CODEWITHSUNDEEP
c#linqlistgenerics
user1444433
user1444433

Reputation: 111

Sort dynamic List<T> for a specific property

I have a generic list which I want to order by two properties, priority and then by description to fill a drop down list.

I know that when I now exactly the type of the object list I can do

list = list.Orderby(x=>x.property1).ThenOrderBy(x=>x.property2).

My question is how can I check if the property1 and property2 exist on the object and then sort my list based on those properties.

Upvotes: 1

Views: 1208

Answers (3)

Munam Yousuf
Munam Yousuf

Reputation: 547

well, the way you are trying to do it is a bad idea. Try using if-else or switch case first and then put your code to order them the way you want accordingly.

Upvotes: 0

Xiaoy312
Xiaoy312

Reputation: 14477

You can wrap the selector in a try-catch block :

Func<dynamic, dynamic> DynamicProperty(Func<dynamic, dynamic> selector)
{
    return x =>
    {
        try
        {           
            return selector(x);
        }
        catch (RuntimeBinderException)
        {
            return null;
        }
    };
}

Usage :

var sorted = list
    .OrderBy(DynamicProperty(x => x.property1))
    .ThenBy(DynamicProperty(x => x.property2));

Upvotes: 0

Marc Selis
Marc Selis

Reputation: 833

Because you are using a generic list, the compiler will check that for you.

For example: if you write code like

List<Object> list = new List<Object>();
var newlist = list.Orderby(x=>x.property1).ThenOrderBy(x=>x.property2);

you'll get a compiler error on property1 & property2 because the compiler won't find these properties on the Object type.

If you want to support different types that each should have those 2 properties, the correct way would be to create an interface with those 2 properties, let each of the types you want to support implement that interface and then use a constraint on T like Arturo proposed.

Something like

interface ICanBeSorted
{
   string property1 {get;}
   string property2 {get;
}

public List<T> MySortMethod(List<T> list) where T : ICanBeSorted
{
   return list.OrderBy(x=>x.property1).ThenOrderBy(x=>x.property2);
}

This method will be able to sort all types that implement interface ICanBeSorted.

Upvotes: 2

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