Update MetaData column for document library using REST C#

Question

I am trying to update the Metadata information for a file in Document Library. I am following this article.

The REST End point used in given article is

var restSource = appweburl +"/_api/SP.AppContextSite(@target)/web/lists/getbytitle('Documents')/rootfolder/files/getbyurl(url='" + fileUrl + "')/listitemallfields?@target='" + hostweburl + "'";

But I am working on Premises. So I customized this end point as:

var url = siteUrl + "_api/Web/GetFolderByServerRelativeUrl('libraryName/FodlerName/documentSetName')/Files/getbyurl(url='FileName')/listitemallfields";

My full code which I am using is

var digest = GetFormDigest();

    if (!string.IsNullOrEmpty(digest))
    {
      var url = siteUrl + "_api/Web/GetFolderByServerRelativeUrl('" + libraryName + "/Tss_RootFolder/" + documentSetName + "')/Files/getbyurl(url='" + fileName + "')/listitemallfields";
      var body = "{ '__metadata': {'type':'SP.ListItem'},'Title': 'My Title 3'}";
      var client = new WebClient();
      client.Credentials = creds;
      client.Headers[HttpRequestHeader.Accept] = "application/json;odata=verbose";
      client.Headers[HttpRequestHeader.ContentType] = "application/json;odata=verbose";
      client.Headers["X-RequestDigest"] = digest;
      client.Headers["If-Match"] = "*";
      client.Headers["X-Http-Method"] = "PATCH";
      var json = client.UploadString(url, body); }

My file is located in Document Library >> Root Folder >> Document Set >> File.

Am I using correct REST end point? Because I am always getting 400 (Bad Request) error.

I already gone through several similar question on SE but not able to find any proper solution.

I am not working on SharePoint Environment so No CSOM and SSOM codes will work for me.

Edit: I changed my REST Endpoint to:

var url = siteUrl + "_api/Web/GetFolderByServerRelativeUrl('" + libraryName + "/Tss_RootFolder/" + documentSetName + "')/Files/getbyurl(url='" + fileName + "')/listitemallfields/Title";

No I am not getting 400 (Bad Request) Error but the fields also not get updated.

Any help or suggestion will be appreciated.

Answer 1

Finally after working more than 2 days I found the solution. Actually I was making a mistake in using GetFileByServerRelativeUrl() method.

I was using url as:

var url = siteUrl + "_api/Web/GetFolderByServerRelativeUrl('" + libraryName + "/Tss_RootFolder/" + documentSetName + "')/Files/getbyurl(url='" + fileName + "')/listitemallfields";

I just changed the url as

var url = siteUrl + "_api/Web/GetFileByServerRelativeUrl('/sites/subSiteName/" + libraryName + "/Tss_RootFolder/" + documentSetName + "/" + fileName + "')/ListItemAllFields";

And the Metadata was updated.