C#•2y ago

How to add additional headers/columns to CSV file?

Using CSVHelper to manipulate a CSV file but when I try to add additional columns of information I get the error, I thought this would be really simple to add.

Error: Header with name 'Payee_Country'[0] was not found.
Header with name 'Payer_Address1'[0] was not found.
Header with name 'Payer_Address2'[0] was not found.
Header with name 'Payer_City'[0] was not found.
Header with name 'Payer_State' [0] was not found.
Header with name 'Payer_Zip'[0] was not found.
Header with name 'Payer_Country'[0] was not found.

Error: Header with name 'Payee_Country'[0] was not found.
Header with name 'Payer_Address1'[0] was not found.
Header with name 'Payer_Address2'[0] was not found.
Header with name 'Payer_City'[0] was not found.
Header with name 'Payer_State' [0] was not found.
Header with name 'Payer_Zip'[0] was not found.
Header with name 'Payer_Country'[0] was not found.

Error: Header with name 'Payee_Country'[0] was not found.
Header with name 'Payer_Address1'[0] was not found.
Header with name 'Payer_Address2'[0] was not found.
Header with name 'Payer_City'[0] was not found.
Header with name 'Payer_State' [0] was not found.
Header with name 'Payer_Zip'[0] was not found.
Header with name 'Payer_Country'[0] was not found.

Error: Header with name 'Payee_Country'[0] was not found.
Header with name 'Payer_Address1'[0] was not found.
Header with name 'Payer_Address2'[0] was not found.
Header with name 'Payer_City'[0] was not found.
Header with name 'Payer_State' [0] was not found.
Header with name 'Payer_Zip'[0] was not found.
Header with name 'Payer_Country'[0] was not found.

code.txt9.53KB

Pobiega•3/13/24, 6:51 PM

CSVHelper doesnt by default allow missing headers

Pobiega•3/13/24, 6:53 PM

but if you create a config and set it up correctly, it allows it just fine

Pobiega•3/13/24, 6:53 PM

var config = new CsvConfiguration(CultureInfo.InvariantCulture) { HeaderValidated = null, MissingFieldFound = null };

using (var reader = new StreamReader("data.csv"))
using (var csv = new CsvReader(reader, config))
{
    list = csv.GetRecords<T>().ToList();
}

var config = new CsvConfiguration(CultureInfo.InvariantCulture) { HeaderValidated = null, MissingFieldFound = null };

using (var reader = new StreamReader("data.csv"))
using (var csv = new CsvReader(reader, config))
{
    list = csv.GetRecords<T>().ToList();
}

Pobiega•3/13/24, 6:53 PM

note how I set both HeaderValidatedHeaderValidated and MissingFieldFoundMissingFieldFound to null here

Pobiega•3/13/24, 6:54 PM

this allows me to parse a file that doesnt match my record class.

Pobiega•3/13/24, 6:54 PM

HOWEVER

Pobiega•3/13/24, 6:54 PM

this is a bad idea

Pobiega•3/13/24, 6:54 PM

If you know the CSV file doesnt contain these values and you want to add them, you should have two models

Pobiega•3/13/24, 6:54 PM

one without and one with the new fields

Pobiega•3/13/24, 6:55 PM

then simply read the values, then use .Select.Select or some other method to turn your objects from A into B, adding the data as needed, then save the list of Bs

PPobiega then simply read the values, then use `.Select` or some other method to turn you...

SCOLANATOROP•3/13/24, 7:02 PM

Could you show me how to do that?

SCOLANATOROP•3/13/24, 7:02 PM

I'm struggling a bit here

Pobiega•3/13/24, 7:04 PM

List<OriginalRecord> list;

var config = new CsvConfiguration(CultureInfo.InvariantCulture) { HeaderValidated = null, MissingFieldFound = null };

using (var reader = new StreamReader("data.csv"))
using (var csv = new CsvReader(reader, config))
{
    list = csv.GetRecords<OriginalRecord>().ToList();
}

var newList = list.Select(x => new UpdatedRecord()
{
    Id = x.Id, Name = x.Name, Time = x.Time, RandomNumber = Random.Shared.Next(100),
}).ToList();

// newList now contains the updated list

List<OriginalRecord> list;

var config = new CsvConfiguration(CultureInfo.InvariantCulture) { HeaderValidated = null, MissingFieldFound = null };

using (var reader = new StreamReader("data.csv"))
using (var csv = new CsvReader(reader, config))
{
    list = csv.GetRecords<OriginalRecord>().ToList();
}

var newList = list.Select(x => new UpdatedRecord()
{
    Id = x.Id, Name = x.Name, Time = x.Time, RandomNumber = Random.Shared.Next(100),
}).ToList();

// newList now contains the updated list

SCOLANATOROP•3/13/24, 7:17 PM

Thank you, I'm not quite sure how to add this into my code but I'll give it a go!

Pobiega•3/13/24, 7:18 PM

step 1 is to just make a record type that has only the headers and values that are in your current csv file

Pobiega•3/13/24, 7:18 PM

then you make the second record type that has the ones you want in your output

Pobiega•3/13/24, 7:19 PM

then its as simple as making a method that converts from type 1 into type 2, passing that method to .Select.Select (I used a lambda, but you can pass a real method too) and you're pretty much done

SCOLANATOROP•3/13/24, 9:33 PM

Could you help me put this into my code? I'm banging my head trying to do this, it's been a while since I was last working on C# and this code

Pobiega•3/13/24, 9:34 PM

This is very basic stuff, except maybe the .Select.Select call but I can help you with that

Pobiega•3/13/24, 9:35 PM

have you made the two models and the mapping method?

Pobiega•3/13/24, 9:44 PM

@SCOLANATOR ?

SCOLANATOROP•3/14/24, 8:09 PM

@Pobiega Sorry for the delayed response, had something come up. This was what i've put together so far but there's an issue with line 188

SCOLANATOROP•3/14/24, 8:09 PM

code.txt11.9KB

How to add additional headers/columns to CSV file?

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