pg_async is an unofficial PostreSQL database asynchronous client library written in modern C++ (std=c++11) on top of boost::asio library used for asynchronous network input-output.

Features

Asynchronous operations
Connection pooling
Database aliases
Standard container-compliant resultset interface
Execution of prepared statements
Query queuing
Multiple result sets for simple query mode
Data row extraction to tuples
Flexible datatype conversion
Compile-time statement parameter types binding and checking
Extensible datatypes input-output system
TCP or UNIX socket connection

Short usage overview

All classes are located in namespace tip::db::pg, if not specified other way.

Registering a connection

#include <tip/db/pg.hpp>
using namespace tip::db::pg;
db_service::add_connection("main=tcp://user:pass@the-database-server:5432[databasename]");
db_service::add_connection("logs=tcp://user:pass@the-database-server:5432[logs_db]");
db_service::run();

See Also: Connection string and database alias; tip::db::pg::db_service reference

Transactions

db_service::begin(
    "main"_db, // Database alias
    // Asynchronous callback, will be called as soon as a connection becomes
    // idle, and a new transaction will be started in it.
    [] (transaction_ptr tran)
    {
        // Run the queries here
        // A transaction MUST be explicitly commited or it will be rolled back
        tran->commit();
    },
    // Transaction error handler.
    [](db_error const& error)
    {
    }
);

See Also: Transactions; Connection string and database alias; Threads and thread safety; tip::db::pg::transaction for reference

Querying

#include <tip/db/pg.hpp>
query("main"_db, "select * from pg_catalog.pg_types").run_async(
[&](transaction_ptr t, resultset res, bool complete) {
    // Process the query results
},
[&](db_error const& err) {
    // Handle query error
});

See Also: Running queries for more information; Errors and exceptions; Callback types; Values input/output; tip::db::pg::query for reference

Processing query results

resultset res; // Passed to a callback from query
if (res) {
    for (auto row : res) { // Row iteration
        for (auto field : row) {
            std::string value = field.coalesce("default value");
        }
    }
}

See Also: Processing query results for more information; Values input/output; tip::db::pg::resultset for reference; tip::db::pg::resultset::row for reference; tip::db::pg::resultset::field for reference