| Text::RecordParser - read record-oriented files |
Text::RecordParser - read record-oriented files
This documentation refers to version 1.2.1.
use Text::RecordParser;
# use default record (\n) and field (,) separators my $p = Text::RecordParser->new( $file );
# or be explicit
my $p = Text::RecordParser->new({
filename => $file,
field_separator => "\t",
});
$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;
# Define a field alias $p->set_field_alias( name => 'handle' );
# Return all the fields from the next row as a hashref
my $record = $p->fetchrow_hashref;
print $record->{'name'};
# or
print $record->{'handle'};
# Return the record as an object with fields as accessors my $object = $p->fetchrow_object; print $object->name; # or $object->handle;
# 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');
This module is for reading record-oriented data in a delimited text
file. 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 (or not, and it will be called implicitly). 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.
This is the object constructor. It takes a hash (or hashref) of arguments. Each argument can also be set through the method of the same name.
fh
accordingly.
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.
$p->bind_fields( qw[ name rank serial_number ] );
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.
Pass in an empty array reference to unset:
$p->bind_field( [] ); # unsets fields
$p->bind_header;
my $name = $p->extract('name');
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->comment( qr/^#/ ); # Perl-style comments $p->comment( qr/^--/ ); # SQL-style comments
Takes a regex to apply to a record to see if it looks like a comment to skip.
$p->data( $string );
$p->data( \$string );
$p->data( @lines );
$p->data( [$line1, $line2, $line3] );
$p->data( IO::File->new('<data') );
Allows a scalar, scalar reference, glob, array, or array reference as the thing to read instead of a file handle.
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.
my ( $foo, $bar, $baz ) = $p->extract( qw[ foo bar baz ] );
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 @values = $p->fetchrow_array;
Reads a row from the file and returns an array or array reference of the fields.
my $record = $p->fetchrow_hashref;
print "Name = ", $record->{'name'}, "\n";
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. If you do not bind fields prior to calling this method,
the bind_header method will be implicitly called for you.
while ( my $object = $p->fetchrow_object ) {
my $id = $object->id;
my $name = $object->naem; # <-- this will throw a runtime error
}
This will return the next data record as a Text::RecordParser::Object object that has read-only accessor methods of the field names and any aliases. This allows you to enforce field names, further helping ensure that your code is reading the input file correctly. That is, if you are using the ``fetchrow_hashref'' method to read each line, you may misspell the hash key and introduce a bug in your code. With this method, Perl will throw an error if you attempt to read a field not defined in the file's headers. Additionally, any defined field aliases will be created as additional accessor methods.
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";
}
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_hashref('id');
for my $id ( keys %$records ) {
my $record = $records->{ $id };
print "Name = ", $record->{'name'}, "\n";
}
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.
open my $fh, '<', $file or die $!; $p->fh( $fh );
Gets or sets the filehandle of the file being read.
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:
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
$p->field_filter( sub { $_ = shift; uc(lc($_)) } );
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. The above example capitalizes field values. To unset the filter, pass in the empty string.
$p->bind_fields( qw[ foo bar baz ] ); my @fields = $p->field_list; print join ', ', @fields; # prints "foo, bar, baz"
Returns the fields bound via bind_fields (or bind_header).
my %positions = $p->field_positions;
Returns a hash of the fields and their positions bound via
bind_fields (or bind_header). Mostly for internal use.
$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
Gets and sets the token to use as the field delimiter. The default is a comma. Regular expressions can be specified using qr//.
$p->filename('/path/to/file.dat');
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.
my @aliases = $p->get_field_aliases('name');
Allows you to define alternate names for fields, e.g., sometimes your input file calls city ``town'' or ``township,'' sometimes a file uses ``Moniker'' instead of ``name.''
$p->header_filter( sub { $_ = shift; s/\s+/_/g; lc $_ } );
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. The above example collapses spaces into a single underscore and lowercases the letters. To unset a filter, pass in the empty string.
$p->record_separator("\n//\n");
$p->field_separator("\n");
Gets and sets the token to use as the record separator. The default is a newline (``\n'').
The above example would read a file that looks like this:
field1 field2 field3 // data1 data2 data3 //
$p->set_field_alias({
name => 'Moniker,handle', # comma-separated string
city => [ qw( town township ) ], # or anonymous arrayref
});
Allows you to define alternate names for fields, e.g., sometimes your input file calls city ``town'' or ``township,'' sometimes a file uses ``Moniker'' instead of ``name.''
my $trim_value = $p->trim(1);
Provide ``true'' argument to remove leading and trailing whitespace from fields. Use a ``false'' argument to disable.
Ken Youens-Clark <kclark@cpan.org>
Thanks to the following:
extract that sets up infinite loops
None known. Please use http://rt.cpan.org/ for reporting bugs.
Copyright (C) 2006 Ken Youens-Clark. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
| Text::RecordParser - read record-oriented files |