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c#asp.net-mvclinqdynamic-typing
kiwijus
kiwijus

Reputation: 1237

MVC LINQ dynamic orderBy getting column type

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?

Upvotes: 2

Views: 4345

Answers (2)

Doctor Jones
Doctor Jones

Reputation: 21664

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.

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.

Upvotes: 5

Yini
Yini

Reputation: 711

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

  2. query = query.OrderBy(columnName);

Upvotes: 0

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