How to download an image from Azure DevOps Services HTML Field using API

1
votes

I want to download Work Item details from our Azure DevOps Services instance and push it into our local TFS Server.

I got as far as connecting to the DevOps server using the WorkItemTrackingHttpClient in C#. I can iterate through the work items i find and can see the fields, download attachments using GetAttachmentContentAsync. So far all good.

The last detail i need to complete this is to also copy/download the embedded images that are in the HTML Description fields. I can extract the HTML code from the HTML field and see one or more img src lines in it.

<img src=\"https://dev.azure.com/tenant/projectguid/_apis/wit/attachments/d928c8ee-f493-4d30-99a5-f62b7f36a2f7?fileName=grafik.png"\>

All of these have the fileName grafik.png, but a different fileGuid.

I tried to use the GetAttachmentContentAsync to download on this guid, but that did not work. I tried to download the file using a normal Stream, but that didnt work, i assume this is due to authentication. The image files also do not show up as a normal attachment.

So the question is, how can i download this image from Azure DevOps from my C# client, which is authenticated using a PAT through the API. Is there an API call i can use to download this file ? i have not been able to find it, or can i somehow authenticate the WebClient with that PAT so that it can download it ?

1
azure-devops

1 Answers

1
votes

After further troubleshooting, now the GetAttachmentContentAsync is able to download the image.

For anyone what might be looking for a similar solution. This is what i did

Code used to download

public string DownloadAttachment(string url, string fileName, int workItemId)

    {
        string[] urlSplit = url.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
        int index = urlSplit.Length - 1;
        Guid attGuid = new Guid(urlSplit[(index)]);

        if (fileName == string.Empty)
        {
            fileName = urlSplit[(index)] + ".png";
        }
        return DownloadAttachment(attGuid, fileName, workItemId);
    }

    public string DownloadAttachment(Guid attGuid, string fileName, int workItemId)
    {
        var credentials = new VssBasicCredential(string.Empty, this.personalAccessToken);

        // create instance of work item tracking http client
        using (var httpClient = new WorkItemTrackingHttpClient(this.uri, credentials))
        {
            Stream attStream = httpClient.GetAttachmentContentAsync(attGuid).Result;

            string folderPath = @"C:\Temp\WorkItemAttachments\" + workItemId;
            string fileFullPath = folderPath + "\\" + fileName;
            Directory.CreateDirectory(folderPath);

            using (FileStream writeStream = new FileStream(fileFullPath, FileMode.Create, FileAccess.ReadWrite))
            {
                attStream.CopyTo(writeStream);
            }
        }

        return fileName;

    }