connection.rst

The Connection object

This documentation section outlines different attributes, methods, and behaviors of the crate.client.connection.Connection object.

The examples use an instance of ClientMocked instead of a real Client instance. This allows us to verify the examples without needing a real database connection.

Table of Contents

• connect()
• cursor()
• close()

connect()

This section sets up a connection object, and inspects some of its attributes.

>>> from crate.client import connect
>>> from crate.testing.util import ClientMocked

>>> connection = connect(client=ClientMocked())
>>> connection.lowest_server_version.version
(2, 0, 0)

cursor()

Calling the cursor() function on the connection will return a cursor object:

>>> cursor = connection.cursor()

Now we are able to perform any operation provided by the cursor object:

>>> cursor.rowcount
-1

close()

Now we close the connection:

>>> connection.close()

The connection will be unusable from this point. Any operation attempted with the closed connection will raise a ProgrammingError:

>>> cursor = connection.cursor()
Traceback (most recent call last):
...
crate.client.exceptions.ProgrammingError: Connection closed

>>> cursor.execute('')
Traceback (most recent call last):
...
crate.client.exceptions.ProgrammingError: Connection closed

>>> connection.commit()
Traceback (most recent call last):
...
crate.client.exceptions.ProgrammingError: Connection closed