C# Linq All Condition

Question

I have a list of codes as follows

public Code{
    int id;
    string Description;
}

List<Code> AllCodes;

I have a list of selected codes from a different source.

var relatedCodes = //gets the list of int 'id's from a different source.

Using linq , I need to join AllCodes and relatedCodes so that the resultant list contains all the Code elements of the given id s. It is known that all the int values in relatedCodes are valid id s in AllCodes . [ relatedCodes is an int array]

result = //how to write the linq expression?

I was trying something like this but it throws error

result = AllCodes.All(x => x.Code==relatedCodes);

Answer 1

List<Code> result = AllCodes.Where(x => relatedCodes.Contains(x.id)).ToList();

Answer 2

First of all there is nothing to do with Join . Question is briefly How can I get the Codes of which relatedCodes contains the id? . You can use Where to filter your list.

var result = AllCodes.Where( c=> relatedCodes.Contains(c.id));

Answer 3

EDIT: Since relatedCodes is of type int[] (I used an array of type Code ) the solution looks slightly different, but not by too much:

var relatedCodes = new int[2] { 2, 4 };

var joinedCodes = from ac in AllCodes
                  join rc in relatedCodes on ac.Id equals rc
                  select ac;

ORIGINAL answer

One possibility is to use join:

void Main()
{
    var AllCodes = new List<Code>() 
    {
        new Code() {Id = 1, Description="Foo1"},
        new Code() {Id = 2, Description="Bar2"},
        new Code() {Id = 3, Description="Foo3"},
        new Code() {Id = 4, Description="Bar4"}
    };

    var relatedCodes = new Code[2] 
    {
        new Code() {Id = 2, Description="Bar2"},
        new Code() {Id = 4, Description="Bar4"}
    };

    var joinedCodes = from ac in AllCodes
                      join rc in relatedCodes on ac.Id equals rc.Id
                      select ac;
    joinedCodes.Dump();
}

// Define other methods and classes here
public class Code{
    public int Id { get; set; }
    public string Description { get; set; }
}

Ouput: