從Flask的SQLAlchemy返回JSON對象以獲取3個相關表

Question

我得到了這個模型model.py。 它具有3個表，Test，Area，Issue一個測試具有多個區域，每個區域都有許多問題：

from sqlalchemy import Column, ForeignKey, Integer, String, DateTime
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
from sqlalchemy import create_engine
from sqlalchemy.sql import func

Base = declarative_base()


class Test(Base):

    __tablename__ = 'test'
    id = Column(Integer, primary_key=True)
    type = Column(String(30), nullable=False)
    number = Column(String(30))
    status = Column(String(30), nullable=False)
    start_date = Column(DateTime(timezone=True), server_default=func.now())
    closed_date = Column(DateTime(timezone=True), server_default=func.now())
    description = Column(String(500))
    contact = Column(String(200))

    @property
    def serialize(self):
        # Returns object data in easily serializable format
        return{
            'id': self.id,
            'type': self.type,
            'number': self.number,
            'status': self.status,
            'start_date': self.start_date,
            'closed_date': self.closed_date,
            'description': self.description,
            'contact': self.contact
        }


class Area(Base):

    __tablename__ = 'area'
    id = Column(Integer, primary_key=True)
    name = Column(String(30), nullable=False)
    test_id = Column(Integer, ForeignKey('test.id'))
    test = relationship(Test, backref='areas')

    @property
    def serialize(self):
        # Returns object data in easily serializable format
        return{
            'name': self.name,
            'id': self.id
        }


class Issue(Base):

    __tablename__ = 'issue'
    name = Column(String(80), nullable=False)
    id = Column(Integer, primary_key=True)
    reference_number = Column(String(20), nullable=True)
    status = Column(String(30), nullable=False)
    area_id = Column(Integer, ForeignKey('area.id'))
    area = relationship(Area, backref='issues')

    @property
    def serialize(self):
        # Returns object data in easily serializable format
        return{
            'name': self.name,
            'id': self.id,
            'reference_number': self.price,
            'status': self.status
        }


engine = create_engine('sqlite:///appsecurity.db?check_same_thread=False')
Base.metadata.create_all(engine)

我想返回一個查詢結果的JSON，該查詢將返回，包含其所有區域以及每個區域內的所有問題的測試：

這是SQLAlchemy查詢：

def getTestWithAreasAndIssues(id):
    test = (session.query(Test, Area, Issue)
            .join(Area)
            .join(Issue)
            .options(
                joinedload(Test.areas).
                joinedload(Area.issues)
            )
            .filter(Test.id == id)
            .filter(Test.id == Area.test_id)
            .filter(Area.id == Issue.area_id)
            ).all()
    return test

我認為這是正確的，並且等效於以下sqlite3查詢：

sqlite> select * from test, area, issue where area.test_id=test.id and issue.area_id=area.id and test.id=4;

4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|12|Encryption|4|Weak Encryption|1|701|12|N
4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|12|Encryption|4|ATS not in used|2|702|12|N
4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|13|Authentication|4|Basic Authentication|3|701|13|N
4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|20|Information|4|Sensitive Information on disk|4|103|20|N
4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|20|Information|4|Password stored in cookies |5|104|20|N
4|Web|Test 11111|Open|2018-07-23 01:59:11.932234|2018-07-23 01:59:11|Second Test With Issues Third Attemp|david@no.us|20|Information|4|Not rate limited in API resources|6|701|20|N
sqlite> 

為了澄清更多，這里是sqlalchemy的結果：

這是SQLALchemy的響應

[(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e8210>, <model.Issue object at 0x7f15322e8450>), 
(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e8210>, <model.Issue object at 0x7f15322e8710>), 
(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e82d0>, <model.Issue object at 0x7f15322e83d0>), 
(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e8650>, <model.Issue object at 0x7f15322e8950>), 
(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e8650>, <model.Issue object at 0x7f15322e88d0>), 
(<model.Test object at 0x7f15322e8190>, <model.Area object at 0x7f15322e8650>, <model.Issue object at 0x7f15322e8850>)]

有人可以幫助我找到某種從中返回JSON對象的方法嗎？

Answer 1

這個文件沒有問題，我遇到了一個問題，並且正在調用錯誤的函數，但是文件本身還可以，我可以正確地調用json.dumps（result）並將正確的JSON返回到flask中

response = make_response（json.dumps（result，cls = MyEncoder1），200）response.headers ['Content-Type'] ='application / json'返回響應

我使用cls參數修復了編碼日期時間的問題，因為json.dumps在解碼datetime參數時失敗

請在此處查看編碼器的代碼

    #!/usr/bin/env python3
from datetime import datetime
import json

class MyEncoder1(json.JSONEncoder):
    def default(self, obj):
        """
        default method is used if there is an unexpected object type.
        datetime will be converted to string
        """
        if isinstance(obj, datetime):
            obj = str(obj)
        else:
            obj = super(MyEncoder1, self).default(obj)
        print obj
        return obj

謝謝，我希望這篇文章能對任何使用Flask和SQLAlchemy進行JSON操作的人有所幫助。

我會想看看對本規范的改進，哪些可以做得更好，哪些可以做得更好