sqla-raw 0.5.0

A tiny library for submitting raw SQL via SQLAlchemy

sqla-raw

An opinionated, minimalist library for fetching data from a SQLAlchemy connection, when you don't need or want an ORM. You know how to write SQL; sqla-raw makes it E-Z to send that raw SQL to your database and get results, saving a lot of DBAPI boilerplate and providing a simple and consistent interface with a result format that is straightfoward to introspect.

Really not much more than a single method (raw.db.result()) that submits raw SQL via a SQLAlchemy Engine connection. By default, db.result() returns all results as a list of dictionaries, keyed by column names. (See 'Usage' below for other options)

As a convenience, result_from_file() is about the same except that it reads your query from a given path, rather than taking a SQL string argument directly. Contents of the file are handed off to result() so the rest functions identitically.

Engine instantiation is handled implicitly by the first call to result(); any subsequent calls use a connection from the pool. The connection string for the Engine is set by DATABASE_URL in the environment. All other Engine settings use SQLAlchemy defaults. (Affording explicit creation and disposal of the Engine and exposing the setting of other parameters might be a useful area for further development, if it can be kept simple.)

Installation

pip install sqla-raw[pg]

Usage

Configure your database connection string by setting $DATABASE_URL in your environment.

>>> from raw import db
>>> x = db.result('select version()');
>>> x
[{'version': 'PostgreSQL 10.10 on x86_64-apple-darwin14.5.0, compiled by Apple LLVM version 7.0.0 (clang-700.1.76), 64-bit'}]

Because it's SQLAlchemy, you can safely use named parameters in your SQL string with colon-prepended :key format, and assign values in kwargs.

>>> db.result('select :foo as bar', foo='baz')
[{'bar': 'baz'}]

Jinja templating

You can also use Jinja2 templating syntax to interpolate the query, if desired. db.result() inspects the query for template tags ("{%.*%}") and renders the template to SQL before submitting if tags are present. (It uses a SandboxedEnvironment for some measure of injection safety, but avoid this option with untrusted inputs, for obvious reasons.)

Options

Passing argument returns to db.result() (or result_from_file()) overrides the default result formatting: returns="tuples" brings back a list of tuples with row values instead of dictionaries, and returns="proxy" returns the plain SQLAlchemy ResultProxy object directly, for further handling by the caller. The "proxy" option allows access to methods (e.g. fetchone() or fetchmany() ) that sqla-raw default usage hides behind its facade; it can also be good for SQL statements (such as inserts without returning or DDL) that are not expected to return results — although by default these will return an empty list.

Tests

pytest tests are located in tests/. Install test prerequisites with pip install -r tests/requirements.txt; then they can be run with: python setup.py test