Linq to Entities Filtering an Entity Dynamic/Strongly Typed

问题

I am binding a Winforms Grid to an entity. (For reasons I won't go into here it must be bound to the entity, not the result a query) The code is as follows:

grid.DataSource = myEntities.entityName.Where("it.field = " & field)

It works, but it obviously isn't strongly typed. Is there a way to define the Where clause of an entity using a strongly typed notation?

回答1:

Have you tried to use a lambda expression?

grid.DataSource = myEntities.Customers.Where(c => c.Name == "Bob");

or in VB:

grid.DataSource = myEntities.Customers.Where(Function(c) c.Name = "Bob")

If it has to be dynamic then you might want to look at building a custom Expression Tree. For a tutorial on the basics of Expression Trees see this blog http://blogs.msdn.com/charlie/archive/2008/01/31/expression-tree-basics.aspx

This blog shows a good example of sorting. http://weblogs.asp.net/davidfowler/archive/2008/12/11/dynamic-sorting-with-linq.aspx

来源：https://stackoverflow.com/questions/784363/linq-to-entities-filtering-an-entity-dynamic-strongly-typed