Microsoft Graph - Teams API 在 Graph Explorer 上工作，但不能通过代码

Question

I have a requirement to automatically post a message on a Teams channel and mention the channel. Unfortunately via MS Flow, the option to mention an entire channel is not available, however it seems that through the beta version of the Graph API, I can mention an entire channel.

I have first tried via Graph Explorer, changing the VERB to POST and setting the URL to <https://graph.microsoft.com/beta/teams/{group ID}/channels/{channel id}/messages>

Moreover added the below request body

{
    "subject": "@Mention in Teams channel post!",
    "body": {
        "content": "Hello <at id ='0'>{channel name}</at>, Test message on the channel with at mention.",
        "contentType": "html"
    },
    "mentions": [
        {
            "id": 0,
            "mentionText": "{channel name}",
            "mentioned": {
                "conversation": {
                    "id": "{channel id}",
                    "displayName": "{channel name}",
                    "conversationIdentityType@odata.type": "#Microsoft.Teams.GraphSvc.conversationIdentityType",
                    "conversationIdentityType": "channel"
                }
            }
        }
    ]
}

When the Run Query is pressed, the message is successfully posted and the channel is mentioned. I've then retrieved the code snippet from the graph explorer for C# code, which resulted in the below code

GraphServiceClient graphClient = new GraphServiceClient(authProvider);

var chatMessage = new ChatMessage
{
    Subject = "@Mention in Teams channel post!",
    Body = new ItemBody
    {
        Content = "Hello <at id ='0'>{channel name}</at>, Test message on the channel with at mention.",
        ContentType = BodyType.Html
    },
    Mentions = new List<ChatMessageMention>()
    {
        new ChatMessageMention
        {
            Id = 0,
            MentionText = "{channel name}",
            Mentioned = new IdentitySet
            {
                AdditionalData = new Dictionary<string, object>()
                {
                    {"conversation", "{\"id\":\"{channel id}\",\"displayName\":\"{channel name}\",\"conversationIdentityType@odata.type\":\"#Microsoft.Teams.GraphSvc.conversationIdentityType\",\"conversationIdentityType\":\"channel\"}"}
                }
            }
        }
    }
};

await graphClient.Teams["{group id}"].Channels["{channel id}"].Messages
    .Request()
    .AddAsync(chatMessage);

However when executing the code, the error below is displayed:

ServiceException: Code: BadRequest Message: Invalid request body was sent.

Removing the Mentions or changing the mentions to make use of the User works successfully. Also, kindly note that I've tried using both the Microsoft.Graph and Microsoft.Graph.Beta

Answer 1

I had done a long research on this and found that its a Deserialization issue happening on the Graph server because of the code written this way. The main problem is with the conversation in the Mentioned property. The Graph server was unable to understand the serialized content so try deserializing it before sending the request as shown below.

Identity A = JsonConvert.DeserializeObject<Identity>("{\"id\":\"{channel id}\",\"displayName\":\"{channel name}\",\"conversationIdentityType@odata.type\":\"#Microsoft.Teams.GraphSvc.conversationIdentityType\",\"conversationIdentityType\":\"channel\"}");
            var chatMessage = new ChatMessage
            {
                Subject = "@Mention in Teams channel post!",
                Body = new ItemBody
                {
                    Content = "Hello <at id ='0'>General</at>, Test message on the channel with at mention.",
                    ContentType = BodyType.Html
                },
                Mentions = new List<ChatMessageMention>()
                {
                    new ChatMessageMention
                    {
                        Id = 0,
                        MentionText = "General",
                        Mentioned = new IdentitySet
                        {
                            AdditionalData = new Dictionary<string, object>()
                            {
                                {"conversation", A}
                            }
                        }
                    }
                }
            };
            
            try
            {
                await graphClient.Teams["d3b31e36-d63d-4bbe-9478-b4cc7cb17a3d"].Channels["19:342b9f379eb340048b16d9859d9e3712@thread.tacv2"].Messages
                .Request()
                .AddAsync(chatMessage);

            }
            catch(Exception e)
            {
                Console.WriteLine(e);
            }
        }

It will work.