NAME

Text::RecordParser - read record-oriented files

SYNOPSIS

  use Text::RecordParser;
  my $p = Text::RecordParser->new;
  $p->filename('foo.csv');

  # Split records on two newlines
  $p->record_separator("\n\n");

  # Split fields on tabs
  $p->field_separator("\t");

  # Skip lines beginning with hashes
  $p->comment( qr/^#/ );

  # Trim whitespace
  $p->trim(1);

  # Use the fields in the first line as column names
  $p->bind_header;

  # Get a list of the header fields (in order)
  my @columns = $p->field_list;

  # Extract a particular field from the next row
  my ( $name, $age ) = $p->extract( qw[name age] );

  # Return all the fields from the next row
  my @fields = $p->fetchrow_array;

  # Return all the fields from the next row as a hashref
  my $record = $p->fetchrow_hashref;
  print $record->{'name'};

  # Get all data as arrayref of arrayrefs
  my $data = $p->fetchall_arrayref;

  # Get all data as arrayref of hashrefs
  my $data = $p->fetchall_arrayref( { Columns => {} } );

  # Get all data as hashref of hashrefs
  my $data = $p->fetchall_hashref('name');

DESCRIPTION

This module is for reading record-oriented data. The most common example have records separated by newlines and fields separated by commas or tabs, but this module aims to provide a consistent interface for handling sequential records in a file however they may be delimited. Typically this data lists the fields in the first line of the file, in which case you should call bind_header to bind the field name. If the first line contains data, you can still bind your own field names via bind_fields. Either way, you can then use many methods to get at the data as arrays or hashes.

METHODS

new

This is the constructor. It takes a hash of optional arguments. Each argument can also be set through the method of the same name.

  • filename

    The path to the file being read. If the filename is passed and the fh is not, then it will open a filehandle on that file and sets fh accordingly.

  • comment

    A compiled regular expression identifying comment lines that should be skipped.

  • data

    The data to read.

  • fh

    The filehandle of the file to read.

  • field_separator

    The field separator (default is comma).

  • record_separator

    The record separator (default is newline).

  • field_filter

    A callback applied to all the fields as they are read.

  • header_filter

    A callback applied to the column names.

  • trim

    Boolean to enable trimming of leading and trailing whitespace from fields (useful if splitting on whitespace only).

See methods for each argument name for more information.

Alternately, if you supply a single argument to new, it will be treated as the filename argument.

bind_fields

Takes an array of field names and memorizes the field positions for later use. If the input file has no header line but you still wish to retrieve the fields by name (or even if you want to call bind_header and then give your own field names), simply pass in the an array of field names you wish to use.

  $p->bind_fields( qw[ name rank serial_number ] );

bind_header

Takes the fields from the next row under the cursor and assigns the field names to the values. Usually you would call this immediately after opening the file in order to bind the field names in the first row.

  $p->bind_header;
  my $name = $p->extract('name');

comment

Takes a regex to apply to a record to see if it looks like a comment to skip.

  $p->comment( qr/^#/ );  # Perl-style comments
  $p->comment( qr/^--/ ); # SQL-style comments

data

Allows a scalar, scalar reference, glob, array, or array reference as the thing to read instead of a file handle.

  $p->data( $string );
  $p->data( \$string );
  $p->data( @lines );
  $p->data( [ $line1, $line2, $line3] );
  $p->data( IO::File->new('<data') );

It's not advised to pass a filehandle to data as it will read the entire contents of the file rather than one line at a time if you set it via fh.

extract

Extracts a list of fields out of the last row read. The field names must correspond to the field names bound either via bind_fields or bind_header.

  my ( $foo, $bar, $baz ) = $p->extract( qw[ foo bar baz ] );

fetchrow_array

Reads a row from the file and returns an array or array reference of the fields.

  my @values = $p->fetchrow_array;

fetchrow_hashref

Reads a line of the file and returns it as a hash reference. The keys of the hashref are the field names bound via bind_fields or bind_header.

  my $record = $p->fetchrow_hashref;
  print "Name = ", $record->{'name'}, "\n";

fetchall_arrayref

Like DBI's fetchall_arrayref, returns an arrayref of arrayrefs. Also accepts optional "{ Columns => {} }" argument to return an arrayref of hashrefs.

  my $records = $p->fetchall_arrayref;
  for my $record ( @$records ) {
      print "Name = ", $record->[0], "\n";
  }

  my $records = $p->fetchall_arrayref( { Columns => {} } );
  for my $record ( @$records ) {
      print "Name = ", $record->{'name'}, "\n";
  }

fetchall_hashref

Like DBI's fetchall_hashref, this returns a hash reference of hash references. The keys of the top-level hashref are the field values of the field argument you supply. The field name you supply can be a field created by a field_compute.

  my $records = $p->fetchall_hashref('id');
  for my $id ( keys %$records ) {
      my $record = $records->{ $id };
      print "Name = ", $record->{'name'}, "\n";
  }

fh

Gets or sets the filehandle of the file being read.

  open my $fh, "<./data.csv";
  $p->fh( $fh );

field_compute

A callback applied to the fields identified by position (or field name if bind_fields or bind_header was called).

The callback will be passed two arguments:

  1. The current field

  2. A reference to all the other fields, either as an array or hash reference, depending on the method which you called.

If data looks like this:

  parent    children
  Mike      Greg,Peter,Bobby
  Carol     Marcia,Jane,Cindy

You could split the "children" field into an array reference with the values like so:

  $p->field_compute( 'children', sub { [ split /,/, shift() ] } );

The field position or name doesn't actually have to exist, which means you could create new, computed fields on-the-fly. E.g., if you data looks like this:

    1,3,5
    32,4,1
    9,5,4

You could write a field_compute like this:

    $p->field_compute( 3,
        sub {
            my ( $cur, $others ) = @_;
            my $sum;
            $sum += $_ for @$others;
            return $sum;
        }
    );

Field "3" will be created as the sum of the other fields. This allows you to further write:

    my $data = $p->fetchall_arrayref;
    for my $rec ( @$data ) {
        print "$rec->[0] + $rec->[1] + $rec->[2] = $rec->[3]\n";
    }

Prints:

    1 + 3 + 5 = 9
    32 + 4 + 1 = 37
    9 + 5 + 4 = 18

field_filter

A callback which is applied to each field. The callback will be passed the current value of the field. Whatever is passed back will become the new value of the field. Here's an example that capitalizes field values:

  $p->field_filter( sub { $_ = shift; uc(lc($_)) } );

field_list

Returns the fields bound via bind_fields (or bind_header).

  $p->bind_fields( qw[ foo bar baz ] );
  my @fields = $p->field_list;
  print join(', ', @fields); # prints "foo, bar, baz"

field_positions

Returns a hash of the fields and their positions bound via bind_fields (or bind_header).

field_separator

Gets and sets the token to use as the field delimiter. The default is a comma. Regular expressions can be specified using qr//.

  $p->field_separator("\t");     # splits fields on tabs
  $p->field_separator('::');     # splits fields on double colons
  $p->field_separator(qr/\s+/);  # splits fields on whitespace
  my $sep = $p->field_separator; # returns the current separator

filename

Gets or sets the complete path to the file to be read. If a file is already opened, then the handle on it will be closed and a new one opened on the new file.

  $p->filename('/path/to/file.dat');

header_filter

A callback applied to column header names. The callback will be passed the current value of the header. Whatever is returned will become the new value of the header. Here's an example that collapses spaces into a single underscore and lowercases the letters:

  $p->header_filter( sub { $_ = shift; s/\s+/_/g; lc $_ } );

record_separator

Gets and sets the token to use as the record separator. The default is a newline ("\n").

To read a file that looks like this:

  field1
  field2
  field3
  // 
  data1
  data2
  data3
  //

Set the record and field separators like so:

  $p->record_separator("\n//\n");
  $p->field_separator("\n");

trim

Remove leading and trailing whitespace from fields.

  my $trim_value = $p->trim(1);

AUTHOR

Ken Y. Clark <kclark@cpan.org>.

CREDITS

Thanks to the following:

  • Benjamin Tilly

    For Text::xSV, the inspirado for this module

  • Tim Bunce et al.

    For DBI, from which many of the methods were shamelessly stolen

  • Tom Aldcroft

    For contributing code to make it easy to parse whitespace-delimited data

COPYRIGHT

Copyright (c) 2003-4 Ken Y. Clark

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

BUGS

None known. Please use http://rt.cpan.org/ for reporting bugs.