CODEWITHSUNDEEP
csvhelper
katanisk8
katanisk8

Reputation: 1

How to read first and last row using CsvHelper?

I need validate date range between first and last row in csv file.

How to read first and last row using CsvHelper without reading all lines?

Regards

Upvotes: 0

Views: 1114

Answers (2)

katanisk8
katanisk8

Reputation: 1

I solved my problem.

I read the first line using CsvReader and standard GetRecord method.

The last line I read as a string using ReverseLineReader from @Jon Skeet answer.

Then I put this string in StringReader and next to CsvReader, then read the record using GetRecord method.

I hope someone will find it useful someday.

Regards katanisk8

Upvotes: 0

David Specht
David Specht

Reputation: 9074

I don't know that it is possible to only read the first and the last lines. You can at least limit the amount of data you bring into memory.

void Main()
{
    using (var reader = new StringReader("Id,Name,RowDate\n1,First,7/1/2022\n2,Middle,7/15/2022\n3,Last,7/31/2022"))
    using (var csv = new CsvReader(reader, CultureInfo.InvariantCulture))
    {
        DateTime first;
        DateTime last = DateTime.MinValue;

        csv.Read();
        csv.ReadHeader();
        
        csv.Read();
        first = csv.GetField<DateTime>("RowDate");  
       
        while (csv.Read())  
        {
            last = csv.GetField<DateTime>("RowDate");   
        }

        Console.WriteLine($"First: {first}");
        Console.WriteLine($"Last: {last}");
    }
}

public class Foo
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime RowDate { get; set; }
}

Upvotes: 3

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