⚡ Add support for custom rules when checking emails. (#899)

* Add support for custom rules when checking emails.

* Add support for custom rules when checking emails.

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

@@ -30,7 +30,8 @@ export class EmailReadImap implements INodeType {
 			color: '#44AA22',
 		},
 		inputs: [],
-		outputs: ['main'],
+		outputs: ['main', 'main'],
+		outputNames: ['data', 'error'],
 		credentials: [
 			{
 				name: 'imap',
@@ -130,6 +131,27 @@ export class EmailReadImap implements INodeType {
 				},
 				description: 'Prefix for name of the binary property to which to<br />write the attachments. An index starting with 0 will be added.<br />So if name is "attachment_" the first attachment is saved to "attachment_0"',
 			},
+			{
+				displayName: 'Use custom email config',
+				name: 'useCustomEmailConfig',
+				type: 'boolean',
+				default: false,
+				description: 'If custom email rules should be used.',
+			},
+			{
+				displayName: 'Custom email rules',
+				name: 'customEmailConfig',
+				type: 'string',
+				default: "['UNSEEN']",
+				displayOptions: {
+					show: {
+						useCustomEmailConfig: [
+							true
+						],
+					},
+				},
+				description: 'Custom email fetching rules. See <a href="https://github.com/mscdex/node-imap">node-imap</a>\'s search function for more details'
+			},
 			{
 				displayName: 'Options',
 				name: 'options',
@@ -177,7 +199,11 @@ export class EmailReadImap implements INodeType {
 				return '';
 			}
 
-			return await connection.getPartData(message, textParts[0]);
+			try{
+				return await connection.getPartData(message, textParts[0]);
+			} catch {
+				return '';
+			}
 		};
 
 
@@ -211,10 +237,20 @@ export class EmailReadImap implements INodeType {
 		// Returns all the new unseen messages
 		const getNewEmails = async (connection: ImapSimple): Promise<INodeExecutionData[]> => {
 			const format = this.getNodeParameter('format', 0) as string;
-			const searchCriteria = [
+
+			let searchCriteria = [
 				'UNSEEN'
 			];
-
+			const useCustomEmailConfig = this.getNodeParameter('useCustomEmailConfig') as boolean;
+			if (useCustomEmailConfig) {
+				const customEmailConfig = this.getNodeParameter('customEmailConfig') as string;
+				try {
+					searchCriteria = eval(customEmailConfig);
+				} catch (err) {
+					throw new Error(`Parsing of ${customEmailConfig}\nfailed with error ${err}`);
+				}
+			}
+			
 			let fetchOptions = {};
 
 			if (format === 'simple' || format === 'raw') {
@@ -334,6 +370,19 @@ export class EmailReadImap implements INodeType {
 
 
 		let connection: ImapSimple;
+		let empty: INodeExecutionData[] = [];
+		let errToJson = (err: Error) => {
+			return {
+				json:
+				{
+					message: err.message,
+					stack: err.stack
+				}
+			};
+		}
+		let emitError = (err: Error) => {
+			this.emit([empty, [errToJson(err)]]);
+		}
 
 		const config: ImapSimpleOptions = {
 			imap: {
@@ -345,10 +394,14 @@ export class EmailReadImap implements INodeType {
 				authTimeout: 3000
 			},
 			onmail: async () => {
-				const returnData = await getNewEmails(connection);
+				try{
+					const returnData = await getNewEmails(connection);
 
-				if (returnData.length) {
-					this.emit([returnData]);
+					if (returnData.length) {
+						this.emit([returnData, empty]);
+					}
+				}catch(e) {
+					emitError(e);
 				}
 			},
 		};
@@ -361,9 +414,12 @@ export class EmailReadImap implements INodeType {
 
 		// Connect to the IMAP server and open the mailbox
 		// that we get informed whenever a new email arrives
-		connection = await imapConnect(config);
-		await connection.openBox(mailbox);
-
+		try {
+			connection = await imapConnect(config);
+			await connection.openBox(mailbox);
+		} catch (e) {
+			emitError(e);
+		}
 
 		// When workflow and so node gets set to inactive close the connectoin
 		async function closeFunction() {