If you’re working with Microsoft Graph calendars, especially shared mailboxes, you’ve probably come across these two endpoints:

• /calendar/calendarView

• /calendar/events

At first glance, they look like they do the same thing.

But in reality… they don’t — and choosing the wrong one can break your calendar logic 😅

Let’s break this down in a simple, visual, and practical way.

🤔 The Big Question

“I just want to fetch calendar events — which API should I use?”

Answer:

👉 It depends on what kind of calendar experience you’re building.

🧩 Understanding the Core Difference

🟢 calendarView → “Show me what’s on the calendar”

🔵 events → “Show me event records”

That’s it.

1️⃣ Using /calendar/calendarView

const response = await client
  .api(`/users/${sharedMailboxUPN}/calendar/calendarView`)
  .query({
    startDateTime,
    endDateTime,
  })
  .filter("isCancelled eq false")
  .orderby("start/dateTime")
  .top(500)
  .get();

🧠 What it does

• Returns events that occur within a specific time range

• Expands recurring events into individual occurrences

• Behaves exactly like Outlook Calendar

Think of this as:

“Show me what actually appears on the calendar between these dates.”

✅ Why this is powerful

• ✔ Handles recurring meetings correctly

• ✔ Only shows events inside your date range

• ✔ Perfect for day / week / month views

• ✔ Ideal for shared mailboxes & room calendars

📌 Real-world example

If a meeting repeats every day, you’ll get:

• Monday meeting

• Tuesday meeting

• Wednesday meeting
  
  …each as a separate event

✨ Just like Outlook.

2️⃣ Using /calendar/events

const response = await client
  .api(`/users/${sharedMailboxUPN}/calendar/events`)
  .filter(`end/dateTime ge '${startDateTime}'`)
  .orderby("start/dateTime")
  .top(500)
  .get();

🧠 What it does

• Returns event definitions

• Does NOT expand recurring events

• Ignores real calendar boundaries

Think of this as:

“Show me the event objects stored in the mailbox.”

⚠️ Why this can be dangerous

• ❌ Recurring meetings appear only once

• ❌ You don’t get individual occurrences

• ❌ Filtering by date gives misleading results

• ❌ Not suitable for calendar UI

📌 Real-world problem

A meeting repeats daily for 1 year.

Using /events:

• You get one event

Using /calendarView:

• You get each daily meeting

Big difference 🚨

🆚 Side-by-Side Comparison

🎯 When Should You Use What?

✅ Use calendarView if:

• You are building a calendar UI

• You need correct recurring meetings

• You are working with shared mailboxes

• You care about date & time accuracy

👉 This is the correct choice for 90% of calendar apps

✅ Use events only if:

• You want to update or delete events

• You need series-level metadata

• You are building admin or maintenance tools

👉 Not recommended for displaying calendars.

🧠 Pro Tip: Timezone Matters

Always set timezone explicitly when using calendarView:

.headers({
  Prefer: 'outlook.timezone="Asia/Kolkata"'
})

This avoids:

• ❌ Events shifting time

• ❌ Midnight surprises

• ❌ “Why is this meeting at 3 AM?” bugs 😄

✅ Final Recommendation

If your question is:

“Which API should I use to show calendar events?”

Answer:

🟢 Use /calendar/calendarView

It’s accurate, reliable, and behaves exactly like Outlook.