How do I read only a set number of fields from a csv using the FileHelpers library?

Question

I've got an application on my hands that uses the FileHelpers library to process csv files.

In the past, the input csv files always had the same structure, 5 comma-separated fields for a record, then a new line to delimit records.

Recently, however, I started receiving csv files that have more than five records per line, and, apparently, the class that is currently used for csv parsing isn't applicable for these lines. The thing is, I still only need the first five fields, which are still supplied in he same order.

Is there any way to read the first five fields with FileHelpers, and ignore any other data until a newline?

The class currently used for parsing:

[IgnoreEmptyLines()]
[DelimitedRecord(";")]
public sealed class SemicolonsRow
{
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String LastName;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String Name;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String MidName;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String BirthDate;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String BirthPlace;
}

score 5 · Answer 1 · answered Mar 26 '15 at 15:11

5

Using FileHelper you can add this variable as your last one:

public string[] FunkyNewField;

If you have FieldOrder defined then add it like this:

[FieldOrder(n)]
public string[] FunkyNewField;

where n = number after your last specified order number.

This will contain all the extra columns in your file that you didn't want to use.

answered Mar 26 '15 at 15:11

Sibongiseni Buthelezi

51
1
1

This solves ignoring the not required columns( any numbers). I tried with List by trial and error and felt annoyed :) thanks for sharing. – Muthukumar Palaniappan Oct 05 '16 at 01:42

Arj · Accepted Answer · 2014-01-31T11:50:39.717

2

The fact that the number of columns is causing a problem would suggest that your design is wrong.

I recently used 'A Fast CSV Reader' to do some CSV parsing and it works absolutely brilliantly. You can index the columns in a simple for loop, so if you only want that first 5 columns, you can do something like this:

CsvReader csv = new CsvReader(new StreamReader(fileName), true);

// Iterating LINES
while (csv.ReadNextRecord())
{
    // Iterating COLUMNS on current line
    for (int i = 0; i < 5; i++)
    {
        string value = csv[i];
        // do stuff with value
    }
}

edited Jan 31 '14 at 11:50

answered Aug 03 '12 at 09:15

Arj

1,981
4
25
45

Thank you for the suggestion, Fast CSV Reader works fine. I was just reluctant to throw out FileHelpers, cause that code was there long before my time. – sdds Aug 03 '12 at 14:17

score 2 · Answer 3 · answered Aug 03 '12 at 18:36

A simple solution can be to add some private dummy fields (as optionals) that will get the values

[IgnoreEmptyLines()]
[DelimitedRecord(";")]
public sealed class SemicolonsRow
{
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String LastName;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String Name;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String MidName;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    public String BirthDate;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    private String DummyField1;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    private String DummyField2;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    private String DummyField3;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    private String DummyField4;

    [FieldOptional()]
    [FieldQuoted('"', QuoteMode.OptionalForRead, MultilineMode.AllowForRead)]
    private String DummyField5;
}

Great trick! Doesn't seem to be documented anywhere, but I've seen others mention this too. — Ralph Willgoss, Nov 12 '12 at 10:44

How do I read only a set number of fields from a csv using the FileHelpers library?

3 Answers3