sheba 0.0.4

Motivation

I can write SQL faster than I can figure out the various library and ORM abstraction layers. Writing SQL directly in code is pretty disgusting. So I stole an idea from the Axamol SQL Library and along with a couple updates have created this library.

What is it?

First, we’ll consider some basic query definitions:

>>> queries = """
... name: create_roles_table
... type: update
... sql: |
...     CREATE  TABLE roles
...     (
...         scene   text,
...         name    text,
...         actor   text,
...         UNIQUE(scene, name)
...     )
... ---
... name: add_role
... type: update
... sql: |
...     INSERT
...     INTO    roles(scene, name, actor)
...     VALUES  (${scene}, ${name}, ${actor})
... ---
... name: list_roles
... sql: |
...     SELECT  name,
...             actor
...     FROM    roles
...     ORDER   BY
...             name ASC
... ---
... name: get_role_attr
... sql: |
...     SELECT  ${col | ident}
...     FROM    roles
...     WHERE   name = ${name}
... """
>>>

This is a YAML file that defines a couple queries for working with a simple table that lists scenes, roles, and actors. Generally, you’ll want to define your queries in a file in your Python package and use the static method sheba.Library.from_file(path) to load the queries.

Now, to use these in some code:

>>> import sheba
>>> lib = sheba.Library(queries)
>>> conn = sheba.connect(lib, 'sqlite3', ':memory:')

Now that we have a connection, lets create the roles table:

>>> conn.u.create_roles_table()
-1

The -1 is due to DDL statements not returning row information. I could technically create a third class of statement types so avoid this, but in the not doctest world you can just ignore that return value.

Next we’ll insert a couple rows:

>>> conn.u.add_role(scene="Parrot Sketch", name="MR PRALINE", actor="John Cleese")
1
>>> conn.u.add_role(scene="Parrot Sketch", name="SHOP OWNER", actor="Machale Palin")
1
>>> conn.u.add_role(scene="Parrot Sketch", name="DEAD PARROT", actor="Fake Parrot")
1

Yep, it’s that simple. And lastly, we’ll list the roles in the table:

>>> for row in conn.q.list_roles():
...     print "Name: %(name)s Actor: %(actor)s" % row
...
Name: DEAD PARROT Actor: Fake Parrot
Name: MR PRALINE Actor: John Cleese
Name: SHOP OWNER Actor: Machale Palin

As they say, “Wicked awesome.”

Possible Query Attributes

The example above only used name, type, and sql. Only name and sql are absolutely required. The full list of attributes is:

• name - The name used to reference this query from Python

• desc - An explanation of the query for documentation.

• type - query or update. Defaults to query.

• dbs - A list of database names that this SQL will work with. The default

  value is None which is interpreted as “Use this query when no SQL has been defined for the current connections database connection.”

• sql - The actual query. SQL is passed through Mako with access to

  any parameter names that were provide to the query. To bind a parameter in a query, simply print the value with standard Mako syntax like ${my_parameter_name}. Sheba will automatically replace it with the proper bind variable syntax and pass the supplied value onto the database connection.

Identifiers in SQL

If you’re feeling particularly precocious there’s support for dynamically setting identifier names in SQL statements.

Given the following YAML query:

name: get_role_attr
sql: |
    SELECT ${col | ident}
    FROM    roles
    WHERE   name = ${name}

You can then execute this query like such:

>>> for row in conn.q.get_role_attr({"col": "actor", "name": "MR PRALINE"}):
...     print "%(actor)s" % row
...
John Cleese

License

Released under the MIT license. See the LICENSE file for more details.