How to retrieve contents of an itemAttachment via the Microsoft Graph API - microsoft-graph-api

Question

I'm currently developing a solution which is retrieving e-mails via the Microsoft Graph API. In november 2015 Microsoft stated it is ready for production and I've read in another forum post that if you start now on developing using a Microsoft API, you should use the Graph API, since it is the future.
Everything is going well except for one thing and that is the following.
I must retrieve e-mails. Inside these e-mails there are of course attachments. These attachments come in some variaties. fileAttachment (images, documents etc.), referenceAttachments and itemAttachments (outlook-item). The issue here is with the itemAttachments. An itemAttachment can be anything from an appointment to another message. The problem here is that I'm not able to get and retrieve the contentBytes in some way which is working for fileAttachments. A related object to itemAttachment is outlookItem. There is also a page with a description made for this outlookItem, but the examples and the details are missing.
The user rights are set to Mail.Read and Mail.ReadWrite.
Links:
General overview: http://graph.microsoft.io/docs/overview/overview
Get outlookItem (empty?):
Example call and response I get. Please note the types of the attachments.
https://graph.microsoft.com/v1.0 /users/ /messages/ /attachments
{
"#odata.context": "link",
"value": [
{
"#odata.type": "#microsoft.graph.fileAttachment",
"id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAGhN_vm1RlBPt7V4N9a89UY=",
"lastModifiedDateTime": "2016-01-13T14:25:33Z",
"name": "image001.png",
"contentType": "image/png",
"size": 5077,
"isInline": true,
"contentId": "image001.png#01D14E16.A3A32480",
"contentLocation": null,
"contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAKAAAACCCAIAAABOyVRHAAAAAXNSR0IArs4c6QAAEndJREFUeF7tXQ1QFFe2bkbU... (truncated)"
},
{
"#odata.type": "#microsoft.graph.fileAttachment",
"id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAFnSLgIC5wZOosmLtBWK8gE=",
"lastModifiedDateTime": "2016-01-13T14:25:34Z",
"name": "image002.png",
"contentType": "image/png",
"size": 3722,
"isInline": true,
"contentId": "image002.png#01D14E16.A3A32480",
"contentLocation": null,
"contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAPoAAABSCAYAAAB9o8m+AAAAGXRFWHRTb... (truncated)"
},
{
"#odata.type": "#microsoft.graph.fileAttachment",
"id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQANOuw7m8sW1Ot3MivYQ5OYU=",
"lastModifiedDateTime": "2016-01-13T14:25:24Z",
"name": "Knipsel.PNG",
"contentType": null,
"size": 7641,
"isInline": false,
"contentId": null,
"contentLocation": null,
"contentBytes": "iVBORw0KGgoAAAANSUhEUgAAAKAAAACCCAYAAADBq8MQAAA... (truncated)"
},
{
"#odata.type": "#microsoft.graph.itemAttachment",
"id": "AAMkAGU2NmIwMTcxLTljYzUtNGRiMi1hZjczLTllNzhiZDRiNWZlZABGAAAAPAD_Lx_gimDGRqSr98J_O_e6BwDcWyYHlO7rS5_XpLHCx6NSAAIMC0V-AADcWyYHlO7rS5_XpLHCx6NSAAIMC6RgAAABEgAQAPEUC740tjtAlNTe8NpopUI=",
"lastModifiedDateTime": "2016-01-14T15:55:07Z",
"name": "RE: Test met plaatje",
"contentType": null,
"size": 36972,
"isInline": false
}
]
}
I've tried to change the GET-statement by pasting the attachment id with or without the messages path and the expand feature (which is only supported one level deep), but I can't seem te find the solution.
Something I've found is this question, which is kind of the same, however it is for the office365 unified API. How to retrieve ItemAttachment contents from Office 365 REST API?.
So, the question: How can I retrieve the contents of an outlookItem via the Microsoft Graph API? And how do I know what to expect? Can anybody help me getting past this obstacle.

Answer 1

Use $expand option:
GET https://graph.microsoft.com/v1.0/me/messages('AAMkADA1M-zAAA=')/attachments('AAMkADA1M-CJKtzmnlcqVgqI=')/?$expand=microsoft.graph.itemattachment/item
Response:
HTTP/1.1 200 OK
Content-type: application/json
{
"#odata.context":"https://graph.microsoft.com/v1.0/$metadata#users('d1a2fae9-db66-4cc9-8133-2184c77af1b8')/messages('AAMkADA1M-zAAA%3D')/attachments/$entity",
"#odata.type":"#microsoft.graph.itemAttachment",
"id":"AAMkADA1MCJKtzmnlcqVgqI=",
"lastModifiedDateTime":"2017-07-21T00:20:34Z",
"name":"Reminder - please bring laptop",
"contentType":null,
"size":32005,
"isInline":false,
"item#odata.context":"https://graph.microsoft.com/v1.0/$metadata#users('d1a2fae9-db66-4cc9-8133-2184c77af1b8')/messages('AAMkADA1M-zAAA%3D')/attachments('AAMkADA1M-CJKtzmnlcqVgqI%3D')/microsoft.graph.itemAttachment/item/$entity",
"item":{
"#odata.type":"#microsoft.graph.message",
"id":"",
"createdDateTime":"2017-07-21T00:20:41Z",
"lastModifiedDateTime":"2017-07-21T00:20:34Z",
"receivedDateTime":"2017-07-21T00:19:55Z",
"sentDateTime":"2017-07-21T00:19:52Z",
"hasAttachments":false,
"internetMessageId":"<BY2PR15MB05189A084C01F466709E414F9CA40#BY2PR15MB0518.namprd15.prod.outlook.com>",
"subject":"Reminder - please bring laptop",
"importance":"normal",
"conversationId":"AAQkADA1MzMyOGI4LTlkZDctNDkzYy05M2RiLTdiN2E1NDE3MTRkOQAQAMG_NSCMBqdKrLa2EmR-lO0=",
"isDeliveryReceiptRequested":false,
"isReadReceiptRequested":false,
"isRead":false,
"isDraft":false,
"webLink":"https://outlook.office365.com/owa/?ItemID=AAMkADA1M3MTRkOQAAAA%3D%3D&exvsurl=1&viewmodel=ReadMessageItem",
"body":{
"contentType":"html",
"content":"<html><head>\r\n</head>\r\n<body>\r\n</body>\r\n</html>"
},
"sender":{
"emailAddress":{
"name":"Adele Vance",
"address":"AdeleV#contoso.onmicrosoft.com"
}
},
"from":{
"emailAddress":{
"name":"Adele Vance",
"address":"AdeleV#contoso.onmicrosoft.com"
}
},
"toRecipients":[
{
"emailAddress":{
"name":"Alex Wilbur",
"address":"AlexW#contoso.onmicrosoft.com"
}
}
],
"ccRecipients":[
{
"emailAddress":{
"name":"Adele Vance",
"address":"AdeleV#contoso.onmicrosoft.com"
}
}
]
}
}
Source: https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/api/attachment_get#request-2

Answer 2

The official documentation: https://graph.microsoft.io/en-us/docs/api-reference/beta/api/attachment_get.htm . Use valid Bearer authentication access code, and check for appropriate Graph API permissions on the Azure management portal. Attachment is based64 encoded string, coming in the contentBytes field. Correct Uri for loading list of a message attachments is: https://graph.microsoft.com/beta/me/messages/[ message Id ]/attachments. Sample code to call attachments endpoint is below:
using (var client = new HttpClient())
{
using (var request = new HttpRequestMessage(HttpMethod.Get,
"https://graph.microsoft.com/beta/me/messages/..id../attachments"))
{
request.Headers.Authorization =
new AuthenticationHeaderValue("Bearer", "...valid access token...");
using (HttpResponseMessage response = await client.SendAsync(request))
{
if (response.StatusCode == HttpStatusCode.OK)
{
result = await response.Content.ReadAsStringAsync();
var json = JObject.Parse(result);
}
}
}
}

Answer 3

Get attachment using MS Graph API for Java:
First build the graph client. Sample code
ClientSecretCredential clientSecretCredential = new ClientSecretCredentialBuilder()
.clientId(yourClientId).clientSecret(yourClientSecret)
.tenantId(yourTenantId).build();
TokenCredentialAuthProvider tokenCredAuthProvider = new TokenCredentialAuthProvider(clientSecretCredential);
GraphServiceClient<Request> gClient = GraphServiceClient.builder().authenticationProvider(tokenCredAuthProvider)
.buildClient();
Either get all the attachments for a message-
FileAttachment fa = (FileAttachment) graphClient.users(id).messages(messageId).attachments().buildRequest().get();
Or get a particular attachment by passing the attachment id:
FileAttachment fa = (FileAttachment) graphClient.users(id).messages(messageId).attachments(attachmentId).buildRequest().get();
//Copy file attachment into a File from byte stream using FileUtils.
FileUtils.writeByteArrayToFile(new File(yourFileLocation), fa.contentBytes);
You can also similarly either get all users, messages or attachments or pass particular id to get a unique result for these entities.