Hi,

First, create a new property on the page and fill it with the value that you have for the selected category.

public virtual IEnumerable<string> SearchCategories {
            get {
                var main = !ContentReference.IsNullOrEmpty(this.MainCategory) ? new List<string> { this.MainCategory.ID.ToString() } : new List<string>();
                return main;
            }
        }    

Then on the search function -  you can use "BuildFilter" to do this task.

var categoriesFilterBuilder = _client.BuildFilter<BaseFeedPage>();

if (categories != null)
            {
                foreach (var filter in categories)
                {
                    categoriesFilterBuilder = categoriesFilterBuilder.Or(x => x.SearchCategories.Match(filter));
                }
            }

var searchQuery = this._client.Search<T>();
 searchQuery = searchQuery.Filter(categoriesFilterBuilder);
var batch = searchQuery.GetContentResult();

Regards

Ravindra

You can't sort a list using a bool by passing it to OrderBy. Like you did in your code

ThenByDescending(x=>x.MainCategoryForFind.Match(desiredcategory))

You can filter the query first and then sort it

searchclient.Search<CourseProduct.CoursProduct>()
.Filter(x=> x.MatchTypeHierarchy(typeof(T)))
.FilterForVisitor()
.Filter(x=>x.MainCategoryForFind.Match(desiredcategory))
.OrderByDescending(x=> x.Featured)
.OrderByDescending(x=> x.MainCategoryForFind)
.ThenByDescending(x=>x.Created);