As part of the upgrade of the Microsoft Graph .NET Client Library from version 4 to version 5, my work mate and I have adapted the usage of the GraphServiceClient methods in context of teams channel notification subscription creation according to the official documentation. Unfortunately it didn’t work… and it cost us a few hours and above all nerves… In the meantime we finally found a solution which I gladly share with you to save you the same headache.
With Microsoft Graph .NET Client Library v4 the code looked as follows.
var subscription = new Subscription
{
ChangeType = "created",
NotificationUrl = notificationUrl,
Resource = $"teams/{space.TeamsId}/channels/{space.GeneralChannelId}/messages",
ExpirationDateTime = expirationDateTime, // max 2h!
ClientState = space.SubscriptionSecret,
LatestSupportedTlsVersion = "v1_2"
};
var response = await _graphClient
.Subscriptions
.Request(new[] { new QueryOption("model", "B") })
.AddAsync(subscription);
According to the docs (see here), the updated code with Microsoft Graph .NET Client Library v5 would look as follows.
var subscription = new Subscription
{
ChangeType = "created",
NotificationUrl = notificationUrl,
Resource = $"teams/{space.TeamsId}/channels/{space.GeneralChannelId}/messages?model=B",
ExpirationDateTime = expirationDateTime, // max 2h!
ClientState = space.SubscriptionSecret,
LatestSupportedTlsVersion = "v1_2"
};
var response = await _graphClient
.Subscriptions
.PostAsync(subscription);
However as already mentioned above, this code did/does not work. It fails with the following exception message.
Fails with: [Status Code: BadRequest; Reason: Query parameter 'model' is not supported for this resource type.
After a lot of debugging, analysis and research we finally could make it work!
Working version inspired by https://stackoverflow.com/a/77451153/2796003 looks as follows
var subscription = new Subscription
{
ChangeType = "created",
NotificationUrl = notificationUrl,
Resource = $"teams/{space.TeamsId}/channels/{space.GeneralChannelId}/messages",
ExpirationDateTime = expirationDateTime, // max 2h!
ClientState = space.SubscriptionSecret,
LatestSupportedTlsVersion = "v1_2"
};
var requestInformation = _graphClient
.Subscriptions
.ToPostRequestInformation(subscription);
requestInformation.QueryParameters["model"] = new[] { "B" };
requestInformation.UrlTemplate += "{?model}";
var response =
await _graphClient.RequestAdapter.SendAsync(
requestInformation,
Subscription.CreateFromDiscriminatorValue
);
Seems to be a known issue that query parameters do not work as expected in POST requests using Microsoft Graph .NET Client Library v5 based on https://github.com/microsoftgraph/msgraph-sdk-dotnet/issues/1975.
blog.rufer.be 
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