Text::CSV_XS - comma-separated values manipulation routines
use Text::CSV_XS;
$csv = Text::CSV_XS->new (); # create a new object
$csv = Text::CSV_XS->new (\%attr); # create a new object
$status = $csv->combine (@columns); # combine columns into a string
$line = $csv->string (); # get the combined string
$status = $csv->parse ($line); # parse a CSV string into fields
@columns = $csv->fields (); # get the parsed fields
$status = $csv->status (); # get the most recent status
$bad_argument = $csv->error_input (); # get the most recent bad argument
$diag = $csv->error_diag (); # if an error occured, explains WHY
$status = $csv->print ($io, $colref); # Write an array of fields
# immediately to a file $io
$colref = $csv->getline ($io); # Read a line from file $io,
# parse it and return an array
# ref of fields
$csv->bind_columns (@refs); # Set return fields for getline ()
$csv->column_names (@names); # Set column names for getline_hr ()
$ref = $csv->getline_hr ($io); # getline (), but returns a hashref
$eof = $csv->eof (); # Indicate if last parse or
# getline () hit End Of File
$csv->types (\@t_array); # Set column types
Text::CSV_XS provides facilities for the composition and decomposition of comma-separated values. An instance of the Text::CSV_XS class can combine fields into a CSV string and parse a CSV string into fields.
The module accepts either strings or files as input and can utilize any user-specified characters as delimiters, separators, and escapes so it is perhaps better called ASV (anything separated values) rather than just CSV.
Important Note: The default behavior is to only accept ascii characters.
This means that fields can not contain newlines. If your data contains
newlines embedded in fields, or characters above 0x7e (tilde), or binary data,
you *must* set binary => 1 in the call to new (). To cover the widest
range of parsing options, you will always want to set binary.
But you still have the problem that you have to pass a correct line to the
parse () method, which is more complicated from the usual point of
usage:
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
while (<>) { # WRONG!
$csv->parse ($_);
my @fields = $csv->fields ();
will break, as the while might read broken lines, as that doesn't care about the quoting. If you need to support embedded newlines, the way to go is either
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
while (my $row = $csv->getline (*ARGV)) {
my @fields = @$row;
or, more safely in perl 5.6 and up
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
open my $io, "<", $file or die "$file: $!";
while (my $row = $csv->getline ($io)) {
my @fields = @$row;
On parsing (both for getline () and parse ()), if the source is
marked being UTF8, then parsing that source will mark all fields that
are marked binary will also be marked UTF8.
On combining (print () and combine ()), if any of the combining
fields was marked UTF8, the resulting string will be marked UTF8.
While no formal specification for CSV exists, RFC 4180 1) describes a common format and establishes "text/csv" as the MIME type registered with the IANA.
Many informal documents exist that describe the CSV format. How To: The Comma Separated Value (CSV) File Format 2) provides an overview of the CSV format in the most widely used applications and explains how it can best be used and supported.
1) http://tools.ietf.org/html/rfc4180 2) http://www.creativyst.com/Doc/Articles/CSV/CSV01.htm
The basic rules are as follows:
CSV is a delimited data format that has fields/columns separated by the comma character and records/rows separated by newlines. Fields that contain a special character (comma, newline, or double quote), must be enclosed in double quotes. However, if a line contains a single entry which is the empty string, it may be enclosed in double quotes. If a field's value contains a double quote character it is escaped by placing another double quote character next to it. The CSV file format does not require a specific character encoding, byte order, or line terminator format.
Though this is the most clear and restrictive definition, Text::CSV_XS is way more liberal than this, and allows extension:
"0 for representation of a
NULL byte.
(Class method) Returns the current module version.
(Class method) Returns a new instance of Text::CSV_XS. The objects
attributes are described by the (optional) hash ref \%attr.
Currently the following attributes are available:
An end-of-line string to add to rows, usually undef (nothing,
default), "\012" (Line Feed) or "\015\012" (Carriage Return,
Line Feed). Cannot be longer than 7 (ASCII) characters.
If both $/ and eol equal "\015", parsing lines that end on
only a Carriage Return without Line Feed, will be parsed correct.
Line endings, whether in $/ or eol, other than undef,
"\n", "\r\n", or "\r" are not (yet) supported for parsing.
The char used for separating fields, by default a comma. (,).
Limited to a single-byte character, usually in the range from 0x20
(space) to 0x7e (tilde).
The separation character can not be equal to the quote character. The separation character can not be equal to the escape character.
When this option is set to true, whitespace (TAB's and SPACE's) surrounding the separation character is removed when parsing. So lines like:
1 , "foo" , bar , 3 , zapp
are now correctly parsed, even though it violates the CSV specs. Note that all whitespace is stripped from start and end of each field. That would make is more a feature than a way to be able to parse bad CSV lines, as
1, 2.0, 3, ape , monkey
will now be parsed as
("1", "2.0", "3", "ape", "monkey")
even if the original line was perfectly sane CSV.
Under normal circumstances, CSV data makes no distinction between quoted- and unquoted empty fields. They both end up in an empty string field once read, so
1,"",," ",2
is read as
("1", "", "", " ", "2")
When writing CSV files with always_quote set, the unquoted empty
field is the result of an undefined value. To make it possible to also
make this distinction when reading CSV data, the blank_is_undef option
will cause unquoted empty fields to be set to undef, causing the above to
be parsed as
("1", "", undef, " ", "2")
The char used for quoting fields containing blanks, by default the
double quote character ("). A value of undef suppresses
quote chars. (For simple cases only).
Limited to a single-byte character, usually in the range from 0x20
(space) to 0x7e (tilde).
The quote character can not be equal to the separation character.
By default, parsing fields that have quote_char characters inside
an unquoted field, like
1,foo "bar" baz,42
would result in a parse error. Though it is still bad practice to allow this format, we cannot help there are some vendors that make their applications spit out lines styled like this.
In case there is really bad CSV data, like
1,"foo "bar" baz",42
or
1,""foo bar baz"",42
there is a way to get that parsed, and leave the quotes inside the quoted
field as-is. This can be achieved by setting allow_loose_quotes AND
making sure that the escape_char is not equal to quote_char.
The character used for escaping certain characters inside quoted fields. Limited to a single-byte character, usually in the range from 0x20 (space) to 0x7e (tilde).
The escape_char defaults to being the literal double-quote mark (")
in other words, the same as the default quote_char. This means that
doubling the quote mark in a field escapes it:
"foo","bar","Escape ""quote mark"" with two ""quote marks""","baz"
If you change the default quote_char without changing the default escape_char, the escape_char will still be the quote mark. If instead you want to escape the quote_char by doubling it, you will need to change the escape_char to be the same as what you changed the quote_char to.
The escape character can not be equal to the separation character.
By default, parsing fields that have escape_char characters that
escape characters that do not need to be escaped, like:
my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
$csv->parse (qq{1,"my bar\'s",baz,42});
would result in a parse error. Though it is still bad practice to allow this format, this option enables you to treat all escape character sequences equal.
If this attribute is TRUE, you may use binary characters in quoted fields,
including line feeds, carriage returns and NULL bytes. (The latter must
be escaped as "0.) By default this feature is off.
If a string is marked UTF8, binary will be turned on automatically when
binary characters other than CR or NL are encountered. Note that a simple
string like "\x{00a0}" might still be binary, but not marked UTF8, so
setting { binary = 1 }> is still a wise option.
meta_info (), is_quoted (), and is_binary ()
described below. Default is false.
This is a quite controversial attribute to set, but it makes hard things possible.
The basic thought behind this is to tell the parser that the normally special characters newline (NL) and Carriage Return (CR) will not be special when this flag is set, and be dealt with as being ordinary binary characters. This will ease working with data with embedded newlines.
When verbatim is used with getline (), getline ()
auto-chomp's every line.
Imagine a file format like
M^^Hans^Janssen^Klas 2\n2A^Ja^11-06-2007#\r\n
where, the line ending is a very specific "#\r\n", and the sep_char is a ^ (caret). None of the fields is quoted, but embedded binary data is likely to be present. With the specific line ending, that shouldn't be too hard to detect.
By default, Text::CSV_XS' parse function however is instructed to only know about "\n" and "\r" to be legal line endings, and so has to deal with the embedded newline as a real end-of-line, so it can scan the next line if binary is true, and the newline is inside a quoted field. With this attribute however, we can tell parse () to parse the line as if \n is just nothing more than a binary character.
For parse () this means that the parser has no idea about line ending anymore, and getline () chomps line endings on reading.
To sum it up,
$csv = Text::CSV_XS->new ();
is equivalent to
$csv = Text::CSV_XS->new ({
quote_char => '"',
escape_char => '"',
sep_char => ',',
eol => '',
always_quote => 0,
binary => 0,
keep_meta_info => 0,
allow_loose_quotes => 0,
allow_loose_escapes => 0,
allow_whitespace => 0,
blank_is_undef => 0,
verbatim => 0,
});
For all of the above mentioned flags, there is an accessor method available where you can inquire for the current value, or change the value
my $quote = $csv->quote_char; $csv->binary (1);
It is unwise to change these settings halfway through writing CSV data to a stream. If however, you want to create a new stream using the available CSV object, there is no harm in changing them.
If the new () constructor call fails, it returns undef, and makes
the fail reason available through the error_diag () method.
$csv = Text::CSV_XS->new ({ ecs_char => 1 }) or
die Text::CSV_XS->error_diag ();
error_diag () will return a string like
"Unknown attribute 'ecs_char'"
$status = $csv->combine (@columns);
This object function constructs a CSV string from the arguments, returning
success or failure. Failure can result from lack of arguments or an argument
containing an invalid character. Upon success, string () can be called to
retrieve the resultant CSV string. Upon failure, the value returned by
string () is undefined and error_input () can be called to retrieve an
invalid argument.
$status = $csv->print ($io, $colref);
Similar to combine, but it expects an array ref as input (not an array!) and the resulting string is not really created, but immediately written to the $io object, typically an IO handle or any other object that offers a print method. Note, this implies that the following is wrong:
open FILE, ">", "whatever"; $status = $csv->print (\*FILE, $colref);
The glob \*FILE is not an object, thus it doesn't have a print
method. The solution is to use an IO::File object or to hide the
glob behind an IO::Wrap object. See IO::File(3) and IO::Wrap(3)
for details.
For performance reasons the print method doesn't create a result string. In particular the $csv->string (), $csv->status (), $csv-fields ()> and $csv->error_input () methods are meaningless after executing this method.
$line = $csv->string ();
This object function returns the input to parse () or the resultant CSV
string of combine (), whichever was called more recently.
$status = $csv->parse ($line);
This object function decomposes a CSV string into fields, returning
success or failure. Failure can result from a lack of argument or the
given CSV string is improperly formatted. Upon success, fields () can
be called to retrieve the decomposed fields . Upon failure, the value
returned by fields () is undefined and error_input () can be called
to retrieve the invalid argument.
You may use the types () method for setting column types. See the description below.
$colref = $csv->getline ($io);
This is the counterpart to print, like parse is the counterpart to combine: It reads a row from the IO object $io using $io->getline () and parses this row into an array ref. This array ref is returned by the function or undef for failure.
When fields are bound with bind_columns (), the return value is a
reference to an empty list.
The $csv->string (), $csv->fields () and $csv->status () methods are meaningless, again.
The getline_hr () and column_names () methods work together to allow
you to have rows returned as hashrefs. You must call column_names ()
first to declare your column names.
$csv->column_names (qw( code name price description ));
$hr = $csv->getline_hr ($io);
print "Price for $hr->{name} is $hr->{price} EUR\n";
getline_hr () will croak if called before column_names ().
Set the keys that will be used in the getline_hr () calls. If no keys
(column names) are passed, it'll return the current setting.
column_names () accepts a list of scalars (the column names) or a
single array_ref, so you can pass getline ()
$csv->column_names ($csv->getline ($io));
column_names () does no checking on duplicates at all, which might
lead to unwanted results. Undefined entries will be replaced with the
string "\cAUNDEF\cA", so
$csv->column_names (undef, "", "name", "name"); $hr = $csv->getline_hr ($io);
Will set $hr-{"\cAUNDEF\cA"}> to the 1st field, $hr-{""}> to the
2nd field, and $hr-{name}> to the 4th field, discarding the 2rd field.
column_names () croaks on invalid arguments.
Takes a list of references to scalars to store the fields fetched
getline () in. When you don't pass enough references to store the
fetched fields in, getline () will fail. If you pass more than there are
fields to return, the remaining references are left untouched.
$csv->bind_columns (\$code, \$name, \$price, \$description);
while ($csv->getline ()) {
print "The price of a $name is \x{20ac} $price\n";
}
$eof = $csv->eof ();
If parse () or getline () was used with an IO stream, this
method will return true (1) if the last call hit end of file, otherwise
it will return false (''). This is useful to see the difference between
a failure and end of file.
$csv->types (\@tref);
This method is used to force that columns are of a given type. For example, if you have an integer column, two double columns and a string column, then you might do a
$csv->types ([Text::CSV_XS::IV (),
Text::CSV_XS::NV (),
Text::CSV_XS::NV (),
Text::CSV_XS::PV ()]);
Column types are used only for decoding columns, in other words by the parse () and getline () methods.
You can unset column types by doing a
$csv->types (undef);
or fetch the current type settings with
$types = $csv->types ();
@columns = $csv->fields ();
This object function returns the input to combine () or the resultant
decomposed fields of parse (), whichever was called more recently.
@flags = $csv->meta_info ();
This object function returns the flags of the input to combine () or
the flags of the resultant decomposed fields of parse (), whichever
was called more recently.
For each field, a meta_info field will hold flags that tell something about
the field returned by the fields () method or passed to the combine ()
method. The flags are bitwise-or'd like:
See the is_*** () methods below.
my $quoted = $csv->is_quoted ($column_idx);
Where $column_idx is the (zero-based) index of the column in the
last result of parse ().
This returns a true value if the data in the indicated column was
enclosed in quote_char quotes. This might be important for data
where ,20070108, is to be treated as a numeric value, and where
,"20070108", is explicitly marked as character string data.
my $binary = $csv->is_binary ($column_idx);
Where $column_idx is the (zero-based) index of the column in the
last result of parse ().
This returns a true value if the data in the indicated column contained any byte in the range [\x00-\x08,\x10-\x1F,\x7F-\xFF]
$status = $csv->status ();
This object function returns success (or failure) of combine () or
parse (), whichever was called more recently.
$bad_argument = $csv->error_input ();
This object function returns the erroneous argument (if it exists) of
combine () or parse (), whichever was called more recently.
Text::CSV_XS->error_diag (); $csv->error_diag (); $error_code = 0 + $csv->error_diag (); $error_str = "" . $csv->error_diag (); ($cde, $str, $pos) = $csv->error_diag ();
If (and only if) an error occured, this function returns the diagnostics of that error.
If called in void context, it will print the internal error code and the associated error message to STDERR.
If called in list context, it will return the error code and the error
message in that order. If the last error was from parsing, the third
value returned is a best guess at the location within the line that was
being parsed. It's value is 1-based. See examples/csv-check for how
this can be used.
If called in scalar context, it will return the diagnostics in a single scalar, a-la $!. It will contain the error code in numeric context, and the diagnostics message in string context.
When called as a class method or a direct function call, the error diag
is that of the last new () call.
$csv->SetDiag (0);
Use to reset the diagnostics if you are dealing with errors.
The arguments to these two internal functions are deliberately not described or documented to enable the module author(s) to change it when they feel the need for it and using them is highly discouraged as the API may change in future releases.
An example for creating CSV files:
my $csv = Text::CSV_XS->new;
open my $csv_fh, ">", "hello.csv" or die "hello.csv: $!";
my @sample_input_fields = (
'You said, "Hello!"', 5.67,
'"Surely"', '', '3.14159');
if ($csv->combine (@sample_input_fields)) {
my $string = $csv->string;
print $csv_fh "$string\n";
}
else {
my $err = $csv->error_input;
print "combine () failed on argument: ", $err, "\n";
}
close $csv_fh or die "hello.csv: $!";
An example for parsing CSV strings:
my $csv = Text::CSV_XS->new ({ keep_meta_info => 1, binary => 1 });
my $sample_input_string =
qq{"I said, ""Hi!""",Yes,"",2.34,,"1.09","\x{20ac}",};
if ($csv->parse ($sample_input_string)) {
my @field = $csv->fields;
foreach my $col (0 .. $#field) {
my $quo = $csv->is_quoted ($col) ? $csv->{quote_char} : "";
printf "%2d: %s%s%s\n", $col, $quo, $field[$col], $quo;
}
}
else {
my $err = $csv->error_input;
print STDERR "parse () failed on argument: ", $err, "\n";
$csv->error_diag ();
}
Dumping the content of a database ($dbh) table ($tbl) to CSV:
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
open my $fh, ">", "$tbl.csv" or die "$tbl.csv: $!";
my $sth = $dbh->prepare ("select * from $tbl");
$sth->execute;
$csv->print ($fh, $sth->{NAME_lc});
while (my $row = $sth->fetch) {
$csv->print ($fh, $row) or ...;
}
close $fh or die "$tbl.csv: $!";
Reading a CSV file line by line:
my $csv = Text::CSV_XS->new ({ binary => 1 });
open my $fh, "<", "file.csv" or die "file.csv: $!";
while (my $row = $csv->getline ($fh)) {
# do something with @$row
}
close $fh or die "file.csv: $!";;
For more extended examples, see the examples/ subdirectory in the
original distribution. Included is examples/parser-xs.pl, that could
be used to `fix' bad CSV
perl examples/parser-xs.pl bad.csv >good.csv
For all possible errors, there should be a test.
All XS code should be covered in the test cases, except for perl internal failure, like failing to store a hash value.
New extensions ought to be clear and concise in reporting what error occurred where and why, and possibly also tell a remedy to the problem. error_diag is a (very) good start, but there is more work to be done here.
Basic calls should croak or warn on illegal parameters. Errors should be documented.
Discuss an option to make the eol honor the $/ setting. Maybe
my $csv = Text::CSV_XS->new ({ eol => $/ });
is already enough, and new options only make things less opaque.
Future extensions might include extending the meta_info (),
is_quoted (), and is_binary () to accept setting these flags
for fields, so you can specify which fields are quoted in the
combine ()/string () combination.
$csv->meta_info (0, 1, 1, 3, 0, 0); $csv->is_quoted (3, 1);
combine () and
string () in a single call will not be honored. Likewise for
parse () and fields (). Given the trouble with embedded newlines,
Using getline () and print () instead is the prefered way to go.
We probably need many more tests to check if all edge-cases are covered. See t/50_utf8.t.
Probably the best way to do this more reliable is to make a subclass Text::CSV_XS::Encoded that can be passed the required encoding and then behaves transparently (but slower), something like this:
use Text::CSV::Encoded;
my $csv = Text::CSV::Encoded->new ({
encoding => "utf-8", # Both in and out
encoding_in => "iso-8859-1", # Only the input
encoding_out => "cp1252", # Only the output
});
Implement a new methods that enables the parsing of a complete file at once, returning a lis of hashes. Possible extension to this could be to enable a column selection on the call:
my @AoH = $csv->parse_file ($filename, { cols => [ 1, 4..8, 12 ]});
Returning something like
[ { fields => [ 1, 2, "foo", 4.5, undef, "", 8 ],
flags => [ ... ],
errors => [ ... ],
},
{ fields => [ ... ],
.
.
},
]
No guarantees, but this is what I have in mind right now:
- This might very well be 1.00 - DIAGNOSTICS setction in pod to *describe* the errors (see below) - croak / carp
- allow_double_quoted - Text::CSV_XS::Encoded (maybe)
- csv2csv - a script to regenerate a CSV file to follow standards - EBCDIC support
Still under construction ...
If an error occured, $csv-error_diag ()> can be used to get more information
on the cause of the failure. Note that for speed reasons, the internal value
is never cleared on success, so using the value returned by error_diag () in
normal cases - when no error occured - may cause unexpected results.
Currently errors as described below are available. I've tried to make the error itself explanatory enough, but more descriptions will be added. For most of these errors, the first three capitals describe the error category:
eol has been set to something specific, other than the default,
like "\r\t\n", and the "\r" is following the second (closing)
quote_char, where the characters following the "\r" do not make up
the eol sequence, this is an error.
1,foo,"bar"baz,2 are not allowed. "bar" is a quoted
field, and after the closing quote, there should be either a new-line
sequence or a separation character.
getline (), as using parse ()
is done on strings that are not required to have a trailing eol.
1,"foo\nbar",2 are only allowed when the binary option
has been selected with the constructor.
1,"foo\rbar",2 are only allowed when the binary option
has been selected with the constructor.
"foo "bar" baz",quux and 2023,",2008-04-05,"Foo, Bar",\n
will cause this error.
perl(1), IO::File(3), L{IO::Handle(3)>, IO::Wrap(3), Text::CSV(3), Text::CSV_PP(3). and Spreadsheet::Read(3).
Alan Citterman <alan@mfgrtl.com> wrote the original Perl module. Please don't send mail concerning Text::CSV_XS to Alan, as he's not involved in the C part which is now the main part of the module.
Jochen Wiedmann <joe@ispsoft.de> rewrote the encoding and decoding in C by implementing a simple finite-state machine and added the variable quote, escape and separator characters, the binary mode and the print and getline methods. See ChangeLog releases 0.10 through 0.23.
H.Merijn Brand <h.m.brand@xs4all.nl> cleaned up the code, added the field flags methods, wrote the major part of the test suite, completed the documentation, fixed some RT bugs. See ChangeLog releases 0.25 and on.
Copyright (C) 2007-2008 H.Merijn Brand for PROCURA B.V. Copyright (C) 1998-2001 Jochen Wiedmann. All rights reserved. Portions Copyright (C) 1997 Alan Citterman. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.