C＃，Linq，动态查询：用于过滤存储库外部的动态查询的代码

Question

If you do something like this in your Repository:

IQueryable<CarClass> GetCars(string condition, params object[] values) {
    return db.Cars.Where(condition, values);
}

And you set the condition and values outside of the repository:

string condition = "CarMake == @Make";
object[] values = new string[] { Make = "Ford" };

var result = myRepo.GetCars( condition, values);

How would you be able to sort the result outside of the repository with Dynamic Query?

return View( "myView", result.OrderBy("Price"));

Somehow I am losing the DynamicQuery nature when the data exits from the repository. And yes, I haven't worked out how to return the CarClass type where you would normally do a Select new Carclass { fieldName = m.fieldName, ... }

Answer 1

Dynamic query requires:

• the source be IQueryable<T> (so if it is IEnumerable<T> or similar, just call .AsQueryable() on it)
• an extra dll to be referenced in the code that wants to perform dynamic query
• the appropriate using directives to be in place at the top of the local source file

Check those three, and you should be able to add .Where(condition) , .OrderBy(name) , etc