OrderBy a string in Entity Framework

Posted by Phil in .NET, Entity Framework on Feb 21st, 2012 | 5 comments

I’ve just started using Entity Framework, and I’ve found that it really helps speed up development time when dealing with queries where performance isn’t a huge issue.

I added to an existing project which needed to keep the EF classes isolated in the data layer. This made it difficult to pass in a sort order without having a massive switch statement to deal with each of the options.

I solved this by building an OrderBy extension method that takes a string, and builds the sort expression using reflection. This means you can sort without having to know the actual type of what you’re ordering by.

Here’s the Gist:

public static IQueryable<T> OrderBy<T>(this IQueryable<T> source, string sortExpression) { if (source == null) throw new ArgumentNullException("source", "source is null."); if (string.IsNullOrEmpty(sortExpression)) throw new ArgumentException("sortExpression is null or empty.", "sortExpression"); var parts = sortExpression.Split(' '); var isDescending = false; var propertyName = ""; var tType = typeof(T); if (parts.Length > 0 && parts[0] != "") { propertyName = parts[0]; if (parts.Length > 1) { isDescending = parts[1].ToLower().Contains("esc"); } PropertyInfo prop = tType.GetProperty(propertyName); if (prop == null) { throw new ArgumentException(string.Format("No property '{0}' on type '{1}'", propertyName, tType.Name)); } var funcType = typeof(Func<,>) .MakeGenericType(tType, prop.PropertyType); var lambdaBuilder = typeof(Expression) .GetMethods() .First(x => x.Name == "Lambda" && x.ContainsGenericParameters && x.GetParameters().Length == 2) .MakeGenericMethod(funcType); var parameter = Expression.Parameter(tType); var propExpress = Expression.Property(parameter, prop); var sortLambda = lambdaBuilder .Invoke(null, new object[] { propExpress, new ParameterExpression[] { parameter } }); var sorter = typeof(Queryable) .GetMethods() .FirstOrDefault(x => x.Name == (isDescending ? "OrderByDescending" : "OrderBy") && x.GetParameters().Length == 2) .MakeGenericMethod(new[] { tType, prop.PropertyType }); return (IQueryable<T>)sorter .Invoke(null, new object[] { source, sortLambda }); } return source; }

5 Responses to “ “OrderBy a string in Entity Framework”

Steve says:

October 27, 2012 at 6:01 am

This is good stuff. Is it possible with this to do an order by that is case insensitive?
Samer says:

March 21, 2013 at 3:35 am

Thanks
so good
manit says:

July 3, 2013 at 8:15 am

this is great code

Thank you.
Oguzhan Kahyaoglu says:

August 17, 2013 at 3:15 am

You made my day bro! I have been implementing a entity-independent system and this works like a charm!
drumhacker says:

November 7, 2013 at 8:52 am

Great job, thanks for the help. Will pass this on.

OrderBy a string in Entity Framework

5 Responses to “ “OrderBy a string in Entity Framework”

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