return SQL table as JSON in python

Question

I'm playing around with a little web app in web.py, and am setting up a url to return a JSON object. What's the best way to convert a SQL table to JSON using python?

Answer 1

Here is a really nice example of a pythonic way to do that:

import json
import psycopg2

def db(database_name='pepe'):
    return psycopg2.connect(database=database_name)

def query_db(query, args=(), one=False):
    cur = db().cursor()
    cur.execute(query, args)
    r = [dict((cur.description[i][0], value) 
               for i, value in enumerate(row)) for row in cur.fetchall()]
    cur.connection.close()
    return (r[0] if r else None) if one else r

my_query = query_db("select * from majorroadstiger limit %s", (3,))

json_output = json.dumps(my_query)

You get an array of JSON objects:

>>> json_output
'[{"divroad": "N", "featcat": null, "countyfp": "001",...

Or with the following:

>>> j2 = query_db("select * from majorroadstiger where fullname= %s limit %s",
 ("Mission Blvd", 1), one=True)

you get a single JSON object:

>>> j2 = json.dumps(j2)
>>> j2
'{"divroad": "N", "featcat": null, "countyfp": "001",...