我是Flask和SQLAlchemy的新手，我花了很多时间尝试使用Flask url（不是flask_restful）使数据库查询以JSON形式显示。
我以为我可以通过使用n0nSmoker/SQLAlchemy-serializer来工作。它使用以下语法，通过选择我的Trade SQLAlchemy类的简单查询来工作：trades = Trade.query.all()
我能够毫无问题地返回trades.to_dict（）。
但是，由于我需要执行group_by，因此我需要使用db.session.query(Trade, Trade.exchange, Trade.trader.......等更灵活的语法，该方法停止了工作。
我已经查看了其他选项，例如检查系统，但它似乎超出了我的技能水平。另外，似乎像_asdict（）之类的某些方法在行级别上不可用。
我有点迷茫，不知道如何进行。任何帮助将不胜感激。
编辑：请求更多代码：app.py的顶部
from flask import Flask
from flask_restful import Resource, Api
from models import *
from flask_sqlalchemy import SQLAlchemy
from sqlathanor import FlaskBaseModel, initialize_flask_sqlathanor
app = Flask(__name__)
app.config.from_pyfile('config.py')
db = SQLAlchemy(model_class = FlaskBaseModel)
db = initialize_flask_sqlathanor(db)
class Trades(Resource):
def get(self):
return AllTrades()
api.add_resource(Trades,'/')
if __name__ == '__main__':
app.run(host="0.0.0.0")
来自
models.pyfrom app import db
class Trade(db.Model):
id = db.Column(db.Integer, primary_key=True)
exchange = db.Column(db.String(255))
trader = db.Column(db.String(255))
symbol = db.Column(db.String(255))
coin = db.Column(db.String(255))
order_id = db.Column(db.String(255))
price = db.Column(db.String(255))
qty = db.Column(db.String(255))
fee = db.Column(db.String(255))
fee_currency = db.Column(db.String(255))
order_time = db.Column(db.DateTime(timezone=False))
side = db.Column(db.String(255))
maker_taker = db.Column(db.String(255))
def AllTrades():
#t = Trade
# trades = db.session.query(
# t,
# t.exchange,
# t.trader,
# t.symbol,
# t.coin,
# db.func.sum(t.qty),
# db.func.sum(t.fee).label("fee"),
# t.fee_currency,
# t.order_id,
# t.order_time,
# t.maker_taker
# ).group_by(t.order_id).all()
trades = Trade.query.all()
trades = trades.to_json()
return trades
全栈跟踪
Traceback (most recent call last):
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1997, in __call__
return self.wsgi_app(environ, start_response)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_restful/__init__.py", line 273, in error_router
return original_handler(e)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1614, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_restful/__init__.py", line 273, in error_router
return original_handler(e)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1517, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1612, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/app.py", line 1598, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_restful/__init__.py", line 480, in wrapper
resp = resource(*args, **kwargs)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask/views.py", line 84, in view
return self.dispatch_request(*args, **kwargs)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_restful/__init__.py", line 595, in dispatch_request
resp = meth(*args, **kwargs)
File "/Users/foo/Sites/Reporting_dev/app.py", line 18, in get
return AllTrades()
File "/Users/foo/Sites/Reporting_dev/models.py", line 42, in AllTrades
trades = Trade.query.all()
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py", line 514, in __get__
return type.query_class(mapper, session=self.sa.session())
File "/Users/foo/anaconda3/lib/python3.6/site-packages/sqlalchemy/orm/scoping.py", line 74, in __call__
return self.registry()
File "/Users/foo/anaconda3/lib/python3.6/site-packages/sqlalchemy/util/_collections.py", line 1001, in __call__
return self.registry.setdefault(key, self.createfunc())
File "/Users/foo/anaconda3/lib/python3.6/site-packages/sqlalchemy/orm/session.py", line 2939, in __call__
return self.class_(**local_kw)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py", line 143, in __init__
bind = options.pop('bind', None) or db.engine
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py", line 877, in engine
return self.get_engine()
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py", line 887, in get_engine
state = get_state(app)
File "/Users/foo/anaconda3/lib/python3.6/site-packages/flask_sqlalchemy/__init__.py", line 570, in get_state
'The sqlalchemy extension was not registered to the current ' \
AssertionError: The sqlalchemy extension was not registered to the current application. Please make sure to call init_app() first.
最佳答案
我建议您看一两个星期前发布的新库，名为SQLAthanor。
它为SQLAlchemy模型添加了简单的序列化支持，并且如果您还使用Flask-SQLAlchemy，那么它也可以无缝地工作。
基本上，它的工作方式是这样的：
您可以（大概）已经定义了Trade模型。唯一的区别是您从SQLAthanor而不是从SQLAlchemy（或Flask-SQLAlchemy）导入declarative_base或基本模型。
您可以在定义模型时配置序列化规则。这基本上可以让您说“当我将交易序列化为JSON时，包括属性X，Y和Z，但不包括P，D和Q”。
执行查询，但是通常会执行。您大概会得到一个Trade实例的列表。现在，您可以通过调用<instance>.to_json()将每个实例序列化为JSON。
值得一提的是SQLAthanor：
支持与JSON，CSV，YAML和Python dict之间的序列化和反序列化
支持Column属性，关系，混合属性，关联代理和常规Python @properties的序列化/反序列化
支持在属性级别进行序列化/反序列化的自定义预处理/后处理功能（用于验证或类型强制）
支持在属性级别为特定格式启用/禁用序列化和反序列化（例如，接受入站密码，但从不包括入站密码）
可能值得一看。这里是（希望全面）文档的链接：http://sqlathanor.readthedocs.io/en/latest/
希望对您有所帮助，如果您有任何疑问或需要帮助以使其正常运行，请告诉我（或使用标签sqlathanor将问题发布到SO）
关于python - Flask + SQLAlchemy结果转换为JSON，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/51477961/