C# CSOM - Check if File Exists in Document Library

Junior picture Junior · Mar 11, 2015 · Viewed 24.6k times · Source

I'm coding in C# using CSOM, my app uploads a template asp.net page to the "/Pages/" library, I need it to check if a file exists in that location with the same name prior to file upload (then maybe it can return a bool value).

I did have a quick look but the majority of the solutions I found referred to the use of Javascript, or applied to on-prem deployments.

If someone could please point me in the right direction I would appreciate it.

Answer

Vadim Gremyachev picture Vadim Gremyachev · Mar 11, 2015

You could consider the following approaches to determine whether file exists or not.

Query based

You could construct CAML query to find list item by its Url as demonstrated below:

public static bool FileExists(List list, string fileUrl)
{
    var ctx = list.Context;
    var qry = new CamlQuery();
    qry.ViewXml = string.Format("<View Scope=\"RecursiveAll\"><Query><Where><Eq><FieldRef Name=\"FileRef\"/><Value Type=\"Url\">{0}</Value></Eq></Where></Query></View>",fileUrl);
    var items = list.GetItems(qry);
    ctx.Load(items);
    ctx.ExecuteQuery();
    return items.Count > 0;
}

Usage

using (var ctx = GetSPOContext(webUri,userName,password))
{
     var list = ctx.Web.Lists.GetByTitle(listTitle);
     if(FileExists(list,"/documents/SharePoint User Guide.docx"))
     {
          //...
     }
}

Web.GetFileByServerRelativeUrl Method

Use Web.GetFileByServerRelativeUrl Method to return the file object located at the specified server-relative URL.

If file does not exists the exception Microsoft.SharePoint.Client.ServerException will be encountered:

  public static bool TryGetFileByServerRelativeUrl(Web web, string serverRelativeUrl,out Microsoft.SharePoint.Client.File file)
    {
        var ctx = web.Context;
        try{
            file = web.GetFileByServerRelativeUrl(serverRelativeUrl);
            ctx.Load(file);
            ctx.ExecuteQuery();
            return true;
        }
        catch(Microsoft.SharePoint.Client.ServerException ex){
            if (ex.ServerErrorTypeName == "System.IO.FileNotFoundException")
            {
                file = null;
                return false;
            }
            else
                throw;
        }
    }

Usage:

 using (var ctx = GetSPOContext(webUri,userName,password))
 {
      Microsoft.SharePoint.Client.File file;
      if(TryGetFileByServerRelativeUrl(ctx.Web,"/documents/SharePoint User Guide.docx",out file))
      {
          //...
      }
 }