rest - Flask restful，Marshmellow，SqlAlchemy，带有嵌套资源的 POST 请求

Question

我有一个如下所示的嵌套数据库模型、一个相应的 Marshmellow Schema 和一个 Flask Restful 资源。

如何使用 POST 请求将嵌套的 Contract（以及嵌套的 ContractComponent 等）对象添加到数据库中？

# Sql Alchemy Model(s)
Customer
 - name, address ... 
 - contracts
    Contract
     - Contract Components
        - MonthlyRecurringCharges
           - ..

# Marshmellow Schema
class CustomerSchema(ma.Schema):
class Meta:
    fields = ("id", "name", "grouptag", "country",
              "segment", "status", "contracts", "created_on")
    model = Customer
contracts = ma.Nested(ContractSchema, many=True)

# Flask Restful Resource extract
    CustomerListResource(Resource)
        if Customer.find_by_name(request.json['name']) == None:
            c_name = request.json["name"]
            c_contracts = request.json.get("contracts", None)
            c_grouptag = request.json.get("grouptag", None)
            c_segment = request.json.get("segment", None)
            c_status = request.json.get("status", None)
            c_country = request.json.get("country", None)
            new_customer = Customer(
                name=c_name,
                contracts=c_contracts,
                grouptag=c_grouptag,
                segment=c_segment,
                status=c_status,
                country=c_country
            )
            db.session.add(new_customer)
            db.session.commit()
            return customer_schema.dump(new_customer)

如果我发送以下请求，我会收到一个 AttributeError

AttributeError：“dict”对象没有属性“_sa_instance_state”

{
    "name": "xyz",
    "segment": "Grocery",
    "id": 1,
    "status": "Active",
    "created_on": "2022-01-24T07:36:33",
    "grouptag": null,
    "contracts": [
        {
            "created_on": "2022-01-24T07:36:33.768153",
            "customer_id": 1,
            "id": 1,
            "components": [...] 
        },
}