MVC LINQ dynamic orderBy getting column type

Question

I am trying to dynamically order a list of products.

Product:
price (int)
name (string)

So far I have managed to get the following:

string columnToOrderBy = "price";
ParameterExpression param = Expression.Parameter(typeof(Product), "p");
var ordering = Expression.Lambda<Func<Product, double>>(Expression.Property(param, columnToOrderBy), param);

this works for ordering by price, however it won't work when ordering by name because of the column type.

Expression.Lambda<Func<Product, double>>

Is there anyway to get the type of a column to set it in the Func method?

Answer 1

Take a look at Dynamic LINQ, Scott Gu did a great post on it here http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx

It makes it as easy as this

query = query.OrderBy(columnName);

or

//orderby descending
query = query.OrderBy(columnName + " DESC");

There's no need to mess around with manually manipulating expression trees when you don't have to. Using dynamic LINQ will make your code easier to understand and maintain.

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Edit

You can now install this as a Nuget package, but none of them seem to be from an official source (at the time of writing).

Here's a vanilla package containing the code that Scott Gu presented.

Here's a branch of Scott's code that has been expanded to include more features. It appears to be under active development, and looks quite interesting.

Answer 2

1. PM> Install-Package System.Linq.Dynamic

2. query = query.OrderBy(columnName);