query from postgresql using python as dictionary

It’s normal: when you call .fetchall() method returns list of tuples. But if you write

type(cur.fetchone())

it will return only one tuple with type:

<class 'psycopg2.extras.DictRow'>

After this you can use it as list or like dictionary:

cur.execute('SELECT id, msg FROM table;')
rec = cur.fetchone()
print rec[0], rec['msg']

You can also use a simple cursor iterator:

res = [json.dumps(dict(record)) for record in cursor] # it calls .fetchone() in loop

Tnx a lot Andrey Shokhin ,

full answer is:

#!/var/bin/python 
import psycopg2
import psycopg2.extras
conn = psycopg2.connect("dbname=uniart4_pr host=localhost user=user password=password")
cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
cur.execute ("select * from port")
ans =cur.fetchall()
ans1 = []
for row in ans:
    ans1.append(dict(row))

print ans1  #actually it's return

Perhaps to optimize it further we can have

#!/var/bin/python 
import psycopg2
import psycopg2.extras

def get_dict_resultset(sql):
    conn = psycopg2.connect("dbname=pem host=localhost user=postgres password=Drupal#1008")
    cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    cur.execute (sql)
    ans =cur.fetchall()
    dict_result = []
    for row in ans:
        dict_result.append(dict(row))
    return dict_result

sql = """select * from tablename"""
return get_dict_resultset(sql)

For me when I convert the row to dictionary failed (solutions mentioned by others)and also could not use cursor factory.
I am using PostgreSQL 9.6.10, Below code worked for me but I am not sure if its the right way to do it.

    def convert_to_dict(columns, results):
    """
    This method converts the resultset from postgres to dictionary
    interates the data and maps the columns to the values in result set and converts to dictionary
    :param columns: List - column names return when query is executed
    :param results: List / Tupple - result set from when query is executed
    :return: list of dictionary- mapped with table column name and to its values
    """

    allResults = []
    columns = [col.name for col in columns]
    if type(results) is list:
        for value in results:
            allResults.append(dict(zip(columns, value)))
        return allResults
    elif type(results) is tuple:
        allResults.append(dict(zip(columns, results)))
        return allResults

Way to use it:

conn = psycopg2.connect("dbname=pem host=localhost user=postgres,password=Drupal#1008")
cur = conn.cursor()
cur.execute("select * from tableNAme")

resultset = cursor.fetchall()
result = convert_to_dict(cursor.description, resultset)
print(result)

resultset = cursor.fetchone()
result = convert_to_dict(cursor.description, resultset)
print(result)

In addition to just return only the query results as a list of dictionaries, I would suggest returning key-value pairs (column-name:row-value). Here my suggestion:

import psycopg2
import psycopg2.extras

    conn = None
    try:
        conn = psycopg2.connect("dbname=uniart4_pr host=localhost user=user password=password")

        with conn.cursor(cursor_factory=psycopg2.extras.DictCursor) as cursor:
            cursor.execute("SELECT * FROM table")
            column_names = [desc[0] for desc in cursor.description]
            res = cursor.fetchall()
            cursor.close()
        return map(lambda x: dict(zip(column_names, x)), res))

    except (Exception, psycopg2.DatabaseError) as e:
        logger.error(e)
    finally:
        if conn is not None:
            conn.close()

Contents of ‘./config.py’

        #!/usr/bin/python
        PGCONF = {
            "user": "postgres", 
            "password": "postgres", 
            "host": "localhost", 
            "database": "database_name"
        }

contents of ‘./main.py’

        #!/usr/bin/python

        from config import PGCONF

        import psycopg2
        import psycopg2.extras

        # open connection
        conn = psycopg2.connect(**PGCONF)
        cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)

        # declare lambda function
        fetch_all_as_dict = lambda cursor: [dict(row) for row in cursor]

        # execute any query of your choice
        cur.execute("""select * from table_name limit 1""")

        # get all rows as list of dicts
        print(fetch_all_as_dict(cur))

        # close cursor and connection
        cur.close()
        conn.close()

There is a built in solution to get your result as a collection of dictionary:

from psycopg2.extras import RealDictCursor
cur = conn.cursor(cursor_factory=RealDictCursor)

Modified from: https://www.peterbe.com/plog/from-postgres-to-json-strings, copyright 2013 Peter Bengtsson