Some changes

server/src/models/appointment.js

@@ -0,0 +1,43 @@
+import mongoose from 'mongoose';
+import timestamps from 'mongoose-timestamp';
+import { composeWithMongoose } from 'graphql-compose-mongoose';
+
+export const AppointmentSchema = new mongoose.Schema(
+    {
+        user: {
+            type: mongoose.Schema.Types.ObjectId,
+            ref: 'User',
+            required: true,
+        },
+
+        title: {
+            type: String,
+            required: true,
+        },
+
+        description: {
+            type: String,
+            required: true,
+        },
+
+        timeStart: {
+            type: Date,
+            required: true,
+        },
+
+        timeEnd: {
+            type: Date,
+            required: true,
+        },
+    },
+    {
+        collection: 'appointment',
+    }
+);
+
+AppointmentSchema.plugin(timestamps);
+
+AppointmentSchema.index({ createdAt: 1, updatedAt: 1 });
+
+export const Appointment = mongoose.model('Appointment', AppointmentSchema);
+export const AppointmentTC = composeWithMongoose(Appointment);