sqlgen/docs/postgres.md

sqlgen::postgres

The sqlgen::postgres module provides a type-safe and efficient interface for interacting with PostgreSQL databases. It implements the core database operations through a connection-based API with support for prepared statements, transactions, and efficient data iteration.

Usage

Basic Connection

Create a connection to a PostgreSQL database using credentials:

// Create credentials for the database connection
const auto creds = sqlgen::postgres::Credentials{
                        .user = "myuser",
                        .password = "mypassword",
                        .host = "localhost",
                        .dbname = "mydatabase",
                        .port = 5432  // Optional, defaults to 5432
                    };

// Connect to the database
const auto conn = sqlgen::postgres::connect(creds);

The connection is wrapped in a sqlgen::Result<Ref<Connection>> for error handling:

// Handle connection errors
const auto conn = sqlgen::postgres::connect(creds);
if (!conn) {
    // Handle error...
    return;
}

using namespace sqlgen;
using namespace sqlgen::literals;

const auto query = sqlgen::read<std::vector<Person>> |
                   where("age"_c < 18 and "first_name"_c != "Hugo");

// Use the connection
const auto minors = query(conn);

Notes

• The module provides a type-safe interface for PostgreSQL operations
• All operations return sqlgen::Result<T> for error handling
• The COPY operator is used under-the-hood for efficient data insertion
• The iterator interface supports batch processing of results
• SQL generation adapts to PostgreSQL's dialect
• The module supports:
  • Connection management with credentials
  • Transactions
  • Prepared statements
  • Efficient batch operations
  • Type-safe SQL generation
  • Error handling through Result<T>
  • Resource management through Ref<T>
  • Customizable connection parameters (host, port, database name, etc.)