Dynamic PostgreSQL client config (#9)

* Dynamic PostgreSQL client config

* Minor readme

* Minor documentation

* Additional notes

Author: Alkarex

README.md

@@ -47,6 +47,32 @@ msg.params = [ msg.id ];
 SELECT * FROM table WHERE id = $1;
 ```
 
+### Dynamic PostgreSQL connection parameters
+
+If the information about which database server to connect and how needs to be dynamic,
+it is possible to pass a [custom client configuration](https://node-postgres.com/api/client) in the message:
+
+```js
+msg.pgConfig = {
+  user?: string, // default process.env.PGUSER || process.env.USER
+  password?: string, //or function, default process.env.PGPASSWORD
+  host?: string, // default process.env.PGHOST
+  database?: string, // default process.env.PGDATABASE || process.env.USER
+  port?: number, // default process.env.PGPORT
+  connectionString?: string, // e.g. postgres://user:password@host:5432/database
+  ssl?: any, // passed directly to node.TLSSocket, supports all tls.connect options
+  types?: any, // custom type parsers
+  statement_timeout?: number, // number of milliseconds before a statement in query will time out, default is no timeout
+  query_timeout?: number, // number of milliseconds before a query call will timeout, default is no timeout
+  application_name?: string, // The name of the application that created this Client instance
+  connectionTimeoutMillis?: number, // number of milliseconds to wait for connection, default is no timeout
+  idle_in_transaction_session_timeout?: number, // number of milliseconds before terminating any session with an open idle transaction, default is no timeout
+};
+```
+
+However, this does not use a [connection pool](https://node-postgres.com/features/pooling), and is therefore less efficient.
+It is therefore recommended in most cases not to use `msg.pgConfig` at all and instead stick to the built-in configuration node.
+
 ## Installation
 
 ### Using the Node-RED Editor

locales/en-US/postgresql.html

@@ -39,6 +39,34 @@ <h4>Parameterized queries</h4>
 SELECT * FROM table WHERE id = $1
 </pre>
 
+	<h4>Dynamic PostgreSQL connection parameters</h4>
+	<p>
+		If the information about which database server to connect and how needs to be dynamic,
+		it is possible to pass a <a href="https://node-postgres.com/api/client">custom client configuration</a> in the message:
+	</p>
+		
+<pre>
+msg.pgConfig = {
+  user?: string, // default process.env.PGUSER || process.env.USER
+  password?: string, //or function, default process.env.PGPASSWORD
+  host?: string, // default process.env.PGHOST
+  database?: string, // default process.env.PGDATABASE || process.env.USER
+  port?: number, // default process.env.PGPORT
+  connectionString?: string, // e.g. postgres://user:password@host:5432/database
+  ssl?: any, // passed directly to node.TLSSocket, supports all tls.connect options
+  types?: any, // custom type parsers
+  statement_timeout?: number, // number of milliseconds before a statement in query will time out, default is no timeout
+  query_timeout?: number, // number of milliseconds before a query call will timeout, default is no timeout
+  application_name?: string, // The name of the application that created this Client instance
+  connectionTimeoutMillis?: number, // number of milliseconds to wait for connection, default is no timeout
+  idle_in_transaction_session_timeout?: number, // number of milliseconds before terminating any session with an open idle transaction, default is no timeout
+};
+</pre>
+	<p>
+		However, this does not use a <a href="https://node-postgres.com/features/pooling">connection pool</a>, and is therefore less efficient.
+		It is therefore recommended in most cases not to use `msg.pgConfig` at all and instead stick to the built-in configuration node.
+	</p>
+
 	<h3>Backpressure</h3>
 	<p>
 		This node supports <em>backpressure</em> / <em>flow control</em>:

postgresql.js

@@ -29,7 +29,7 @@ function findInputNodeId(toNode, filter = null) {
 
 module.exports = function (RED) {
 	const Mustache = require('mustache');
-	const Pool = require('pg').Pool;
+	const { Client, Pool } = require('pg');
 	const Cursor = require('pg-cursor');
 
 	function getField(node, kind, value) {
@@ -129,13 +129,17 @@ module.exports = function (RED) {
 
 				let client = null;
 
-				const handleDone = () => {
+				const handleDone = async () => {
 					if (cursor) {
 						cursor.close();
 						cursor = null;
 					}
 					if (client) {
-						client.release(true);
+						if (client.release) {
+							client.release(true);
+						} else if (client.end) {
+							await client.end();
+						}
 						client = null;
 					}
 					getNextRows = null;
@@ -159,7 +163,12 @@ module.exports = function (RED) {
 				downstreamReady = true;
 
 				try {
-					client = await node.config.pgPool.connect();
+					if (msg.pgConfig) {
+						client = new Client(msg.pgConfig);
+						await client.connect();
+					} else {
+						client = await node.config.pgPool.connect();
+					}
 
 					if (node.split) {
 						let partsIndex = 0;