Beginner Outlook Calendar Summary with OpenAI

A step-by-step demo that shows how to pull your Outlook calendar events for the week and ask GPT-4o to write a short summary.
Along the way you’ll practice basic data-transform nodes (Code, Filter, Aggregate) and see where to attach the required API credentials.

1️⃣ Manual Trigger — Run Workflow | Why | Lets you click “Execute” in the n8n editor so you can test each change. | | --- | --- |

2️⃣ Get Outlook Events — Get many events Node type: Microsoft Outlook → Event → Get All
Fields selected: subject, start
API setup (inside this node):
Click Credentials ▸ Microsoft Outlook OAuth2 API
If you haven’t connected before:
Choose “Microsoft Outlook OAuth2 API” → “Create New”.
Sign in and grant the Calendars.Read permission.
Save the credential (e.g., “Microsoft Outlook account”).
Output: A list of events with the raw ISO start time.

> Teaching moment: Outlook returns a full dateTime string. We’ll normalize it next so it’s easy to filter.

3️⃣ Normalize Dates — Convert to Date Format
// Code node contents return $input.all().map(item => { const startDateTime = new Date(item.json.start.dateTime); const formattedDate = startDateTime.toISOString().split('T')[0]; // YYYY-MM-DD return { json: { ...item.json, startDateFormatted: formattedDate } }; });

4️⃣ Filter the Events Down to This Week
After we’ve normalised the start date-time into a simple YYYY-MM-DD string, we drop in a Filter node.
Add one rule for every day you want to keep—for example 2025-08-07 or 2025-08-08. Rows that match any of those dates will continue through the workflow; everything else is quietly discarded.

Why we’re doing this: we only want to summarise tomorrow’s and the following day’s meetings, not the entire calendar.

5️⃣ Roll All Subjects Into a Single Item
Next comes an Aggregate node. Tell it to aggregate the subject field and choose the option “Only aggregated fields.”
The result is one clean item whose subject property is now a tidy list of every meeting title. It’s far easier (and cheaper) to pass one prompt to GPT than dozens of small ones.

6️⃣ Turn That List Into Plain Text
Insert a small Code node right after the aggregation:

return [{ json: { text: items .map(item => JSON.stringify(item.json)) .join('\n') } }];

Need a Hand? I’m always happy to chat automation, n8n, or Outlook API quirks.

Robert Breen – Automation Consultant & n8n Instructor 📧 robert@ynteractive.com | LinkedIn