Add support for named parameters (#16)

* Include library node-postgres-named
https://github.com/bwestergard/node-postgres-named

* eslint fix + format

* Simplify credits

* Remove lodash dependency

* Add tests
https://github.com/bwestergard/node-postgres-named/blob/master/test/test.js

* Simplification, removed libraries, and integration

Author: Alkarex

README.md

@@ -37,7 +37,7 @@ SELECT * FROM table WHERE id = '{{{ msg.id }}}';
 
 As an alternative to using the query template above, this node also accepts an SQL query via the `msg.query` parameter.
 
-### Parameterized query
+### Parameterized query (numeric)
 
 Parameters for parameterized queries can be passed as a parameter array `msg.params`:
 
@@ -51,6 +51,24 @@ msg.params = [ msg.id ];
 SELECT * FROM table WHERE id = $1;
 ```
 
+### Named parameterized query
+
+As an alternative to numeric parameters,
+named parameters for parameterized queries can be passed as a parameter array `msg.queryParameters`:
+
+```js
+// In a function, provide parameters for the named parameterized query
+msg.queryParameters.id = msg.id;
+```
+
+```sql
+-- In this node, use a named parameterized query
+SELECT * FROM table WHERE id = $id;
+```
+
+_Note_: named parameters are not natively supported by PostgreSQL, and this library just emulates them,
+so this is less robust than numeric parameters.
+
 ### Dynamic PostgreSQL connection parameters
 
 If the information about which database server to connect and how needs to be dynamic,

locales/en-US/postgresql.html

@@ -42,12 +42,32 @@ <h4>Parameterized queries</h4>
 SELECT * FROM table WHERE id = $1
 </pre>
 
+<h4>Parameterized queries</h4>
+<p>
+	As an alternative to numeric parameters,
+	named parameters for parameterized queries can be passed as a parameter arrayy <code>msg.queryParameters</code>:
+</p>
+<pre>
+// In a function, provide parameters for the named parameterized query
+msg.queryParameters.id = msg.id;
+</pre>
+
+<pre>
+-- In this node, use a named parameterized query
+SELECT * FROM table WHERE id = $id;
+</pre>
+
+<p>
+	<em>Note</em>: named parameters are not natively supported by PostgreSQL, and this library just emulates them,
+	so this is less robust than numeric parameters.
+</p>
+
 	<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
@@ -85,7 +105,7 @@ <h3>Backpressure</h3>
 		and a truthy <code>node.tickProvider</code> for upstream nodes.
 		Likewise, this node detects upstream nodes using the same back-pressure convention, and automatically sends ticks.
 	</p>
-	
+
 	<h3>Sequences for split results</h3>
 	<p>
 		When the <em>Split results</em> option is enabled (streaming), the messages contain some information following the conventions

node-postgres-named.js

@@ -0,0 +1,33 @@
+'use strict';
+
+/**
+ * Rewritten subset of the library https://github.com/bwestergard/node-postgres-named/blob/master/main.js
+ * https://github.com/ksteckert/node-postgres-named/tree/patch-1
+ */
+
+const tokenPattern = /(?<=\$)[a-zA-Z]([a-zA-Z0-9_]*)\b/g;
+
+function numericFromNamed(sql, parameters) {
+	const fillableTokens = new Set(Object.keys(parameters));
+	const matchedTokens = new Set(sql.match(tokenPattern));
+
+	const unmatchedTokens = Array.from(matchedTokens).filter((token) => !fillableTokens.has(token));
+	if (unmatchedTokens.length > 0) {
+		throw new Error('Missing Parameters: ' + unmatchedTokens.join(', '));
+	}
+
+	const fillTokens = Array.from(matchedTokens).filter((token) => fillableTokens.has(token)).sort();
+	const fillValues = fillTokens.map((token) => parameters[token]);
+
+	const interpolatedSql = fillTokens.reduce((partiallyInterpolated, token, index) => {
+		const replaceAllPattern = new RegExp('\\$' + fillTokens[index] + '\\b', 'g');
+		return partiallyInterpolated.replace(replaceAllPattern, '$' + (index + 1)); // PostgreSQL parameters are 1-indexed
+	}, sql);
+
+	return {
+		text: interpolatedSql,
+		values: fillValues,
+	};
+}
+
+module.exports.convert = numericFromNamed;