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Flask搭建api服务
2022-07-07 15:34:00 【python与大数据分析】
Flask是一个使用 Python 编写的轻量级 Web 应用框架，很适合个人开发，我们在此处做一个接口。
为方便调试，本文使用get接口方式。get接口十分简单，不需要上传任何数据，在路径后面添加一个get方法就可以用，返回的是字符串。
本文只是Flask开发的接口的初步文档，从最简单的接口开发到稍微复杂一些的接口，后续如有时间，会逐步完善，包括token鉴权、跨域认证、蓝图应用、日志管理等等。
第一步，首先在configs中配置数据源
configs.py
HOST = '127.0.0.1'
PORT = '5432'
DATABASE = 'runoobdb'
USERNAME = 'postgres'
PASSWORD = '*****'
# 配置主数据库
DB_URI = "postgresql+psycopg2://{username}:{password}@{host}:{port}/{db}".format(username=USERNAME, password=PASSWORD,
host=HOST, port=PORT, db=DATABASE)
# SQLALCHEMY_DATABASE_URI = 'postgresql+psycopg2://postgres:*****@127.0.0.1:5432/runoobdb'
# 连接其他数据库
SQLALCHEMY_BINDS = {
'xxxdb': 'postgresql+psycopg2://postgres:[email protected]:5432/lincms3',
'yyydb': 'postgresql+psycopg2://postgres:[email protected]:5432/lincms4',
'zzzdb': 'sqlite:///users.db'
}
SQLALCHEMY_DATABASE_URI = DB_URI
SQLALCHEMY_TRACK_MODIFICATIONS = False
SQLALCHEMY_ECHO = True第二步，在exts中定义全局db
exts.py
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()第三步，构造了一个flaskutils，在这里定义一些接口应用到的公共类，比如数据转码，将数据集转换为json，解析url逗号参数等等，后续将在此基础上拓展功能。
flaskutils.py
import decimal
import numpy as np
import json, datetime,configparser
class DataEncoder(json.JSONEncoder):
"""数据转码类 """
def default(self, obj):
"""针对无法转json的数据类型进行转码
目前支持的转码类型 1、将Numpy的intger,floating转为int和float
2、将Numpy的ndarray转为list
3、将np.datetime64转化为字符串前10位 4、将datetime.datetime转化为"%Y-%m-%d %H:%M:%S"
5、将datetime.date转化为"%Y-%m-%d"
6、将bytes转化为utf-8字符串
入参:
obj: 数据对象
出参:
转化后的数据
异常:
无 """
if isinstance(obj, np.integer):
return int(obj)
elif isinstance(obj, np.floating):
return float(obj)
elif isinstance(obj, np.ndarray):
return obj.tolist()
elif isinstance(obj, np.datetime64):
return str(obj)[:10]
elif isinstance(obj, datetime.datetime):
return obj.strftime("%Y-%m-%d %H:%M:%S")
elif isinstance(obj, datetime.date):
return obj.strftime("%Y-%m-%d")
elif isinstance(obj, decimal.Decimal):
return float(obj)
elif isinstance(obj, bytes):
return str(obj, encoding='utf-8')
else:
return json.JSONEncoder.default(self, obj)
def getsqlresultjson(db, sql,params={}):
"""根据db和sql语句，将结果集转换为json格式
根据db和sql语句，将结果集转换为json格式
第一步：根据cursor获取元数据，生成键值列表
第二步：遍历结果集，将键值列表和结果集组装成字典，加入列表
第三步：将列表通过DataEncoder进行转码
入参:
db: 数据库实例.
sql: 待运行的SQL语句
出参:
Json格式:
举例： {'Serak': ('Rigel VII', 'Preparer'),
'Zim': ('Irk', 'Invader'),
'Lrrr': ('Omicron Persei 8', 'Emperor')}
异常:
无 """
resultdict = []
cursor = db.session.execute(sql,params=params).cursor
resultproxy = db.session.execute(sql,params=params).fetchall()
# 获取元数据
colname = [i[0] for i in cursor.description]
# 获取结果集，组成字典，加入列表
for rowproxy in resultproxy:
rowresult = dict(zip(colname, rowproxy))
resultdict.append(rowresult)
# 生成json格式
jsonstr = json.dumps(resultdict, cls=DataEncoder)
return jsonstr
def parasecommaparamtolist(param):
'''
处理in传递参数，in传递参数可适用于两种传递方式，逗号传递参数或参数传递
此处主要是处理,逗号传递参数，返回为list
# http://127.0.0.1:5000/getresultbysqlgetparaminbylist?sqlid=sql10&begindate=2018&enddate=2020&kpicode=03010101
# http://127.0.0.1:5000/getresultbysqlgetparaminbylist?sqlid=sql10&begindate=2018&enddate=2020&kpicode=03010101&kpicode=031111111
# http://127.0.0.1:5000/getresultbysqlgetparaminbylist?sqlid=sql10&begindate=2018&enddate=2020
# http://127.0.0.1:5000/getresultbysqlgetparaminbylist?sqlid=sql10&begindate=2018&enddate=2020&kpicode=03010101,222222222
# http://127.0.0.1:5000/getresultbysqlgetparaminbylist?sqlid=sql10&begindate=2018&enddate=2020&kpicode=03010101&kpicode=03010101
:param param:
:return:
字符串列表 '''
result = []
for val in param.split(','):
if val:
result.append(val)
return result第四步，在app文件构建初始版本
app.py
import configs
from exts import db
from flask import Flask
from flaskutils import *
from flask import request,jsonify
app = Flask(__name__)
# 加载配置文件
app.config.from_object(configs)
app.debug = True
db.init_app(app)
if __name__ == '__main__':
print(app.url_map)
app.run(host='0.0.0.0', port=8080)第五步，在app文件中配置sql语句，原本想尝试一下mybis类型的配置文件，后来决定简化；主要包括三条sql，第一条不需要传参，第二条传递常规参数，第三条传递in参数，尤其是in参数，基本上网上找到的方法都不可靠，本文算是原创吧。
sqldict={}
sqldict['sql1'] = """select a.*
from kpi_value a
where a.kpicode in ('01010101','02010101','03010101')
and a.datelevel='01'
and a.regionlevel='02'
"""
sqldict['sql2'] = """select a.*
from kpi_value a
where a.kpicode in ('01010101','02010101','03010101')
and a.datelevel='01'
and a.regionlevel='02'
and a.datecode>=:begindate and a.datecode<=:enddate
"""
sqldict['sql3'] = """select a.*
from kpi_value a
and a.datelevel='01'
and a.regionlevel='02'
and a.datecode>=:begindate and a.datecode<=:enddate
and a.kpicode in :kpicode
"""1、构造第一个最简单sql返回接口，不需要传递sql参数，但需要传递sqlid参数
@app.route('/getresultbysql', methods=['GET', 'POST'])
def index1():
sqlid = request.args.get('sqlid')
sqltext=sqldict[sqlid]
jsonstr = getsqlresultjson(db,sqltext)
return jsonstr, 200, {"Content-Type": "application/json"}2、构造一个sql内部传参的接口，通过字典参数方式
@app.route('/getresultbysqlparam', methods=['GET', 'POST'])
def index2():
sqlid = request.args.get('sqlid')
sqltext=sqldict[sqlid]
params = {"begindate": '2017',"enddate":'2019'}
jsonstr = getsqlresultjson(db,sqltext,params)
return jsonstr, 200, {"Content-Type": "application/json"}3、通过url进行sql参数的传递。
@app.route('/getresultbysqlgetparam', methods=['GET', 'POST'])
def index3():
sqlid = request.args.get('sqlid')
begindate = request.args.get('begindate')
enddate = request.args.get('enddate')
sqltext=sqldict[sqlid]
params = {"begindate": begindate,"enddate":enddate}
jsonstr = getsqlresultjson(db,sqltext,params)
return jsonstr, 200, {"Content-Type": "application/json"}4、通过url进行sql参数的传递，不过不传递in参数，而是在路由函数汇总内部指定in参数
@app.route('/getresultbysqlgetparamin', methods=['GET', 'POST'])
def index4():
sqlid = request.args.get('sqlid')
sqlid='sql3'
begindate = request.args.get('begindate')
enddate = request.args.get('enddate')
sqltext=sqldict[sqlid]
incond = ['01010101', '03010101']
params = {"begindate": begindate,"enddate":enddate,'kpicode':tuple(incond)}
jsonstr = getsqlresultjson(db,sqltext,params)
return jsonstr, 200, {"Content-Type": "application/json"}5、通过url进行in参数和普通参数的传递，这里可以支持两种方式，一种是&aa=xxx&aa=yyy，一种是aa=xxx,yyy。
@app.route('/getresultbysqlgetparaminbylist', methods=['GET', 'POST'])
def index5():
sqlid = request.args.get('sqlid')
sqlid='sql3'
begindate = request.args.get('begindate')
enddate = request.args.get('enddate')
incond=request.args.getlist('kpicode')
if len(incond) == 1 and ',' in incond[0]:
incond = parasecommaparamtolist(incond[0])
sqltext=sqldict[sqlid]
params = {"begindate": begindate,"enddate":enddate,'kpicode':tuple(incond)}
jsonstr = getsqlresultjson(db,sqltext,params)
return jsonstr, 200, {"Content-Type": "application/json"}6、标准化接口响应返回结果。
@app.route('/getresultbysqlgetparaminbylistresponse', methods=['GET', 'POST'])
def index6():
retinfo={}
errorflag=False
retinfo['returncode'] = 200
retinfo['returndata'] = ''
retinfo['returninfo'] = '处理成果'
sqlid = request.args.get('sqlid')
begindate = request.args.get('begindate')
enddate = request.args.get('enddate')
incond = request.args.getlist('kpicode')
if len(incond) == 1 and ',' in incond[0]:
incond = parasecommaparamtolist(incond[0])
if not incond:
retinfo['returninfo']=retinfo['returninfo'] +'未传入KPI编码'
errorflag=True
if not begindate:
retinfo['returninfo'] = retinfo['returninfo'] + '未传入开始时间'
errorflag=True
if not enddate:
retinfo['returninfo'] = retinfo['returninfo'] + '未传入结束时间'
errorflag=True
if begindate>enddate:
retinfo['returninfo'] = retinfo['returninfo'] + '开始时间大于结束时间'
errorflag=True
if errorflag==True:
retinfo['returncode'] = 400
response = jsonify(retinfo)
response.status_code = 400
return response
sqltext = sqldict[sqlid]
params = {"begindate": begindate, "enddate": enddate, 'kpicode': tuple(incond)}
jsonstr = getsqlresultjson(db, sqltext, params)
retinfo['returndata'] = jsonstr
response = jsonify(retinfo)
response.status_code = 200
return response最后，谢谢关注，谢谢支持！
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