Difference from one collection from another collection using Linq

Question

I have two collections. First one is of complex type that contains two string properties

chpt_cd and appl_src_cd

public class ChapterCodeValidationOutput
{
    public string chpt_cd { get; set; }
    public string appl_src_cd { get; set; }
}

And it's get stored in a variable _validChapterCodeLst.

It's sample data may look like :

chpt_cd    aapl_src_cd
-------    -----------

07038      C062
06206      C191

The input to the method that produces the collection is a collection of strings.

List<string> _chapterCodes 

that may contain data like :

'070038'

I want to find the difference between the two collection and put them in two separate lists accordingly.

Whichever is there in the _validChapterCodeLst should be the Valid Output List and it should have two columns likewise

chpt_cd and associated appl_src_cd and the invalid list should contain the difference between _validChapterCodeLst and _chapterCodes input list. And also should contain two columns likewise.

I tried

gmvo._invalidChapterCodes = gmvi._chapterCodes.Except(_validChapterCodeLst.ConvertAll(x => x.chpt_cd.ToString())).ToList();

I tried to convert _validChapterCodeLst to List first and then perform Except.

But that did not work .

Also I do not know how to get the associated appl_src_cd .

Output should be

06206 C191

Answer 1

Except accepts only collections of the same type. However, you can try this (I used HashSet here for better performance):

var _chapterCodesHashSet = new HashSet<string>(_chapterCodes);
var _invalidChapterCodes = _validChapterCodeLst.Where(item => !_chapterCodesHashSet.Contains(item.chpt_cd)).ToList();

Answer 2

I used where

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<ChapterCodeValidationOutput> _validChapterCodeLst = new List<ChapterCodeValidationOutput>() {
                new ChapterCodeValidationOutput() { chpt_cd =  "07038", appl_src_cd = "C062"},
                new ChapterCodeValidationOutput() { chpt_cd =  "06206", appl_src_cd = "C191"}
            };
            List<string> _chapterCodes = new List<string>() { "07038" };
            var results = _validChapterCodeLst.Where(x => !_chapterCodes.Contains(x.chpt_cd)).Select(y => new { chpt_cd = y.chpt_cd, appl_src_cd = y.appl_src_cd}).ToList();
        }
    }
    public class ChapterCodeValidationOutput
    {
        public string chpt_cd { get; set; }
        public string appl_src_cd { get; set; }
    }
}