Office 365 Calendar Rest API: Meeting Vs. Appointment
<p>Good Day,</p>

<p>For the sake of only adding verbose information if needed, I will describe the problem I am having, then provide examples if required for finding the answer.</p>

<p>In Outlook, I can create an appointment which seems to just to be a meeting where I am the organizer and the only attendee with no invites sent.</p>

<p>When I create a calendar entry in Outlook as an appointment (no invites), and then edit it in outlook, the "To:" field is not displayed, and I can click on Invite Attendees.</p>

<p>In Outlook, I can also create a new meeting, which seems to be the same as a appointment, but with attendees other then myself that get sent invites as part of the process.</p>

<p>On this page: <a href="https://msdn.microsoft.com/en-us/office/office365/api/calendar-rest-operations" rel="nofollow">https://msdn.microsoft.com/en-us/office/office365/api/calendar-rest-operations</a> it states that "Event operations An event represents an appointment or meeting on the user's calendar. An event can be a series master (for recurring events), an occurrence, a single instance, or an exception."</p>

<p>If I create both a meeting and an appointment in my outlook client, then request them with the API and compare the properties of the event, I can not find a functional difference between them. They both have me as organizer, and me as an attendee, they both seem to have the same event types, and other properties.</p>

<p>If I create a new event with the API, and try to leave "Attendees" null, it will fail to create with "bad request". if I put myself as both organizer and attendee (or just Attendee), it creates the event, but shows up as a meeting in my outlook with "no responses".</p>

<p>I can not figure out the combination of settings to use the API to create an event that appears as an appointment in outlook instead of a meeting.</p>

<p>Is there a property or setting I need to be sending in a certain way when using the rest api to create an event without any attendees/invites?</p>

<p>Thanks!</p>

<p>Steve</p>

<p><strong>Answer:</strong></p>

<p>Thanks to Jeffrey Chen I was able to find the problem in the post data I was sending.</p>

<p>I had created a DTO for a CalendarEvent with a property for "Attendees" as a List, but I did not initialize this list.</p>

<p>If I serialized to JSON with no Attendees, this property became null instead of an empty array [].</p>

<p>Turns out the attendees property can be left out entirely, but if it is included it must either be an empty array or contain actual attendees, null causes bad request.</p>

<p>Thanks!</p>