Send a message to a Channel in Teams via Graph - php

Question

I try to send a message to a specific channel in teams.
It works perfectly with 'https://developer.microsoft.com/de-de/graph/graph-explorer'.
For reciving the access token i do the following. This part works, because i can retrieve user information and other things with it.
$guzzle = new \GuzzleHttp\Client(['verify' => false]);
$tenantId = '<tenant_id>';
$clientId = '<client_id>';
$clientSecret = '<client_secret>';
$url = 'https://login.microsoftonline.com/' . $tenantId . '/oauth2/token?api-version=1.0';
$token = json_decode($guzzle->post($url, [
'form_params' => [
'client_id' => $clientId,
'client_secret' => $clientSecret,
'resource' => 'https://graph.microsoft.com/',
'grant_type' => 'client_credentials',
],
'verify' => false
])->getBody()->getContents());
$accessToken = $token->access_token;
This part now is the one that produces the error
$graph = new Graph();
$graph->setAccessToken($accessToken);
$url = '/teams/<team_id>/channels/<channel_id>/messages';
$queryParams = [
'body' => [
'content' => 'foo'
]
];
$info = $graph->setApiVersion("beta")->createRequest("POST", $url)
->addHeaders(array("Content-Type" => "application/json"))
->attachBody($queryParams)
->setReturnType(BetaModel\User::class)
->execute();
echo '<pre>';
print_r($info);
This produces the following error
{
"error": {
"code": "UnknownError",
"message": "",
"innerError": {
"date": "2020-11-11T10:14:03",
"request-id": "<request_id>",
"client-request-id": "<client_request_id>"
}
}
}
The teams id and the channel id are correct, i can retrieve them by using
/users/<user_id>/joinedTeams
and
/teams/<teams_id>/channels
and as mentioned earlier, it works in the graph explorer page.
I know that i somehow need to send the message in an user context, but i can't make it work, and i can't find useful informations, so i am pleased for any. Thanks in advance!

Answer 1

This api call currently does not support application permissions, so you cannot use the client credential flow to obtain a token. You need to grant delegated permissions to the application, and then use the auth code flow to obtain the token. see:here.