Step 4.16: Add 'addMessage()' method to api

server/imports/methods/methods.ts

@@ -0,0 +1,18 @@
+import {Meteor} from 'meteor/meteor';
+import {Chats} from "../../../both/collections/chats.collection";
+import {Messages} from "../../../both/collections/messages.collection";
+
+Meteor.methods({
+  addMessage(chatId: string, content: string): void {
+    const chatExists = !!Chats.collection.find(chatId).count();
+
+    if (!chatExists) throw new Meteor.Error('chat-not-exists',
+      'Chat doesn\'t exist');
+
+    Messages.collection.insert({
+      chatId: chatId,
+      content: content,
+      createdAt: new Date()
+    });
+  }
+});