python+flask+postgresql 学习

1、安装PostgreSQL

去官网下载安装：http://www.postgresql.org/download/

2、安装psycopg2

是一个PostgreSQL数据库连接库

去http://www.stickpeople.com/projects/python/win-psycopg/ 下载安装

一开始是pip install postgresql安装的，但是安装不成功。

3、创建postgresql触发器

create or replace function notify_on_insert() returns trigger as $$
begin
PERFORM pg_notify('channel_'||new.channel,cast(row_to_json(new) as text));
return null;
end;
$$ language plpgsql;

create trigger notify_on_message_insert after insert ON message
for each row execute procedure notify_on_insert();

4、创建表结构：

CREATE TABLE "public"."message" (

"id" int4 DEFAULT nextval('message_id_seq'::regclass) NOT NULL,

"channel" int4 NOT NULL,

"source" text COLLATE "default" NOT NULL,

"context" text COLLATE "default" NOT NULL,

CONSTRAINT "message_pkey" PRIMARY KEY ("id")

)

WITH (OIDS=FALSE)

;

5、创建应用

import flask
import psycopg2
import psycopg2.extensions
import select

app = flask.Flask(__name__)

def stream_messages(channel):
conn = psycopg2.connect(database='MyTest',user='postgres',password='123456',host='localhost')
conn.set_isolation_level(psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT)

curs = conn.cursor()
curs.execute('LISTEN channel_%d;'%int(channel))

while True:
select.select([conn],[],[])
conn.poll()
while conn.notifies:
notify = conn.notifies.pop()
yield "data:"+notify.payload+"\n\n"

@app.route("/message/<channel>",methods=['GET'])
def get_messages(channel):
return flask.Response(stream_messages(channel),mimetype='text/event-stream')

if __name__ == "__main__":
app.run()