CODEWITHSUNDEEP
c#linq
user1470994
user1470994

Reputation: 311

Variables in Select Statement

I have the following function:

    public List<TopMediansModel> QueryForMedians(string state, string median)
    {
        ApplicationDbContext db = new ApplicationDbContext();
        return (from q in db.StateSuburbLocation
                where (q.State == state)
                orderby q.GetType().GetProperty(median) descending
                select new TopMediansModel
                {
                    Median = median,
                    MedianValue = q.GetType().GetProperty(median),
                    MedianSuburb = q.Suburb
                }).Take(10).ToList();
    }

Is it possible to have the orderby and MedianValue 'properties' as variables?

I've tried using the GetType().GetProperty() Methods, and am no doubt doing so incorrectly.

Upvotes: 0

Views: 73

Answers (1)

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236328

You can use something like Dynamic Linq

return db.StateSuburbLocation
         .Where(l => l.State == state)
         .OrderByDescending(median)
         .Select(l => new TopMediansModel {
             Median = median,
             MedianValue = q.GetType().GetProperty(median),
             MedianSuburb = q.Suburb
          }).Take(10).ToList();

Or you can build query expression manually

    public static IQueryable<T> OrderByDescending<T>(
        this IQueryable<T> source, string propertyName)
    {         
        var parameter = Expression.Parameter(typeof(T), "p");
        var property = Expression.PropertyOrField(parameter, propertyName);
        var keySelector = Expression.Lambda<Func<T, object>>(property, parameter);
        return source.OrderByDescending(keySelector);
    }

Usage is same

Upvotes: 2

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