How do I convert list<string> to ilist<class> in C#?

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Hi,

I am getting error while converting List to IList. How can I solve this?

What I have tried:

private IList<OrganizationItemDetails> _orgLevel3;
List<OrganizationItemDetails> orgLevel3 = await OrganisationService.GetListOfOrgDetails(3);
 _orgLevel3 = orgLevel3.Select(x => x.EntityCode).ToList();

This line

C#

_orgLevel3 = orgLevel3.Select(x => x.EntityCode).ToList();

I am getting error like cannot implicitly convert type List<string> to IList

Posted 10-Jul-23 19:40pm

Rajesh Kumar 2013

Updated 10-Jul-23 20:15pm

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OriginalGriff · Accepted Answer · 2023-07-10T20:15:00

Solution 1

The problem isn't the List / IList implicit cast, that works as you would expect:

C#

List<string> myList = new List<string>();
IList<string> myIlist = myList;

The problem is that your IList type doesn't match the List type the Select returns:

C#

private IList<OrganizationItemDetails> _orgLevel3;

Check the type of x.EntityCode and you'll probably find it's a string from yoru question title.

Easy way to check:

C#

var collection = orgLevel3.Select(x => x.EntityCode).ToList();
_orgLevel3 = collection;

If you hover over collection in VS, it'll tell you what type it expands to.

Posted 10-Jul-23 20:15pm

OriginalGriff

Comments

Rajesh Kumar 2013 11-Jul-23 2:31am

'collection' is List<string>. Then how can assign 'collection' value to IList<organizationitemdetails> _orgLevel3's EntityCode ?

OriginalGriff 11-Jul-23 2:49am

You can't - because there is no conversion from a string to a OrganizationItemDetails. What you need to do is work out how EntityCode relates to OrganizationItemDetails and modify your Select to perform the conversion.
You can't even cast from a collections of a derived class to a collection of it's base class:

        public class baseClass { }
        public class derivedClass : baseClass { }
...
            List<baseClass> listBaseClass = new List<baseClass>();
            List<derivedClass> listDerivedClass = new List<derivedClass>();
            listBaseClass = listDerivedClass;                    // ERROR
            listBaseClass = (List<baseClass>)listDerivedClass;   // ERROR

The only way to do that is to iterate the list and cast the elements to a new collection!

Rajesh Kumar 2013 11-Jul-23 3:21am

I have written like this _orgLevel3 = orgLevel3.Where(x => x.EntityCode != "").ToList(); Is it okay?

OriginalGriff 11-Jul-23 3:36am

Should be.