Generic function to evaluate properties dynamically

user_1335792 0
Viewed 48

I have the following classes:

public class Vehicle
{
    public string Name { get; set; }
    public bool CanFly { get; set; }
    public bool CanDive { get; set; }
}

public class Hdd
{
    public string Name { get; set; }
    public bool CanRead { get; set; }
    public bool CanWrite { get; set; }
    public bool CanCopy { get; set; }
}

I want to write one function that can filter for example if a specific car exists (filter by firstOrDefault name) then check the given condition as parameter, for example CanFly or CanDive... etc

so i was thinking of:

public class TestProperties
{
    public bool Check<T>(List<T> items, string name,
        Expression<Func<T, bool>> expression)
    {
        var expr = (MemberExpression)expression.Body;
        var prop = (PropertyInfo)expression.Member;
        //1- Filter items with the given name
        // return false if no records found
        // return false if the condition fails 
    }
}

Then I would call the functions as follow

var myHdds= GetHdd();
var myCars= GetCars();
var CanRead = Check<Hdd>(myHdds,"samsung",x => x.CanRead);
var CanFly = Check<Vehicle>(myCars,"Audi",x => x.CanFly);

How can i implement the Check function?

c#
1 Answers

You are almost there. Try this - 

public bool Check<T>(List<T> items, Expression<Func<T, bool>> expression)
{
    return items.Any(x => expression.Compile()(x));
}

or, 

public bool Check<T>(List<T> items, Func<T, bool> compiledExp)
{
    return items.Any(x => compiledExp(x));
}

and call like this - 

Check<Vehicle>(myCars, x => x.Name == "Audi" && x.CanFly);
Check<Hdd>(myHdds,x => x.Name == "Samsung" &&  x.CanRead);

But now to think of this, you really don't need a method to do that. It is literally one line of code.

Personally I would have preferred an extension method - 

public static bool Check<T>(this List<T> items, Func<T, bool> compiledExp)
{
    return items.Any(x => compiledExp(x));
}

and call like - 

myHdds.Check(x => x.Name == "Samsung" &&  x.CanRead);
user_14769410
Related