格式资料python sqlalchemy 查询结果转化为 Json格式

最近使用开辟的过程中出现了一个小问题，顺便记录一下原因和方法--格式资料

      最近，给自己开辟的软件平台开辟第三方调用的API，如果返回结果集是json格式，其他语言开辟就绝对便利一些，网上找了好多资料没有找到特殊合适的，最后下决心根据网上的资料转变自己写一个通用的。

    此方法，主要应用场景是，Python 数据库框架 sqlalchemy 查询结果，转化成json格式。

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# -*- coding: utf-8 -*-

import os

import json

import threading

 

from xml.dom import minidom

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy.orm import sessionmaker, scoped_session

from sqlalchemy import (create_engine,MetaData,Column,Integer,String)

from sqlalchemy import func

from sqlalchemy.sql.expression import and_, or_

from sqlalchemy import Table, Column, Integer, String, Text, DateTime, MetaData, ForeignKey, Boolean

from datetime import datetime

import time,uuid,re



Base = declarative_base()



#主机模型

class VirtualMachineContainer(Base):

    __tablename__ = 'virtual_machine_containers'



    id = Column(Integer, primary_key = True)

    hostname = Column(String(255))

    uuid = Column(String(255))

    address = Column(String(255))

    port = Column(Integer)

    status = Column(String(255))

    owner_id = Column(Integer)

    group_id = Column(Integer)

    cluster_id = Column(Integer)

    running_time = Column(Integer)

    cpu_type = Column(String(255))

    cpu_num = Column(String(255))

    cpu_usage = Column(String(255))

    mem_total = Column(String(255))

    mem_free = Column(String(255))

    disk_device = Column(String(255))

    disk_total = Column(String(255))

    disk_free = Column(String(255))

    nics_num = Column(Integer)

    net_ifname = Column(String(255))

    net_tx = Column(String(255))

    net_rx = Column(String(255))

    vm_name = Column(String(255))

    vm_state = Column(String(255))

    vcpu_usage = Column(String(255))

    vmem_total = Column(String(255))

    vmem_free = Column(String(255))

    vdisk_read = Column(String(255))

    vdisk_write = Column(String(255))

    vif_tx = Column(String(255))

    vif_rx = Column(String(255))

    field_metadata = Column('metadata', String(255))

    created_at = Column(DateTime, default=datetime.now)

    updated_at = Column(DateTime, default=datetime.now, onupdate=datetime.now)

    vm_uuid = Column(Text)

    capability = Column(String(255))

    vdisk_names = Column(String(255))

    vif_names = Column(String(255))

    all_pair_ping = Column(Text)

    vnc_port = Column(String(255))

    vm_cnt = Column(Integer)

    respool_cnt = Column(String(255))

    reserved = Column(String(255))

    host_desc = Column(Text)

    host_vendor_name = Column(String(255))

    host_type = Column(String(255))

    oper_system_vendor_name = Column(String(255))

    oper_system_name = Column(String(255))

    uuid_bios = Column(String(255))

    dns = Column(String(255))

    cpu_core_num = Column(String(255))

    cpu_thread_num = Column(String(255))

    diskarray_num = Column(String(255))

    datacenter_id = Column(Integer, ForeignKey('data_centers.id'))

    user_name = Column(String(255))

    password = Column(String(255))

    status_flag = Column(Integer(1))

    hardware_id = Column(String(16))



def get_Session():

    #engine = create_engine('mysql://root:[email protected]/ivcs_portal?charset=utf8')

    engine = create_engine('mysql://root:@172.30.36.7/ivcs_portal?charset=utf8')

    Base.metadata.create_all(engine)

    Session =sessionmaker( autocommit=False, autoflush=False, bind=engine)

    return Session

from sqlalchemy.ext.declarative import DeclarativeMeta

class AlchemyEncoder(json.JSONEncoder):

    def default(self, obj):

        if isinstance(obj.__class__, DeclarativeMeta):

            # an SQLAlchemy class

            fields = {}

            for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:

                data = obj.__getattribute__(field)

                try:

                    if isinstance(data, datetime): 

                        data=data.strftime('%Y-%m-%d %H:%M:%S') 

                    json.dumps(data) # this will fail on non-encodable values, like other classes

                    fields[field] = data

                except TypeError:

                    fields[field] = None

            # a json-encodable dict

            return fields

    

        return json.JSONEncoder.default(self, obj)

def new_alchemy_encoder():

    _visited_objs = []

    class AlchemyEncoder(json.JSONEncoder):

        def default(self, obj):

            if isinstance(obj.__class__, DeclarativeMeta):

                # don't re-visit self

                if obj in _visited_objs:

                    return None

                _visited_objs.append(obj)



                # an SQLAlchemy class

                fields = {}

                for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:

                    data = obj.__getattribute__(field)

                    try:

                        if isinstance(data, datetime): 

                            data=data.strftime('%Y-%m-%d %H:%M:%S') 

                        json.dumps(data) # this will fail on non-encodable values, like other classes

                        fields[field] = data

                    except TypeError:

                        fields[field] = None

                return fields



            return json.JSONEncoder.default(self, obj)

    return AlchemyEncoder



def testjson():

    session=get_Session()()

    vmcs = session.query(VirtualMachineContainer).all()

    try:

        

        Hosts =[]

        for vmc in vmcs:

            #print json.dumps(vmc, cls=AlchemyEncoder)

            Hosts.append(vmc)

        print json.dumps(Hosts, cls=new_alchemy_encoder(), check_circular=False)

    except Exception, e:

        print e  



if __name__ == '__main__':

    testjson()

    
 

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