Add database utilities file.

Intended to contain reusable functions.

lib/www/server/lib/db/utils.js

@@ -0,0 +1,28 @@
+/** @file utils.js Database utility functions
+ */
+
+
+/** Project a query
+ *
+ * @a rows are the tuples to operate on
+ * @a columns are the attributes to extract
+ *
+ * @return {Array} of projected tuples
+ */
+function project (rows, columns) {
+	if (columns) {
+		const tokens = Array.isArray(columns)
+			? columns
+			: columns.split(/\s*[,;:\s]\s*/).filter(e => e.length);
+		const project = tokens.map(i => i.replace(/^([^.]+)\..*$/, "$1"));
+		return rows.map( r =>
+			Object.fromEntries(Object.entries(r).filter(entry => project.includes(entry[0])))
+		);
+	} else {
+		return rows;
+	}
+}
+
+module.exports = {
+	project
+};