CODEWITHSUNDEEP
c#wpflinqlist
Sam
Sam

Reputation: 85

Convert ToList() to a list of MyObject

I'm trying to convert a List of MyObject that I'm doing operation on by using LINQ and turning back to a list of MyObject.

public class Part
{
    public string ID { get; set; }
    public string DescFr { get; set; }
    public string DescEng { get; set; }
    public string PartNumber{ get; set; }
    public Part(string strID, string strDescFr, string strDescEng, string strPartNumber) 
    {
        this.ID = strID;
        this.DescFr = strDescfr;
        this.DescEng = strDescEng;
        this.PartNumber= strPartNumber;
    }
}

So in another class I use that class to create a list of Part objects via the database.

List<Part> lstParts = DB.Query.GetParts();

After that I'm grouping them by description

var lstGrouped = lstParts.GroupBy(x => x.DescrFr);

EDIT:

var lstGrouped = lstParts.GroupBy(x => x.PartNumber);

How can I convert back the lstGrouped back to List<Part>? I have tried the ToList() method and cast it to List<Part>, it does not work, giving me an cast error:

enable to cast object of type

Upvotes: 0

Views: 1621

Answers (3)

Sanjay Singh
Sanjay Singh

Reputation: 714

Looks like you want to get distinct items from the list of items. In that case you can either use Distinct method on the original list or you can go with your group approach and do the following -

lstParts.GroupBy(x => x.PartNumber).Select(x=>x.First()).ToList();

Upvotes: 0

BradleyDotNET
BradleyDotNET

Reputation: 61369

Since grouping returns an IEnumerable of IGrouping you can't just transform it back into the sub-list. If you are trying to remove duplicates, just select the first one:

List<Part> finalList = lstGrouped.Select(g => g.First()).ToList();

If you want all the items back (at which point, why did you group them?) then use SelectMany

List<Part> finalList = lstGrouped.SelectMany(g => g).ToList();

Upvotes: 1

Christoph
Christoph

Reputation: 4401

GroupBy returns an IEnumerable<IGrouping<TKey, TSource>>so you are no longer working w/ just a list of TSource (in your case Part), but a list of groupings.

You may want to iterate over the groupings and get the list from each (see How to get values from IGrouping).

Hard to fully answer since I'm not clear on objective (why you would group, just to get the ungrouped list again).

Upvotes: 0

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