CODEWITHSUNDEEP
c#linqc#-4.0multiple-columns
Furkan Gözükara
Furkan Gözükara

Reputation: 23830

How to select multiple columns from dataset into a string list with LinQ

Okay now this below is working

     List<string> lstKnownMoves = dsAttacksTemp.Tables[0].Rows.
Cast<DataRow>().Select(r => r["Column1"].ToString()).ToList();

But i want to make it work like below and not working

     List<string> lstKnownMoves = dsAttacksTemp.Tables[0].Rows.
Cast<DataRow>().Select(r => r["Column1"].ToString(),r => r["Column2"].ToString(),r => r["Column3"].ToString()).ToList();

So instead of 1 dataset datarow column, i want to add multiple columns into the list. How can i do that ?

Upvotes: 3

Views: 11320

Answers (3)

moribvndvs
moribvndvs

Reputation: 42497

Well, assuming you want to be able to access each column individually, you'd want to return an array of strings.

 List<string[]> lstKnownMoves = dsAttacksTemp.Tables[0].Rows
                          .Cast<DataRow>().Select(r => new[] 
                               { 
                                  r["Column1"].ToString(),  
                                  r["Column2"].ToString(), 
                                  r["Column3"].ToString() 
                               }).ToList();

Then for each row, you can get the string value of a column by index:

 foreach(var item in lstKnownMoves) 
      Console.WriteLine("Column1: {0} Column2: {1} Column3: {2}", item);

If you want basically a map of columns, and would rather not create a class to act as a tuple as in the selected answer, you can use List<dynamic>:

 List<dynamic> lstKnownMoves = dsAttacksTemp.Tables[0].Rows
                          .Cast<DataRow>().Select(r => new 
                               { 
                                  Column1 = r["Column1"].ToString(),  
                                  Column2 = r["Column2"].ToString(), 
                                  Column3 = r["Column3"].ToString() 
                               }).ToList<dynamic>();

 foreach(var item in lstKnownMoves) 
      Console.WriteLine("Column1: {0} Column2: {1} Column3: {2}", 
          item.Column1, item.Column2, item.Column3);

Upvotes: 1

SWeko
SWeko

Reputation: 30892

You could use SelectMany if you just to dump the contents of the fields into a list.

List<string> lstKnownMoves = dsAttacksTemp.Tables[0].Rows
 .Cast<DataRow>()
 .SelectMany(r => new string[]{
                    r["Column1"].ToString(),
                    r["Column2"].ToString(),
                    r["Column3"].ToString()})
 .ToList();

If however, you want to extract the fields into another object, you could do something like:

class KnownMove {
   public string Column1 {get; set;}
   public string Column2 {get; set;}
   public string Column3 {get; set;}
}

List<KnownMove > lstKnownMoves = dsAttacksTemp.Tables[0].Rows
 .Cast<DataRow>()
 .SelectMany(r => new KnownMove{
                    Column1 = r["Column1"].ToString(),
                    Column2 = r["Column2"].ToString(),
                    Column3 = r["Column3"].ToString()})
 .ToList();

Upvotes: 4

Bazzz
Bazzz

Reputation: 26922

I assume you want a list of an object with several string properties instead of a list of string arrays.

List<object> lstKnownMoves = dsAttacksTemp.Tables[0].Rows.
Cast<DataRow>().Select(r => new { 
 Col1 = r["Column1"].ToString(), 
 Col2 = r["Column2"].ToString(), 
 Col3 = r["Column3"].ToString()
}).ToList();

This way you'd get a List<T> where T is an anonymous object with 3 string properties, namely Col1, Col2 and Col3. I guess this is what you are asking for.

Upvotes: 1

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