Connection Management

/**
 * Creates a new PostgreSQL client instance
 * @param config - Optional configuration object
 * @returns New Client instance
 */
const Client = require('pg-native');

// Constructor pattern (recommended)
const client = new Client(config);

// Factory pattern (also supported - no 'new' required)
const client = Client(config);

interface ClientConfig {
  /** Custom type conversion parser (defaults to pg-types) */
  types?: TypeParser;
  /** Return results as arrays instead of objects */
  arrayMode?: boolean;
}

const Client = require('pg-native');

// Basic client
const client = new Client();

// Client with array mode enabled  
const arrayClient = new Client({ arrayMode: true });

// Client with custom type parsing
const customClient = new Client({ 
  types: customTypeParser,
  arrayMode: false 
});

/**
 * Connect to PostgreSQL server asynchronously
 * @param params - Optional connection string in libpq format
 * @param callback - Required callback function
 */
client.connect(params?: string, callback: (err: Error | null) => void): void;

const client = new Client();

// Connect using environment variables
client.connect(function(err) {
  if (err) throw err;
  console.log('Connected!');
});

// Connect with connection string
client.connect('postgresql://user:pass@localhost:5432/mydb', function(err) {
  if (err) throw err;
  console.log('Connected with URI!');
});

// Connect with key-value parameters
client.connect('host=localhost port=5432 dbname=test', function(err) {
  if (err) throw err;
  console.log('Connected with key-value params!');
});

/**
 * Connect to PostgreSQL server synchronously
 * @param params - Optional connection string in libpq format
 * @throws Error if connection fails
 */
client.connectSync(params?: string): void;

const client = new Client();

try {
  // Connect using environment variables
  client.connectSync();
  console.log('Connected synchronously!');
} catch (err) {
  console.error('Connection failed:', err.message);
}

try {
  // Connect with connection string
  client.connectSync('postgresql://user:pass@localhost:5432/mydb');
  console.log('Connected with URI!');
} catch (err) {
  console.error('Connection failed:', err.message);
}

/**
 * End the connection to PostgreSQL server
 * @param callback - Optional callback called when connection ends
 */
client.end(callback?: () => void): void;

// End connection with callback
client.end(function() {
  console.log('Connection ended');
});

// End connection without callback
client.end();

// Client extends EventEmitter
client.on('error', (error: Error) => void);
client.on('readyForQuery', () => void);

const client = new Client();

client.on('error', function(err) {
  console.error('Connection error:', err.message);
});

client.on('readyForQuery', function() {
  console.log('Client ready for queries');
});

client.connect(function(err) {
  if (err) throw err;
  // Connection successful
});