Getting image from Sharepoint post with Microsoft Graph - image

Question

My company has made a custom photo-field in Sharepoint for it's news. I'm trying to use Microsoft Graph to fetch the images, but with no success.
This is the columns description:
{
"columnGroup": "Page Layout Columns",
"description": "",
"displayName": "Thumbnail image",
"enforceUniqueValues": false,
"hidden": false,
"id": "XXXXXXX-XXXX-XXXX-XXX-XXXXXXXXXXXX",
"indexed": false,
"name": "PublishingPageImage",
"readOnly": false,
"required": false
},
In the documentation for Microsoft Graph it is written that you can make a request like this
GET https://graph.microsoft.com/beta/sites/{site-id}/lists/{list-id}/items?expand=fields(select=Column1,Column2)
Although - no matter how I seem to write the request, i can't get the image field.
My most recent try has been this request:
https://graph.microsoft.com/beta/sites/knowit.sharepoint.com/lists/posts/items?expand=fields(select=PublishingPageImage)
The respons I got from Microsoft was this:
{
"error": {
"code": "-1, Microsoft.SharePoint.Client.ClientServiceException",
"message": "Cannot serialize data for type Microsoft.SharePoint.Publishing.Fields.ImageFieldValue.",
"innerError": {
"request-id": "f25e4851-0c1b-4061-ad6a-948d38004046",
"date": "2018-09-17T14:03:01"
}
}
}
Should I use something like .value or .data or .ImageUrl after the request? If i get a link or a data-value doesn't really matter. In the call for /me/ for Microsoft users there is a $value property for getting the user profile photo. Is it something like this?

Answer 1

It depends how image is stored.
If it is attachment you can do following:
string baseURL = $"https://{spTenant}/_api/web/lists('{ AA.config.listID}')/items({ siteData.Id})/AttachmentFiles";
string fileName = await GetFileNameAsync(baseURL);
string getPictureReqUrl = $"{baseURL}('{fileName}')/$value";
Stream responseStream = await GetPictureAsync(getPictureReqUrl);
private static async Task<Stream> GetPictureAsync(string reqUrl)
{
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", SPOToken);
HttpResponseMessage response = await client.GetAsync(reqUrl);
return await response.Content.ReadAsStreamAsync();
}
Important! This is not supported by graph yet, but you can use SharePoint Rest API
If picture is stored in document library you need to use Drive object instead
https://developer.microsoft.com/en-us/graph/docs/api-reference/beta/resources/drive