Download file attachments from an Azure bot

Follow these steps to download attachments from an Azure bot in Omnichannel.

1. Get the token for your bot using your bot's Microsoft App ID and client secret.

2. Get the attachmentId from the attachment URL.

   For example, if the URL is https://us-api.asm.skype.com/v1/objects/0-eus-d1-5360689c55c308cb4e3b51722e46b801/, then the attachmentId is 0-eus-d1-5360689c55c308cb4e3b51722e46b801.

3. Insert the attachmentId in a RequestUri variable and then use RequestUri in a GET request, like this:

   string requestUri = $"https://botapi.skype.com/amer/v3/attachments/{attachmentId}/views/original";
   var httpRequest = new HttpRequestMessage(HttpMethod.Get, requestUri);
   
   var authorization = new AuthenticationHeaderValue("bearer", <add the botToken here>);
   var requestHeaders = new Dictionary<string, string>()
     {
        { "Authorization", authorization.ToString() }
     };
   
   foreach (var header in requestHeaders)
     {
         httpRequest.Headers.Add(header.Key, header.Value);
     }
   
   HttpResponseMessage response = await client.SendAsync(httpRequest);
   

Manage file attachments

This section describes how to manage file attachments in the Omnichannel bot service messaging platform.

First, let's quickly review file attachment formats in the Omnichannel bot service channel.

File attachment formats

When file attachments are sent from Omnichannel for Customer Service to the Azure bot on the Omnichannel bot service channel, the information required to download the files is passed in the amsReferences and amsMetadata fields of the Activity.ChannelData property.

Omnichannel bot service channel

{
   "recipient":{
      "id":"8:acs:5ecf37b1-11 Oc-414g-ab33-804ffd6b4a33_eooe0010-7c57-1ceb-nec-113aOdOOb272",
      "name":"Omnichannel-test-bot",
      "aadObjectId":null,
      "role":null
   },
   "attachments ":null,
   "channelData":{
      "tags":"Channelld-lcw,FromCustomer",
      "deliveryMode":"bridged",
      "fromUserId":"8:acs:5ecf37b1-110c-4149-ab33-804ffd6b4a33_00000010-61 b9-ab1 d-3dfe-9c3aOd009ea4",
      "amsReferences":[
         "0-wus-d6-20e7797d208fab388cc11b09674d166"
      ],
      "amsMetadata":[
         {
            "contentType":"image/png",
            "fileName":"SurnmerTime.png"
         }
      ],
      "sourceChannelId":"omnichannel"
   }
}

How to manage file attachments in your Azure bot code

Attachment information is passed in the Omnichannel bot service channel, and can be accessed in bot code, as shown in the following example.

// 1. Retrieve Attachment ID from ChannelData["amsReferences"]
if (turnContext.Activity.ChannelData != null &&
    turnContext.Activity.ChannelData is JObject incomingRequestChannelData &&
    incomingRequestChannelData.TryGetValue("amsReferences", out JToken amsReferencesArray))
{
    string attachmentId = JsonConvert.DeserializeObject<string[]>(amsReferencesArray.ToString()).FirstOrDefault();

    // 2. Build HTTP request for specified attachment ID.
    string requestUri = $"https://botapi.skype.com/amer/v3/attachments/{attachmentId}/views/original";
    var httpRequest = new HttpRequestMessage(HttpMethod.Get, requestUri);

    // 3. Acquire authentication token and add it to request headers
    var token = await new MicrosoftAppCredentials("botAppId", "botAppSecret").GetTokenAsync();
    var authorization = new AuthenticationHeaderValue("bearer", token);
    httpRequest.Headers.Add("Authorization", authorization.ToString());

    // 4. Add Azure Communication Services Bot ID to request header. This is required to achieve good download performance.
    httpRequest.Headers.Add("BotAcsId", turnContext.Activity.Recipient.Id);

    // 5. Use HttpClient to execute the request and download attachment
    var response = await client.SendAsync(httpRequest);
    
    // 6. Save HTTP response stream to the file
    var responseContentStream = await response.Content.ReadAsStreamAsync();
    using (FileStream fileCreateStream = new FileStream("file path", FileMode.Create))
    {
        fileCreateStream.CopyTo(responseContentStream);
    }
}

Related information

Card support by channel
Support for live chat and asynchronous channels
Migration changes for new omnichannel messaging platform