i have next class

public class MainClass
{
   public ClassA someProp { get; set; }
}

public class ClassA
{
   public virtual Type Types => Type.None;
}

public class ClassB:ClassA
{
   public override Type Types => Type.Default;
        
   public string FieldName { get; set; }
}

i want get FieldName from ClassB

var result = entities.Where(x => x.someProp != null).Select(x => x.someProp).ToList();

and than i get

var fields = (from ClassB in result select t.FieldName).ToList();

what is better way get FieldName from ClassB

I don't think this is the best solution. Maybe there are some best practices for my question?

CodePudding user response：

I've to filter the entities and get only those that are ClassB, then read the property as usual.

var values = entities
      .Select(mainClass => mainClass.SomeProp)
      .OfType<ClassB>()
      .Select(classB => classB.FieldName)

CodePudding user response：

You can try this:

var fields = entities
    .Where(item => item.someProp is ClassB)
    .Select(item => item.someProp)
    .Cast<ClassB>()
    .Select(item => item.FieldName).ToList();

CodePudding user response：

This is a shorter way, you can try cast ClassB from someProp:

var result = lst.Where(x => x.someProp != null).Select(x => (ClassB)x.someProp).Select(x => x.FieldName).ToList();