How to get first object out from List<Object> using Linq

Question

I have below code in c# 4.0.

//Dictionary object with Key as string and Value as List of Component type object
Dictionary>         


        

Answer 1

I do so.

List<Object> list = new List<Object>();

if(list.Count>0){
  Object obj = list[0];
}

Answer 2

Try this to get all the list at first, then your desired element (say the First in your case):

var desiredElementCompoundValueList = new List<YourType>();
dic.Values.ToList().ForEach( elem => 
{
   desiredElementCompoundValue.Add(elem.ComponentValue("Dep"));
});
var x = desiredElementCompoundValueList.FirstOrDefault();

To get directly the first element value without a lot of foreach iteration and variable assignment:

var desiredCompoundValue = dic.Values.ToList().Select( elem => elem.CompoundValue("Dep")).FirstOrDefault();

See the difference between the two approaches: in the first one you get the list through a ForEach, then your element. In the second you can get your value in a straight way.

Same result, different computation ;)

Answer 3

You can do

Component depCountry = lstComp
                       .Select(x => x.ComponentValue("Dep"))
                       .FirstOrDefault();

Alternatively if you are wanting this for the entire dictionary of values, you can even tie it back to the key

var newDictionary = dic.Select(x => new 
            {
               Key = x.Key,
               Value = x.Value.Select( y => 
                      {
                          depCountry = y.ComponentValue("Dep")
                      }).FirstOrDefault()
             }
             .Where(x => x.Value != null)
             .ToDictionary(x => x.Key, x => x.Value());

This will give you a new dictionary. You can access the values

var myTest = newDictionary[key1].depCountry     

Answer 4

I would to it like this:

//Dictionary object with Key as string and Value as List of Component type object
Dictionary<String, List<Component>> dic = new Dictionary<String, List<Component>>();

//from each element of the dictionary select first component if any
IEnumerable<Component> components = dic.Where(kvp => kvp.Value.Any()).Select(kvp => (kvp.Value.First() as Component).ComponentValue("Dep"));

but only if it is sure that list contains only objects of Component class or children