Updating an existing List using Linq in C#

Question

I have a list and data as follows.

public class Test
{
 public int Id {get;set;}
 public string Name {get;set;}
 public string Quality {get;set;}
}

Test test = new Test();
//db call to get test data
//test = [{1,'ABC','Good'},{2,'GEF','Bad'}]

I have to modify the list such that Name should be only the first 2 characters and Quality should be the first letter.

Expected Output:

//test = [{1,'A','G'},{2,'GE','B'}]

I tried to achieve with Linq foreach as follows. But I am not sure to write conditional statements inside forloop within Linq which resulted in error.

test.ForEach(x=> return x.Take(1))

You could override ToString function inside Test class, In that function you could substring all fields as u wish, and return a string. — Bartosz
– Bartosz, Commented Feb 8, 2022 at 10:55

Tim Schmelter · Accepted Answer · 2022-02-08 10:55:27Z

3

List.ForEach is not LINQ though

test.ForEach(t => { t.Name = t.Name.Length > 2 ? t.Name.Remove(2) : t.Name; t.Quality = t.Quality.Length > 1 ? t.Quality.Remove(1) : t.Quality; });

Better would be to simply call a method that does this.

test.ForEach(Modify);

private static void Modify(Test t)
{
    // ,,,
}

answered Feb 8, 2022 at 10:55

Tim Schmelter

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Comments

Selim Yildiz · Accepted Answer · 2022-02-08 11:09:10Z

1

You can use simply use String.Substring as follows:

test.ForEach(s =>
{
    s.Name = s.Name.Substring(0, 2);
    s.Quality = s.Quality.Substring(0, 1);
});

Thanks, @Tim for pointing out that if Name or Quality is short then this code throws an exception. See Problem with Substring() - ArgumentOutOfRangeException for the possible solutions for that.

edited Feb 8, 2022 at 11:09

answered Feb 8, 2022 at 10:59

Selim Yildiz

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