"No records to display" in Telerik's TreeList
<p>I have simple TreeList, which I want to be filled up with some values.
My TreeList:</p>

<pre><code>@(Html.Kendo().TreeList&lt;Book&gt;()
            .Name("BooksTreeList")
            .Columns(columns =&gt;
            {
                columns.Add().Field(c =&gt; c.BookName);
                columns.Add().Field(c =&gt; c.BookAuthor);
            })
            .Filterable()
            .Sortable()
            .DataSource(dataSource =&gt; dataSource
                .Read(read =&gt; read.Action("ReadAllBooks", "Catalog"))
                .ServerOperation(false)
                .Model(m =&gt;
                {
                    m.Id(c =&gt; c.BookId);
                    m.ParentId(c =&gt; c.ParentId);
                    m.Expanded(true);
                    m.Field(x =&gt; x.BookId);
                    m.Field(x =&gt; x.BookAuthor);
                })
            ))
</code></pre>

<p>And my controller class:</p>

<pre><code>public async Task&lt;IActionResult&gt; ReadAllBooks([DataSourceRequest] DataSourceRequest request)
{
    var result = (await GetAllBooks())
      .ToTreeDataSourceResult(
      request,
      x =&gt; x.BookId,
      x =&gt; x.ParentId);
    return Json(result);
}
private async Task&lt;List&lt;BookViewModel&gt;&gt; GetAllBooks()
{
   return await _dbContext.Books.Select(x =&gt; new BookViewModel()
   {
      BookId = x.CodingId,
      BookName = x.BookName,
      BookAuthor = x.BookAuthor,
      ParentId = x.ParentId
   }).ToListAsync();
}
</code></pre>

<p>But when I'm entering the page, my treelist always shows "No records to display" even if I have records, I checked it with the help of the debugger.
How should I fill my TreeList correctly?</p>