Users[userId].MailFolders[mailFolderId].Messages[messageId].Attachments.ContentBytes does not appear to be base64 encoded

[catmanjan]

Describe the bug

According to the summary comment ContentBytes is "The base64-encoded contents of the file."

However the bytes do not appear to be base64 encoded, because if I try to decode them I get an error that it is not base64 encoded

Expected behavior

Probably the comment needs to be verified

How to reproduce

var attachment = await graphClient.Users[userId].MailFolders[mailFolderId].Messages[messageId].Attachments[attachmentId]
.GetAsync() as FileAttachment;

var bytes = attachment.ContentBytes;
var base64Chars = Encoding.UTF8.GetChars(attachment.ContentBytes);
var decodedBytes = Convert.FromBase64CharArray(base64Chars, 0, base64Chars.Length);

Throws an error

SDK Version

No response

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

Click to expand log

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</details>


### Configuration

_No response_

### Other information

_No response_

[andrueastman]

Thanks for raising this @catmanjan

I believe the byte array should already be base64 decoded. Decoding the ContentBytes property would be performing a second decode which would fail.

For reference see the implementation links below.

• https://github.com/microsoftgraph/msgraph-sdk-dotnet/blob/5967b8a3e1da5659b2f3ed245c6ccc10e6d722f9/src/Microsoft.Graph/Generated/Models/FileAttachment.cs#L88C59-L88C76
• https://github.com/microsoft/kiota-dotnet/blob/273e23072904ded60e22a434013475975d80049a/src/serialization/json/JsonParseNode.cs#L271

[catmanjan]

Thanks, if that's true shouldn't the comment not say that it is base64 encoded?

…

On Mon, 17 Feb 2025, 8:30 pm Andrew Omondi, ***@***.***> wrote: Thanks for raising this @catmanjan <https://github.com/catmanjan> I believe the byte array should already be base64 decoded. Decoding the ContentBytes property would be performing a second decode which would fail. For reference see the implementation links below. - https://github.com/microsoftgraph/msgraph-sdk-dotnet/blob/5967b8a3e1da5659b2f3ed245c6ccc10e6d722f9/src/Microsoft.Graph/Generated/Models/FileAttachment.cs#L88C59-L88C76 - https://github.com/microsoft/kiota-dotnet/blob/273e23072904ded60e22a434013475975d80049a/src/serialization/json/JsonParseNode.cs#L271 — Reply to this email directly, view it on GitHub <#2836 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBRBWQXVHEXTHBGFR5JNT2QGT2DAVCNFSM6AAAAABXIGOX22VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMNRSGUZTENJZGA> . You are receiving this because you were mentioned.Message ID: ***@***.***> [image: andrueastman]*andrueastman* left a comment (microsoftgraph/msgraph-sdk-dotnet#2836) <#2836 (comment)> Thanks for raising this @catmanjan <https://github.com/catmanjan> I believe the byte array should already be base64 decoded. Decoding the ContentBytes property would be performing a second decode which would fail. For reference see the implementation links below. - https://github.com/microsoftgraph/msgraph-sdk-dotnet/blob/5967b8a3e1da5659b2f3ed245c6ccc10e6d722f9/src/Microsoft.Graph/Generated/Models/FileAttachment.cs#L88C59-L88C76 - https://github.com/microsoft/kiota-dotnet/blob/273e23072904ded60e22a434013475975d80049a/src/serialization/json/JsonParseNode.cs#L271 — Reply to this email directly, view it on GitHub <#2836 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABBRBWQXVHEXTHBGFR5JNT2QGT2DAVCNFSM6AAAAABXIGOX22VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMNRSGUZTENJZGA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[andrueastman]

That's true. The contents do come from the API as a base64 encoded string. But the SDK changes this to a byte array.

The SDK generation process does however pull the property information from the public documentation which is the real source of the confusion here. https://learn.microsoft.com/en-us/graph/api/resources/fileattachment?view=graph-rest-1.0#properties