：

class InterestSchema(ma.ModelSchema):
    class Meta:
        model = Interests
        exclude = ('owners',)


class OwnerSchema(ma.ModelSchema):
    interests = ma.Nested(InterestSchema, many=True)

    class Meta:
        model = Owners

Answer 1

此架构为您提供了与您的规范非常相似的内容：

from marshmallow import Schema, fields


class InterestSchema(Schema):
    class Meta:
        fields = ('id', 'name')
        ordered = True


class OwnerInterestSchema(Schema):
    interest = fields.Nested(InterestSchema)

    class Meta:
        fields = ('id', 'interest', 'active')
        ordered = True


class OwnerSchema(Schema):
    interests = fields.Nested(OwnerInterestSchema, many=True)

    class Meta:
        fields = ('id', 'name', 'mobile', 'interests')
        ordered = True

然后您可以像这样序列化数据（请注意，我的模型名称与您的模型不完全相同）：

>>> from app.serialisation import OwnerSchema
>>> from app.models import Owner
>>> data = OwnerSchema().dump(Owner.query.get(1))
>>> from marshmallow import pprint
>>> pprint(data)
{"id": 1, "name": "John", "mobile": "07123456789", "interests": [{"interest": {"id": 1, "name": "Economics"}, "active": true}, {"interest": {"id": 2, "name": "Poetry"}, "active": true}, {"interest": {"id": 3, "name": "Sport"}, "active": false}]}

让我只是缩进输出内容，以便您查看发生了什么事情

{
  "id": 1,
  "name": "John",
  "mobile": "07123456789",
  "interests": [
    {
      "interest": {
        "id": 1,
        "name": "Economics"
      },
      "active": true
    },
    {
      "interest": {
        "id": 2,
        "name": "Poetry"
      },
      "active": true
    },
    {
      "interest": {
        "id": 3,
        "name": "Sport"
      },
      "active": false
    }
  ]
}

您可以根据需要对此进行调整，以使用“模型加排除”范例。而且，如果您确实想要JSON中的"_embedded"字段，则可能需要一个自定义字段，如here所述。

您还可以使用自定义字段来平息您的兴趣，并将"active"字段与"id"和"name"放在同一级别，但是我认为这会产生误导。

烧瓶棉花糖与额外字段序列化多对多关系

1 个答案: