buildaquery 0.1.0

A Python-based query builder for PostgreSQL.

Build-a-Query

A Python-based query builder designed to represent, compile, and execute SQL queries using a dialect-agnostic Abstract Syntax Tree (AST). Initial support is focused on PostgreSQL.

Features

• Dialect-Agnostic AST: Build queries using high-level Python objects.
• Full DML Support: Create SELECT, INSERT, UPDATE, and DELETE statements.
• Advanced Querying: Support for CTEs (WITH), Subqueries, Set Operations (UNION, INTERSECT, EXCEPT), and Window Functions (OVER).
• Rich Expression Logic: Includes CASE expressions, IN, BETWEEN, and type casting.
• DDL Support: Basic schema management with CREATE TABLE and DROP TABLE.
• Visitor Pattern Traversal: Extensible architecture for analysis and compilation.
• Secure Compilation: Automatic parameterization to prevent SQL injection.
• Execution Layer: Built-in support for executing compiled queries via psycopg.

Installation

For Users

Install Build-a-Query via pip:

pip install buildaquery

Requirements:

• Python 3.12+
• PostgreSQL database: A running PostgreSQL instance (version 12+ recommended). You can set this up locally, via Docker, or use a cloud service.
  • Example with Docker: docker run --name postgres -e POSTGRES_PASSWORD=yourpassword -d -p 5432:5432 postgres:15
• psycopg (automatically installed as a dependency) - the PostgreSQL adapter for Python.
• python-dotenv (automatically installed as a dependency) - for loading environment variables from a .env file.

Environment Variables

To connect to your PostgreSQL database, set the following environment variables (or use a .env file with python-dotenv):

• DB_HOST: PostgreSQL host (e.g., localhost)
• DB_PORT: PostgreSQL port (e.g., 5432)
• DB_NAME: Database name (e.g., mydatabase)
• DB_USER: Database username (e.g., postgres)
• DB_PASSWORD: Database password (e.g., yourpassword)

Example .env file:

DB_HOST=localhost
DB_PORT=5432
DB_NAME=buildaquery
DB_USER=postgres
DB_PASSWORD=yourpassword

For Developers

Clone the repository and set up the development environment:

git clone https://github.com/yourusername/buildaquery.git
cd buildaquery

Install dependencies using Poetry:

poetry install

Activate the virtual environment:

poetry shell

Quick Start

Here's a simple example of creating a table, inserting data, querying it, and dropping the table. This example uses environment variables for database connection (see Environment Variables section above).

from dotenv import load_dotenv
import os
from buildaquery.execution.postgres import PostgresExecutor
from buildaquery.abstract_syntax_tree.models import (
    CreateStatementNode, TableNode, ColumnDefinitionNode,
    InsertStatementNode, ColumnNode, LiteralNode,
    SelectStatementNode, StarNode, DropStatementNode
)

# Load environment variables
load_dotenv()

# Build connection string from environment variables
db_host = os.getenv('DB_HOST')
db_port = os.getenv('DB_PORT')
db_name = os.getenv('DB_NAME')
db_user = os.getenv('DB_USER')
db_password = os.getenv('DB_PASSWORD')

connection_string = f"postgresql://{db_user}:{db_password}@{db_host}:{db_port}/{db_name}"

# Set up executor with your PostgreSQL connection
executor = PostgresExecutor(connection_info=connection_string)

# Define table
users_table = TableNode(name="users")

# Create table
create_stmt = CreateStatementNode(
    table=users_table,
    columns=[
        ColumnDefinitionNode(name="id", data_type="SERIAL", primary_key=True),
        ColumnDefinitionNode(name="name", data_type="TEXT", not_null=True),
        ColumnDefinitionNode(name="age", data_type="INTEGER")
    ]
)
executor.execute(create_stmt)

# Insert data
insert_stmt = InsertStatementNode(
    table=users_table,
    columns=[ColumnNode(name="name"), ColumnNode(name="age")],
    values=[LiteralNode(value="Alice"), LiteralNode(value=30)]
)
executor.execute(insert_stmt)

# Query data
select_stmt = SelectStatementNode(
    select_list=[StarNode()],  # SELECT *
    from_table=users_table
)
results = executor.execute(select_stmt)
print(results)  # [(1, 'Alice', 30)]

# Drop table
drop_stmt = DropStatementNode(table=users_table, if_exists=True)
executor.execute(drop_stmt)

For more examples, see the examples/ directory.

Development Setup

Prerequisites

• Python 3.12+
• Poetry (for dependency management)
• Docker (for running integration tests)

Setting Up the Environment

1. Clone the repository:

   git clone https://github.com/yourusername/buildaquery.git
   cd buildaquery
   

2. Install dependencies:

   poetry install
   

3. Activate the virtual environment:

   poetry shell
   

Running Tests

Unit Tests

Run unit tests for all modules:

poetry run pytest buildaquery/tests

Integration Tests

Integration tests require a PostgreSQL database. Start the test database using Docker:

docker-compose up -d

Then run integration tests:

poetry run pytest tests

All Tests

Run all tests (unit and integration):

poetry run all-tests

Running Examples

Execute the sample script:

poetry run python examples/sample_query.py

Project Structure

• buildaquery/abstract_syntax_tree/: Defines query nodes and AST models.
• buildaquery/traversal/: Base classes for AST traversal (Visitor/Transformer pattern).
• buildaquery/compiler/: Dialect-specific SQL generation (currently PostgreSQL).
• buildaquery/execution/: Database connection and execution logic.
• tests/: Exhaustive unit and integration tests.
• examples/: Practical demonstrations of the library.
• scripts/: Utility scripts for testing and maintenance.

Contributing

Contributions are welcome! Please see the contributing guidelines for more information.

License

This project is licensed under the MIT License - see the LICENSE.txt file for details.