feat(MongoDb Node): Add Aggregate Operation

* MongoDB Aggregate Option

* ⚡ small improvements to UI

Co-authored-by: Michael Kret <michael.k@radency.com>

packages/nodes-base/nodes/MongoDb/MongoDb.node.ts

@@ -7,6 +7,7 @@ import {
 	INodeExecutionData,
 	INodeType,
 	INodeTypeDescription,
+	JsonObject,
 	NodeOperationError
 } from 'n8n-workflow';
 
@@ -46,7 +47,33 @@ export class MongoDb implements INodeType {
 		const items = this.getInputData();
 		const operation = this.getNodeParameter('operation', 0) as string;
 
-		if (operation === 'delete') {
+		if (operation === 'aggregate') {
+			// ----------------------------------
+			//         aggregate
+			// ----------------------------------
+
+			try {
+				const queryParameter = JSON.parse(this.getNodeParameter('query', 0) as string);
+
+				if (queryParameter._id && typeof queryParameter._id === 'string') {
+					queryParameter._id = new ObjectID(queryParameter._id);
+				}
+
+				const query = mdb
+					.collection(this.getNodeParameter('collection', 0) as string)
+					.aggregate(queryParameter);
+
+				const queryResult = await query.toArray();
+
+				returnItems = this.helpers.returnJsonArray(queryResult as IDataObject[]);
+			} catch (error) {
+				if (this.continueOnFail()) {
+					returnItems = this.helpers.returnJsonArray({ error: (error as JsonObject).message } );
+				} else {
+					throw error;
+				}
+			}
+		} else if (operation === 'delete') {
 			// ----------------------------------
 			//         delete
 			// ----------------------------------
@@ -59,7 +86,7 @@ export class MongoDb implements INodeType {
 				returnItems = this.helpers.returnJsonArray([{ deletedCount }]);
 			} catch (error) {
 				if (this.continueOnFail()) {
-					returnItems = this.helpers.returnJsonArray({ error: error.message });
+					returnItems = this.helpers.returnJsonArray({ error: (error as JsonObject).message });
 				} else {
 					throw error;
 				}
@@ -99,7 +126,7 @@ export class MongoDb implements INodeType {
 				returnItems = this.helpers.returnJsonArray(queryResult as IDataObject[]);
 			} catch (error) {
 				if (this.continueOnFail()) {
-					returnItems = this.helpers.returnJsonArray({ error: error.message } );
+					returnItems = this.helpers.returnJsonArray({ error: (error as JsonObject).message } );
 				} else {
 					throw error;
 				}
@@ -137,7 +164,7 @@ export class MongoDb implements INodeType {
 				}
 			} catch (error) {
 				if (this.continueOnFail()) {
-					returnItems = this.helpers.returnJsonArray({ error: error.message });
+					returnItems = this.helpers.returnJsonArray({ error: (error as JsonObject).message });
 				} else {
 					throw error;
 				}
@@ -188,7 +215,7 @@ export class MongoDb implements INodeType {
 						.updateOne(filter, { $set: item }, updateOptions);
 				} catch (error) {
 					if (this.continueOnFail()) {
-						item.json = { error: error.message };
+						item.json = { error: (error as JsonObject).message };
 						continue;
 					}
 					throw error;

packages/nodes-base/nodes/MongoDb/mongo.node.options.ts

@@ -29,6 +29,11 @@ export const nodeDescription: INodeTypeDescription = {
 			name: 'operation',
 			type: 'options',
 			options: [
+				{
+					name: 'Aggregate',
+					value: 'aggregate',
+					description: 'Aggregate documents.',
+				},
 				{
 					name: 'Delete',
 					value: 'delete',
@@ -63,6 +68,30 @@ export const nodeDescription: INodeTypeDescription = {
 			description: 'MongoDB Collection',
 		},
 
+		// ----------------------------------
+		//         aggregate
+		// ----------------------------------
+		{
+			displayName: 'Query',
+			name: 'query',
+			type: 'json',
+			typeOptions: {
+				alwaysOpenEditWindow: true,
+			},
+			displayOptions: {
+				show: {
+					operation: [
+						'aggregate',
+					],
+				},
+			},
+			default: '',
+			placeholder: `[{ "$match": { "$gt": "1950-01-01" }, ... }]`,
+			hint: 'Learn more about aggregation pipeline <a href="https://docs.mongodb.com/manual/core/aggregation-pipeline/">here</a>',
+			required: true,
+			description: 'MongoDB aggregation pipeline query in JSON format',
+		},
+
 		// ----------------------------------
 		//         delete
 		// ----------------------------------
@@ -149,6 +178,7 @@ export const nodeDescription: INodeTypeDescription = {
 			required: true,
 			description: 'MongoDB Find query.',
 		},
+
 		// ----------------------------------
 		//         insert
 		// ----------------------------------