CODEWITHSUNDEEP
c#linq
StrugglingCoder
StrugglingCoder

Reputation: 5011

LINQ Query from one collection to populate the other one

I have a list GroupMembershipValidList that contains objects of type GroupMembershipUploadInput.

This GroupMembershipUploadInput class definition looks like 

   public class GroupMembershipUploadInput
    {
        public string chpt_cd { get; set; }}
        public string cnst_last_nm { get; set; }
        public string appl_src_cd { get; set; }

    }

I have simplified the definition for the sake of simplicity.

Now I have another list _validChapterCodes (public List<ChapterCodeValidationOutput> _validChapterCodes { get; set; })

that contains objects of type 

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

So, What I want to do is .. if the chpt_cd from list A matches list B , then populate the appl_src_cd names from list B to list A objects.

How would I do it in LINQ ?

I tried ...

gmvo.GroupMembershipValidList.GroupMembershipUploadInputList.Where(x => gmvo._validChapterCodes.Contains(x.chpt_cd)).Select(y => y.appl_src_cd);

But I know I am not doing it properly .

Upvotes: 0

Views: 489

Answers (2)

Shyju
Shyju

Reputation: 218702

You can use a LINQ expression.

var a = new List<GroupMembershipUploadInput>
{
    new GroupMembershipUploadInput() {chpt_cd = "A" },
    new GroupMembershipUploadInput() {chpt_cd = "A2"" },
    new GroupMembershipUploadInput() {chpt_cd = "A3" }
};

var b = new List<ChapterCodeValidationOutput>
{
    new ChapterCodeValidationOutput() {chpt_cd = "A", appl_src_cd = "ACode"},
    new ChapterCodeValidationOutput() {chpt_cd = "C2", appl_src_cd = "C22"},
    new ChapterCodeValidationOutput() {chpt_cd = "A3", appl_src_cd = "A33"}
};


var result = a.Select(s => new GroupMembershipUploadInput
{
    chpt_cd = s.chpt_cd,
    appl_src_cd = b.Any(u => u.chpt_cd == s.chpt_cd) ?
                          b.First(v => v.chpt_cd == s.chpt_cd).appl_src_cd:string.Empty
}).ToList();

Assuming a is a collection of GroupMembershipUploadInput and b is a collection of ChapterCodeValidationOutput

Upvotes: 1

Ren&#233; Vogt
Ren&#233; Vogt

Reputation: 43876

LINQ has a functional approach, meaning it's for getting values out of a set of existing values, not for manipulating existing values.

So you can't avoid at least one foreach here. I'd do it like this:

foreach(var chapter in _validChapterCodes)
{
    ChapterCodeValidationOutput output = GroupMembershipValidList.FirstOrDefault(e =>
        e.chpt_cd == chapter.chpt_cd);
    if (input != null) chapter.appl_src_cd = input.appl_src_cd;
}

FirstOrDefault() returns the first element from your input list with a matching chpt_cd or null if there is no matching element.

EDIT: From your question I'm not sure if you wanted it that way or the other way around (what is list A and list B?). So for completeness the other way:

foreach(var input in GroupMembershipValidList)
{
    var chapter = _validChapterCodes.FirstOrDefault(e =>
        e.chpt_cd == input.chpt_cd);
    if (chapter != null) input.appl_src_cd = chapter.appl_src_cd;
}

Upvotes: 1

Related Questions