How to combine two c# objects using Linq

Question

I am trying to combine two LIKE objects together and remove duplicates.

Here is my object [simple]

public class LabelItem
{
    public string LabelName { get; set; }
    public string LabelValue { get; set; }
}

my data call returns the same object type

public static List<LabelItem> ReturnControlLabelList(Enums.LanguageType languageType, string labelList = "")

I pass this to the method

string[] LABELLIST = new string[] { "foxLabel", "commonLabel" };
var helper = new LabelHelper(, LABELLIST);

this is where I get null

    public LabelHelper(Enums.LanguageType languageType, string[] labelListName)
    {
        if (labelListName != null)
        {
            List<LabelItem> labels = new List<LabelItem>();
            this.LabelList = new List<LabelItem>();

            foreach (var name in labelListName)
            {
                labels = DBCommon.ReturnControlLabelList(languageType, name);
                this.LabelList.Concat(labels).Distinct().ToList();
            }

        }
        else
        {
            this.LabelList = null;
        }

    }

public List<LabelItem> LabelList { get; private set; }

The concat is not working. I keep getting count 0 for labels and I can see the returns come back with 275 and 125 in the for loop.

Thanks in advance for the help.

Still having an issue

I want to use the suggestion from below but am still struggling.

The string[] passed in will get two lists of labelitems that are not unique when joined together in the loop. I need the distinct of the multiple lists returned in this.LabelList.

I got it to work with this but...I'm sure it's crazy inefficient.

Thanks for the help.

             this.LabelList = new List<LabelItem>();

            foreach (var name in labelListName)
            {
                var ret =  DBCommon.ReturnControlLabelList(languageType, name);
                this.LabelList = this.LabelList.Concat(ret).Distinct().ToList();             
            }

            var distinctList = this.LabelList.GroupBy(x => new  { x.LabelName, x.LabelValue })
                 .Select(x => x.FirstOrDefault());

            this.LabelList = new List<LabelItem>();

            foreach (var item in distinctList)
            {
                this.LabelList.Add(item);
                Debug.WriteLine(item.LabelName + ' '  + item.LabelValue);
            }

        }

MarcinJuraszek · Accepted Answer · 2015-12-07 22:25:03Z

8

this.LabelList.Concat(labels).Distinct().ToList(); without assigning it to something doesn't make much sense. LINQ query does not modify the source collection, it returns a new one, so you'd have to assign it back to this.LabelList if you want it to get updated:

this.LabelList = this.LabelList.Concat(labels).Distinct().ToList();

You should be aware, that it's highly inefficient solution, and you should go with something based on SelectMany:

this.LabelList
    = labelListName.SelectMany(name => DBCommon.ReturnControlLabelList(languageType, name)
                   .Distinct()
                   .ToList();

edited Dec 7, 2015 at 22:25

answered Dec 7, 2015 at 22:04

MarcinJuraszek

126k15 gold badges200 silver badges267 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Chris · Accepted Answer · 2015-12-07 22:05:06Z

1

Concat and most other linq methods return an IEnumerable which you then need to do something with. It will not change your existing list so you need to just assign it with:

this.LabelList = this.LabelList.Concat(labels).Distinct().ToList();

answered Dec 7, 2015 at 22:05

Chris

27.7k7 gold badges77 silver badges94 bronze badges

Collectives™ on Stack Overflow

How to combine two c# objects using Linq

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related