how to convert foreach loop to lambda expression in c#

Question

foreach (IndexingField field in document.IndexingFields)
{
    if (field.TableColumn.ToLower() == "esig"&& field.Data != null && !string.IsNullOrEmpty(field.Data.ToString()) && field.Data.ToString() != "N")
    {                               
        EsigBase64Value = field.Data.ToString();
        field.Data = "Y";                                
    }                    
}

this is for each loop i am using , i would like to convert this for each loop to lambda expression ,please help me on this

Why? What is the actual question? You can convert the contents of a loop into a lambda and call it but that lambda will look no different from a method or even a local method. If you want to clean up your code, extract the loop block's code into a separate method — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Jul 1, 2021 at 7:47
What is EsigBase64Value? The way the code is written, it will only contain the contents of the last field after the loop. This is almost certainly a bug — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Jul 1, 2021 at 7:48
Related. TLDR; you can use ToList().ForEach() combo or create extension method yourself. — Sinatr
– Sinatr, Commented Jul 1, 2021 at 7:50
What is field.Data's type? Why the calls to ToString()? field.Data.ToString() != "N" will only work if Data is already a string. The if condition could be simplified a lot — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Jul 1, 2021 at 7:52

Marc Gravell · Accepted Answer · 2021-07-01 07:46:32Z

5

Loops and lambda expressions are different things with different purposes. There is no lambda expression that correlates directly with this intent, and regular LINQ methods like Select are intended to perform projections (creating new data), not mutations (changing existing data).

In short: leave the code alone - it is fine as-is. My main observation would be what the value of EsigBase64Value is intended to be when there are zero or multiple records that match the if test. You might also want to hoist the field.Data.ToString() value, so it only happens once:

var data = field.Data.ToString();
if (...)
{

}

(using data in each place where field.Data.ToString() appears)

and maybe use a case-insensitive overload of string.Equals rather than field.TableColumn.ToLower() == "esig"

answered Jul 1, 2021 at 7:46

Marc Gravell

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Comments

H.Sarxha · Accepted Answer · 2021-07-01 09:56:28Z

1

You can use .Where

var field = document.IndexingFields.Where(f => f.TableColumn.ToLower() == "esig" && f.Data != null && !string.IsNullOrEmpty(f.Data.ToString()) && f.Data.ToString() != "N").FirstOrDefault();

And after that you can check with if condition

if (field != null)
 {
   EsigBase64Value = field.Data.ToString();
    field.Data = "Y";    
 }

edited Jul 1, 2021 at 9:56

answered Jul 1, 2021 at 8:36

H.Sarxha

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6 Comments

chandra Over a year ago

i have tried above statements.in field we are not getting data property

H.Sarxha Over a year ago

@chandra you can try to reduce the checking for null or empty value, some of those are not necessary, for example !string.IsNullOrEmpty(f.Data.ToString())

chandra Over a year ago

see i am not getting issue with those conditions, we are getting data in field which is of var data type .in that field i am not getting property which is field.data

H.Sarxha Over a year ago

@chandra did u use .FirstOrDefault() ?

chandra Over a year ago

thank you so much it is working after using first or default

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