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A simple wrapper for Python psycopg2

Project description

An ultra simple wrapper over Python psycopg2 with support for basic SQL functionality.

Installation

With pip or easy_install:

pip install pg_simple

or:

easy_install pg_simple

or from the source:

python setup.py install

Basic Usage

Initializing the connection pool:

import pg_simple

pg_simple.config_pool(max_conn=5,
                      expiration=1, # idle timeout = 1 minute
                      host='localhost',
                      port=5432,
                      database='pg_simple',
                      user='postgres',
                      password='secret')

or, using dsn:

pg_simple.config_pool(max_conn=5,
                      expiration=1,
                      dsn='dbname=pg_simple user=postgres password=secret')

or, using db_url:

pg_simple.config_pool(max_conn=5,
                      expiration=1,
                      db_url= 'postgres://username:password@hostname:port/database')

Connecting to the posgtresql server:

import sys
import pg_simple

db = pg_simple.PgSimple(log=sys.stdout,
                        log_fmt=lambda x: '>> %s' % (x if isinstance(x, str) else x.query),
                        nt_cursor=True)

Raw SQL execution:

>>> db.execute('SELECT tablename FROM pg_tables WHERE schemaname=%s and tablename=%s', ['public', 'books'])
<cursor object at 0x102352a50; closed: 0>

Dropping and creating tables:

db.drop('books')

db.create('books',
          '''
"id" SERIAL NOT NULL,
"type" VARCHAR(20) NOT NULL,
"name" VARCHAR(40) NOT NULL,
"price" MONEY NOT NULL,
"published" DATE NOT NULL,
"modified" TIMESTAMP(6) NOT NULL DEFAULT now()
'''
)

db.execute('''ALTER TABLE "books" ADD CONSTRAINT "books_pkey" PRIMARY KEY ("id")''')

Emptying a table or set of tables:

db.truncate('tbl1')
db.truncate('tbl2, tbl3', restart_identity=True, cascade=True)
db.commit()

Inserting a row:

for i in range(1, 10):
    db.insert("books",
              {"genre": "fiction",
               "name": "Book Name vol. %d" % i,
               "price": 1.23 * i,
               "published": "%d-%d-1" % (2000 + i, i)})

db.commit()

Updating rows:

with pg_simple.PgSimple() as db1:
    db1.update('books',
               data={'name': 'An expensive book',
                     'price': 998.997,
                     'genre': 'non-fiction',
                     'modified': 'NOW()'},
               where=('published = %s', [datetime.date(2001, 1, 1)]))

    db1.commit()

Deleting rows:

db.delete('books', where=('published >= %s', [datetime.date(2005, 1, 31)]))
db.commit()

Inserting/updating/deleting rows with return value:

row = db.insert("books",
                {"type": "fiction",
                 "name": "Book with ID",
                 "price": 123.45,
                 "published": "1997-01-31"},
                returning='id')
print(row.id)

rows = db.update('books',
                 data={'name': 'Another expensive book',
                       'price': 500.50,
                       'modified': 'NOW()'},
                 where=('published = %s', [datetime.date(2006, 6, 1)]),
                 returning='modified')
print(rows[0].modified)

rows = db.delete('books',
                 where=('published >= %s', [datetime.date(2005, 1, 31)]),
                 returning='name')
for r in rows:
    print(r.name)

Fetching a single record:

book = db.fetchone('books',
                   fields=['name', 'published'],
                   where=('published = %s', [datetime.date(2002, 2, 1)]))

print(book.name + 'was published on ' + book[1])

Fetching multiple records:

books = db.fetchall('books',
                    fields=['name AS n', 'genre AS g'],
                    where=('published BETWEEN %s AND %s', [datetime.date(2005, 2, 1), datetime.date(2009, 2, 1)]),
                    order=['published', 'DESC'],
                    limit=5,
                    offset=2)

for book in books:
    print(book.n + 'belongs to ' + book[1])

Database transactions:

with pg_simple.PgSimple() as _db:
    try:
        _db.execute('Some SQL statement')
        _db.commit()
    except:
        _db.rollback()

Project details


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