Display specifc documents with where condition

Hello Dev i was trying to display data based on this code but display only 3 page type where field is true here is my code I already try it but get an error

private void GetDataRowOutput(DataRowView drv, StringBuilder sb, GroupedDataSource gpd)
    {
        sb.Append("<li><a href=\"")
            .Append(URLHelper.GetAbsoluteUrl(DocumentURLProvider.GetUrl(drv["NodeAliasPath"].ToString())))
            .Append("\" title=\"")
            .Append(drv["DocumentName"])
            .Append("\" class=\"")
            .Append(drv["ClassName"])
            .Append("\">")
            .Append(drv["DocumentName"])
            .Append("</a>")
            .Append("</li>");
        int nodeID = Convert.ToInt32(drv["NodeID"]);
        var items = gpd.GetGroupView(nodeID);
        if (items != null)
        {
            sb.Append("<ul>");
            foreach (var i in items) GetDataRowOutput(i, sb, gpd);
            sb.Append("</ul>");
        }
    }

    public string GetSiteMap()
    {
        StringBuilder sb = new StringBuilder();
        sb.Append("<ul>");

        var ds = DocumentHelper.GetDocuments()
        .OnCurrentSite()
        .Columns("NodeLevel", "NodeOrder", "NodeName", "NodeParentID", "NodeAliasPath", "DocumentName", "NodeID", "ClassName")
        .OrderBy("NodeLevel, NodeOrder, NodeName")
        .Result;

        GroupedDataSource gpd = new GroupedDataSource(ds, "NodeParentID", "NodeLevel");
        var items = gpd.GetGroupView(0);
        foreach (DataRowView drv in items)
        {
            GetDataRowOutput(drv, sb, gpd);
        }
        sb.Append("</ul>");
        return sb.ToString();
    }

}