flask-marshmallow 去掉小数点

Question

我正在使用 flask-marshmallow 和 flask-sqlalchemy，我想序列化一个包含数字字段的数据集，所有值都有小数位，即 2.5，但是当 marshmallow 将其转储到 json它切断了小数位（将 2.5 更改为 2）我哪里出错了？

ma.py

from flask_marshmallow import Marshmallow

ma = Marshmallow()

app.py

import ma
import db
from flask_restful import Api
.....
api = Api(app)

api.add_resource(LookupActivities, '/lookup_activity_by_type/<string:activity_type>')

if __name__ == "__main__":
    db.init_app(app)
    ma.init_app(app)
    app.run(port=5000, debug=True)

model/lookup.py

from db import db

class LookupModel(db.Model):
    __tablename__ = "asmirt_cpd_point_lookup"
    __table_args__ = {"schema": "radcpd"}

    asmirt_activity_id = db.Column(db.Integer, primary_key=True)
    activity_type = db.Column(db.String(255))
    activity = db.Column(db.String(255))
    alt_text = db.Column(db.String(255))
    activity_points = db.Column(db.Integer)
    per_unit = db.Column(db.String(255))

    @classmethod
    def find_by_activity_type(cls, activity_type: str):
        return cls.query.filter_by(activity_type=activity_type).all()

schema/lookup.py

from ma import ma
from models.lookup import LookupModel


class LookupSchema(ma.ModelSchema):
    class Meta:
        model = LookupModel
        dump_only = ("asmirt_activity_id",)

resource/lookup.py

from flask_restful import Resource
from models.lookup import LookupModel
from schemas.lookup import LookupSchema
from flask_jwt_extended import jwt_required
from flask import jsonify

class LookupActivities(Resource):
    @classmethod
    def get(cls, activity_type):
        data = LookupModel.find_by_activity_type(activity_type=activity_type)
        print(data)
        print(data[1].activity)
        if data:
            return {"activities": lookup_schema_list.dump(data)}, 200

        return {'message', 'No activities in that group'}

对于此示例，它将更改数据库中的值 2.5 但输出 2。在其他示例中，我将收到错误消息 Object Decimal is not serializable。有谁知道是什么原因造成的以及如何解决？

Answer 1

您的模型列没有小数声明。我猜您正在尝试向/从整数声明的列中插入/获取十进制数据。尝试将该列声明为十进制。

Answer 2

在您的 ma.ModelSchema class 中，您需要像这样覆盖十进制值：

from flask_marshmallow.fields import fields

class LookupSchema(ma.ModelSchema):
    per_unit = fields.Float()

    class Meta:
        model = LookupModel
        dump_only = ("asmirt_activity_id",)

现在您可以序列化 per_unit 属性。对所有属性重复此操作。您可以使用 Decimal 而不是 Float。

别忘了：在你的db.model中，per_unit必须是浮点数，比如：per_unit = db.Column(db.Float())

flask-marshmallow 去掉小数点

flask-marshmallow dropping the decimal point

python

flask

marshmallow