Sharepoint Rest API, c#, update document metadata

Question

I'm trying to update one metadata field - "myToAddress". There are others, but one is good for now. I keep getting "400 bad request". Quite certain the RequestDigest is ok, since I'm able to upload a document.

Here's the code:

public static void UpdateMetaData()
    {
        var uri = new Uri(https://example.com/sites/docs/_api/web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/testMail.msg')"
        var request = WebRequest.Create(uri) as HttpWebRequest;
        request.Credentials = new NetworkCredential(""xxx", "yyy", "zzz");
        request.Method = "POST";
        request.Accept = "application/json; odata=verbose";
        request.ContentType = "application/json; odata=verbose";
        request.Headers.Add("X-HTTP-Method", "MERGE");
        request.Headers.Add("IF-MATCH", "*");
        request.Headers.Add("X-RequestDigest", GetFormDigest());

        string stringData =   "{'__metadata': { 'type': 'SP.File'},'ListItemAllFields': {'__metadata': { 'type': 'SP.Data.EmailItem'}, 'myToAddress': '[email protected]'}}";
        request.ContentLength = stringData.Length;

        StreamWriter writer = new StreamWriter(request.GetRequestStream());
        writer.Write(stringData);
        writer.Flush();

        using (var response = (HttpWebResponse)request.GetResponse())
        {
            using (var reader = new StreamReader(response.GetResponseStream()))
            {
                reader.ReadToEnd();
            }
        }
    }

}

Is stringData formed correctly? I suspect that's the problem - but i don't know how to fix it. Maybe you have to include all of the metadata fields in stringData - not just the one you want to update. It looks like all fields are included in this javascript example: SharePoint 2013 REST api to update list item- Uncaught ReferenceError: etag is not defined

Can you perform an "update" using GetFileByServerRelativeURL?

Is the uri formed correctly? (Do i need change the uri to 'select' or 'expand' fields.)

To see the shape of the metadata i used this "Get" request URI for the document:

    var uri = new Uri(https://example.com/sites/docs/_api/web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/TestMail.msg')?$expand=ListItemAllFields&$select=ListItemAllFields/myToAddress";

The json string per the "Get" request on the document looks like this:

{"d":{"__metadata":            {"id":"Web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/testMail.msg')","uri":"https://example.com/sites/docs/_api/Web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/testMail.msg')","type":"SP.File"},"ListItemAllFields":{"__metadata":{"id":"Web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/testMail.msg')/ListItemAllFields","uri":"https://example.com/sites/docs/_api/Web/GetFileByServerRelativeUrl('/sites/docs/Email/TestFolder/testMail.msg')/ListItemAllFields","etag":"\"1\"","type":"SP.Data.EmailItem"},"myToAddress":null}}}

I'm using code almost exactly like the code in UpdateListItem here: https://social.msdn.microsoft.com/Forums/sqlserver/en-US/40833576-5853-4ca4-95cf-b5b1d69f465f/sharepoint-rest-and-c-sample-to-update-list-item?forum=sharepointdevelopment. But something's not working for me.

Answer 1

Basically this error occurs since endpoint /_api/web/GetFileByServerRelativeUrl('<file url>') could not be used for updating document metadata (or list item associated with a file)

Instead you could utilize /_api/web/GetFileByServerRelativeUrl('<file url>')/ListItemAllFields endpoint for that purpose, for example:

Uri: /_api/web/GetFileByServerRelativeUrl('<file url>')/ListItemAllFields
Method: POST
body: { '__metadata': { 'type': 'SP.Data.DocumentsItem' }, 'Note': 'Content goes here' }
Headers: 
    X-RequestDigest: form digest value
    IF-MATCH": etag or "*"
    X-HTTP-Method: MERGE,
    accept: "application/json;odata=verbose"
    content-type: "application/json;odata=verbose"

Example

var fileUrl = "/Documents/User Guide.docx";
using (var client = new SPWebClient(webUri.ToString()))
{
       client.Credentials = GetCredentials(webUri, userName, password);

       var requestUrl = string.Format("/_api/web/GetFileByServerRelativeUrl('{0}')/ListItemAllFields", fileUrl);
       var payload = new JObject
       {
                ["Notes"] = "Some comments goes here",
                ["__metadata"] = new JObject {["type"] = "SP.Data.DocumentsItem" }
       };
       var updateHeaders = new Dictionary<string,string>();
       updateHeaders["X-HTTP-Method"] = "MERGE";
       updateHeaders["If-Match"] = "*";
       client.ExecuteJsonWithDigest(requestUrl, "POST", updateHeaders, payload);
}

Dependencies

SPWebClient.cs - a WebClient class with a SharePoint specific methods.

Answer 2

@Vadim

you can add this method as well to you SPWebClient then you don't have to know SP.Data.DocumentsItem to make it more dynamic

public string GetItemTypeForListName(string listTitle)
        {
            StreamReader reader;

            var url = WebUri + $"/_api/web/lists/getbytitle('{listTitle}')/?$select=ListItemEntityTypeFullName";
            var endpointUri = new Uri(url);

            Stream stream = _client.OpenRead(endpointUri);
            reader = new StreamReader(stream);
            var result = reader.ReadToEnd();
            JToken t = JToken.Parse(result);

            return t["d"]["ListItemEntityTypeFullName"].ToString();

        }