🎨 Extract postgres functionality (#737)

* 🎉 executeQuery function extracted

* 🚧 add prettierrc to gitignore

* 🚧 insert function extracted

* ⚡ extract update function

* 💡 fix function docs

* 💡 add in code documentation

* 🎨 fix format

* 🎨 fix format

packages/nodes-base/nodes/Postgres/Postgres.node.functions.ts

@@ -0,0 +1,129 @@
+import { IDataObject, INodeExecutionData } from 'n8n-workflow';
+import pgPromise = require('pg-promise');
+import pg = require('pg-promise/typescript/pg-subset');
+
+/**
+ * Returns of copy of the items which only contains the json data and
+ * of that only the define properties
+ *
+ * @param {INodeExecutionData[]} items The items to copy
+ * @param {string[]} properties The properties it should include
+ * @returns
+ */
+function getItemCopy(items: INodeExecutionData[], properties: string[]): IDataObject[] {
+	// Prepare the data to insert and copy it to be returned
+	let newItem: IDataObject;
+	return items.map(item => {
+		newItem = {};
+		for (const property of properties) {
+			if (item.json[property] === undefined) {
+				newItem[property] = null;
+			} else {
+				newItem[property] = JSON.parse(JSON.stringify(item.json[property]));
+			}
+		}
+		return newItem;
+	});
+}
+
+/**
+ * Executes the given SQL query on the database.
+ *
+ * @param {Function} getNodeParam The getter for the Node's parameters
+ * @param {pgPromise.IMain<{}, pg.IClient>} pgp The pgPromise instance
+ * @param {pgPromise.IDatabase<{}, pg.IClient>} db The pgPromise database connection
+ * @param {input[]} input The Node's input data
+ * @returns Promise<Array<object>>
+ */
+export function pgQuery(
+	getNodeParam: Function,
+	pgp: pgPromise.IMain<{}, pg.IClient>,
+	db: pgPromise.IDatabase<{}, pg.IClient>,
+	input: INodeExecutionData[],
+): Promise<Array<object>> {
+	const queries: string[] = [];
+	for (let i = 0; i < input.length; i++) {
+		queries.push(getNodeParam('query', i) as string);
+	}
+
+	return db.any(pgp.helpers.concat(queries));
+}
+
+/**
+ * Inserts the given items into the database.
+ *
+ * @param {Function} getNodeParam The getter for the Node's parameters
+ * @param {pgPromise.IMain<{}, pg.IClient>} pgp The pgPromise instance
+ * @param {pgPromise.IDatabase<{}, pg.IClient>} db The pgPromise database connection
+ * @param {INodeExecutionData[]} items The items to be inserted
+ * @returns Promise<Array<IDataObject>>
+ */
+export async function pgInsert(
+	getNodeParam: Function,
+	pgp: pgPromise.IMain<{}, pg.IClient>,
+	db: pgPromise.IDatabase<{}, pg.IClient>,
+	items: INodeExecutionData[],
+): Promise<Array<IDataObject[]>> {
+	const table = getNodeParam('table', 0) as string;
+	const schema = getNodeParam('schema', 0) as string;
+	let returnFields = (getNodeParam('returnFields', 0) as string).split(',') as string[];
+	const columnString = getNodeParam('columns', 0) as string;
+	const columns = columnString.split(',').map(column => column.trim());
+
+	const cs = new pgp.helpers.ColumnSet(columns);
+
+	const te = new pgp.helpers.TableName({ table, schema });
+
+	// Prepare the data to insert and copy it to be returned
+	const insertItems = getItemCopy(items, columns);
+
+	// Generate the multi-row insert query and return the id of new row
+	returnFields = returnFields.map(value => value.trim()).filter(value => !!value);
+	const query =
+		pgp.helpers.insert(insertItems, cs, te) +
+		(returnFields.length ? ` RETURNING ${returnFields.join(',')}` : '');
+
+	// Executing the query to insert the data
+	const insertData = await db.manyOrNone(query);
+
+	return [insertData, insertItems];
+}
+
+/**
+ * Updates the given items in the database.
+ *
+ * @param {Function} getNodeParam The getter for the Node's parameters
+ * @param {pgPromise.IMain<{}, pg.IClient>} pgp The pgPromise instance
+ * @param {pgPromise.IDatabase<{}, pg.IClient>} db The pgPromise database connection
+ * @param {INodeExecutionData[]} items The items to be updated
+ * @returns Promise<Array<IDataObject>>
+ */
+export async function pgUpdate(
+	getNodeParam: Function,
+	pgp: pgPromise.IMain<{}, pg.IClient>,
+	db: pgPromise.IDatabase<{}, pg.IClient>,
+	items: INodeExecutionData[],
+): Promise<Array<IDataObject>> {
+	const table = getNodeParam('table', 0) as string;
+	const updateKey = getNodeParam('updateKey', 0) as string;
+	const columnString = getNodeParam('columns', 0) as string;
+
+	const columns = columnString.split(',').map(column => column.trim());
+
+	// Make sure that the updateKey does also get queried
+	if (!columns.includes(updateKey)) {
+		columns.unshift(updateKey);
+	}
+
+	// Prepare the data to update and copy it to be returned
+	const updateItems = getItemCopy(items, columns);
+
+	// Generate the multi-row update query
+	const query =
+		pgp.helpers.update(updateItems, columns, table) + ' WHERE v.' + updateKey + ' = t.' + updateKey;
+
+	// Executing the query to update the data
+	await db.none(query);
+
+	return updateItems;
+}