var Categoryid = customEntityResult.Items.Select(x => (BlogPostDataModel)x.Model).Select(x => x.CategoryIds).FirstOrDefault();
var result = customEntityResult.Items.Select(x => (BlogPostDataModel)x.Model).Where(x => x.CategoryIds==Categoryid).ToList();
Here GetRecord base on id for e,g one category under Two Post .
But i have face a issue only one record get not two record.