Evan Zacks > CGI-Application-Plugin-Output-XSV > CGI::Application::Plugin::Output::XSV

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NAME ^

CGI::Application::Plugin::Output::XSV - generate csv output from a CGI::Application runmode

SYNOPSIS ^

  use CGI::Application::Plugin::Output::XSV;
  ...

  # in some runmode...

  # $sth is a prepared DBI statement handle
  my $members = $sth->fetchall_arrayref( {} );

  my @headers = qw( member_id first_name last_name ... );

  return $self->xsv_report_web({
    fields     => \@headers,
    values     => $members,
    csv_opts   => { sep_char => "\t" },
    filename   => 'members.csv',
  });


  # or, generate the list on the fly:

  sub get_members { $sth->fetchrow_arrayref() }

  return $self->xsv_report_web({
    iterator   => \&get_members,
    csv_opts   => { sep_char => "\t" },
    filename   => 'members.csv',
  });

DESCRIPTION ^

CGI::Application::Plugin::Output::XSV provides csv-related routines useful for web applications (via Text::CSV_XS).

A method, xsv_report_web is exported by default. Three other functions, xsv_report, clean_field_names, and add_to_xsv are available for optional export.

You may export all four routines by specifying the export tag :all:

  use CGI::Application::Plugin::Output::XSV qw(:all);

PURPOSE ^

On many websites, I had code to retrieve a list of data items for use in an HTML::Template TMPL_LOOP. Usually this code would use the DBI routine fetchall_arrayref() to get a list of hash references, one for each data item.

  my $users = $sth->fetchall_arrayref( {} );

  my $template = $self->load_tmpl( ... );

  $template->param( users => $users );

  return $template->output;

At some point, it would become apparent that an "export to spreadsheet" feature would be useful, so I'd add another runmode, which almost always looked the same:

    my @fields = qw(keys to each data item);

    my $csv = Text::CSV_XS->new();

    foreach my $user ( @{$users} ) {
      $csv->combine( [ @{$user}{@fields} ] );
      $output .= $csv->string() . "\n";
    }

    $self->header_props(
      -type                  => 'application/x-csv',
      '-content-disposition' => "attachment; filename=export.csv",
    );

    return $output;

The purpose of this module is to provide a simple method, xsv_report_web, that wraps the above code while offering a fair amount of programmer flexibility.

For example, the programmer may control the naming of header columns, filter each row of data before it is passed to Text::CSV_XS, and set the filename that is supplied to the user's browser.

Please see the documentation below for xsv_report_web for a list of available options.

METHODS ^

xsv_report_web
  ## METHOD 1. Pre-generated list of values for csv

  # in a runmode

  my @members = (
    { member_id  => 1,
      first_name => 'Chuck',
      last_name  => 'Berry', },
    ...
  );

  my @headers = ("Member ID", "First Name", "Last Name");

  my @fields  = qw(member_id first_name last_name);

  return $self->xsv_report_web({
    fields     => \@fields,
    headers    => \@headers,
    values     => \@members,
    csv_opts   => { sep_char => "\t" },
    filename   => 'members.csv',
  });


  ## METHOD 2. Generate list on the fly

  # in a runmode

  sub get_members { $sth->fetchrow_arrayref() }

  my @headers = ("Member ID", "First Name", "Last Name");

  return $self->xsv_report_web({
    headers    => \@headers,
    iterator   => \&get_members,
    csv_opts   => { sep_char => "\t" },
    filename   => 'members.csv',
    stream     => 1,
  });

This method generates a csv file that is sent directly to the user's web browser. It sets the content-type header to 'application/x-csv' and sets the content-disposition header to 'attachment'.

It should be invoked through a CGI::Application subclass object.

It takes a reference to a hash of named parameters. All except for values or iterator are optional:

csv_opts
  csv_opts   => { sep_char => "\t" },

A reference to a hash of options passed to the constructor of Text::CSV_XS. The default is an empty hash.

fields
  fields => [ qw(member_id first_name last_name) ],

  # or array indices
  fields => [ 1, 2, 0 ],

A reference to a list of field names or array indices. This parameter specifies the order of fields in each row of output.

If fields is not supplied, a list will be generated using the first entry in the values list. Note, however, that in this case, if the values parameter is a list of hashes, the field order will be random because the field names are extracted from a hash. If the values parameter is a list of lists, the field order will be the same as the data provided.

If fields is not supplied and iterator is used instead of values, the field list will be empty.

filename
  filename => 'members.csv',

The name of the file which will be sent in the HTTP content-disposition header. The default is "download.csv".

headers
  headers => [ "Member ID", "First Name", "Last Name" ],

A reference to a list of column headers to be used as the first row of the csv report.

If headers is not supplied (and include_headers is not set to a false value), headers_cb will be called with fields as a parameter to generate column headers.

headers_cb
  # replace underscores with spaces
  headers_cb => sub {
    my $fields = shift;

    # using temp var to avoid modifying $fields
    my @fields_copy = @{$fields};

    return [
      map { tr/_/ /; $_ } @fields_copy
    ];
  },

A reference to a subroutine used to generate column headers from the field names.

A default routine is provided in clean_field_names. This function is passed a reference to the list of fields (fields) as a parameter and should return a reference to a list of column headers.

include_headers
  include_headers => 1,

A true or false value indicating whether to include headers (or automatically generated headers) as the first row of output.

The default is true.

line_ending
  line_ending     => "\n",

The value appended to each line of csv output. The default is "\n".

values
  values => [
    { member_id  => 1,
      first_name => 'Chuck',
      last_name  => 'Berry', },
  ],

  # or a list of lists
  values => [
    [ 1, 'Chuck', 'Berry', ],
  ],

A reference to a list of hash references (such as that returned by the DBI fetchall_arrayref( {} ) routine), or a reference to a list of list references.

Either this argument or iterator must be provided.

iterator
  iterator => sub { $sth->fetchrow_arrayref() },

A reference to a subroutine that is used to generate each row of data. It is passed a reference to the list of fields (fields) as a parameter and should return a reference to a list (which will be passed to add_to_xsv()).

It will be called repeatedly to generate each row of data until it returns a false value.

This may be preferred to values when the data set is large or expensive to generate up-front. Thanks to Mark Stosberg for suggesting this option.

Either this argument or values must be provided.

maximum_iters
  maximum_iters => 1_000_000,

This is the maximum number of times the iterator will be called before an exception is raised. This is a basic stopgap to prevent a runaway iterator that never returns false.

The default is one million.

row_filter
  # uppercase all values
  # (each row is a list of hash references)
  row_filter => sub {
    my ($row, $fields) = @_;

    return [ map { uc } @{$row}{@$fields} ];
  },

A reference to a subroutine used to filter each row of data (other than the header row) before it is passed to add_to_xsv. When the values parameter is supplied, a default filter is provided that produces each row in the order specified by headers. For example, the default filter for a values list of hash references is shown below.

  row_filter => sub {
    my ($row, $fields) = @_;

    return [ @{$row}{@$fields} ];
  },

This subroutine is passed two parameters for each row:

  • the current row (reference to a list of hashes or lists)
  • the field list (fields - reference to a list of hash keys or array indices)

Note: This parameter used to be named get_row_cb. That name is deprecated and a warning will be issued if it is used instead of row_filter.

stream
  stream => 1,

This flag controls whether or not output is printed immediately or collected and returned to the caller. Set to a true value to remove buffering on STDOUT and to emit output as it is generated. This can save memory in the case of a large document, for example.

The default is false to retain backwards-compatibility. In general, it is probably more efficient to set this to a true value, but note that it breaks with the standard CGI::Application convention of returning generated content from your runmodes rather than printing it yourself.

FUNCTIONS ^

add_to_xsv
   # $sth is a prepared DBI statement handle
   my $values  = $sth->fetchall_arrayref( {} );
   my @headers = qw/foo bar baz/;
   my $output;

   # $csv is a Text::CSV_XS object
   foreach my $href ( @{$values} ) {
      $output .= add_to_xsv( $csv, [ @{$href}{@headers} ], "\r\n" );
   }

This function, used internally by xsv_report/xsv_report_web, formats a list of values for inclusion a csv file. The return value is from $csv->string(), where $csv is a Text::CSV_XS object.

It takes three parameters:

  • A Text::CSV_XS object
  • A reference to a list of values
  • The line ending

On an error from Text::CSV_XS, the function raises an exception.

On receiving an empty list of values, the function returns the line ending only.

clean_field_names
  my $fields  = [ qw/first_name foo bar baz/ ];
  my $headers = clean_field_names( $fields );

  # $headers is now [ 'First Name', 'Foo', 'Bar', 'Baz' ]

This function takes a reference to a list of strings and returns a reference to a new list in which the strings are reformatted as such:

  1. Underscores ('_') are changed to spaces
  2. The first letter of each word is capitalized

This function is used by xsv_report and xsv_report_web if the headers_cb parameter is not supplied.

xsv_report
  # $sth is a prepared DBI statement handle
  my $members = $sth->fetchall_arrayref( {} );

  my @headers = qw( member_id first_name last_name ... );

  my $output = $self->xsv_report({
    fields     => \@headers,
    values     => $members,
    csv_opts   => { sep_char => "\t" },
  });

  # do something with $output

This function generates a string containing csv data and returns it.

This may be useful when you want to do some manipulation of the data before sending it to the user's browser or elsewhere. It takes the same named parameters (via a reference to a hash) as xsv_report_web except for filename, which is not applicable to this function.

EXAMPLES ^

Specify (almost) everything
  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
    headers         => [ "First Name", "Last Name", "Phone" ],
    fields          => [ qw(first_name last_name phone) ],
    include_headers => 1,
    line_ending     => "\n",
    csv_opts        => { sep_char => "\t" },
    filename        => 'download.csv',
  });

  __END__
  "First Name"  "Last Name"     Phone
  Jack  Tors    555-1212
  Frank Rizzo   555-1515
Use defaults
  # ends up with same options and output as above

  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
    headers         => [ "First Name", "Last Name", "Phone" ],
    fields          => [ qw(first_name last_name phone) ],
  });
Use header generation provided by module
  # headers generated will be [ "First Name", "Last Name", "Phone" ]

  # same output as above

  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
    fields          => [ qw(first_name last_name phone) ],
  });
Use custom header generation
  # headers generated will be [ "first", "last", "phone" ]

  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
    fields          => [ qw(first_name last_name phone) ],
    headers_cb      => sub {
      my @h = @{ +shift };
      s/_name$// foreach @h;
      return \@h;
    },
  });

  __END__
  first,last,phone
  Jack,Tors,555-1212
  Frank,Rizzo,555-1515
If order of fields doesn't matter
  # headers and fields will be in random order (but consistent
  # throughout data processing) due to extraction from hash

  # (headers will be generated automatically)

  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
  });

  __END__
  Phone,"Last Name","First Name"
  555-1212,Tors,Jack
  555-1515,Rizzo,Frank
No header row
  return $self->xsv_report_web({
    values          => [
      { first_name => 'Jack',
        last_name  => 'Tors',
        phone      => '555-1212' },
      { first_name => 'Frank',
        last_name  => 'Rizzo',
        phone      => '555-1515' },
    ],
    fields          => [ qw(first_name last_name phone) ],
    include_headers => 0,
  });

  __END__
  Jack,Tors,555-1212
  Frank,Rizzo,555-1515
Filter data as it is processed
  sub plus_one {
    my ($row, $fields) = @_;

    return [ map { $_ + 1 } @{$row}{@$fields} ];
  }

  # each row (other than header row) will be
  # passed through plus_one()
  return $self->xsv_report_web({
    fields     => [ qw(foo bar baz) ],
    values     => [ { foo => 1, bar => 2, baz => 3 }, ],
    row_filter => \&plus_one,
  });

  __END__
  Foo,Bar,Baz
  2,3,4
Pass list of lists (instead of hashes)
  # each row will be processed in order
  # since fields parameter is omitted

  $self->xsv_report_web({
    include_headers => 0,
    values          => [
      [ 1, 2, 3 ],
      [ 4, 5, 6 ],
    ],
  });

  __END__
  1,2,3
  4,5,6
Generate each row on the fly
  my @vals = qw(one two three four five six);

  sub get_vals {
    while ( @vals ) {
      return [ splice @vals, 0, 3 ]
    }
  };

  $self->xsv_report_web({
    include_headers => 0,
    iterator        => \&get_vals,
  });

  __END__
  one,two,three
  four,five,six
Generate each row on the fly using a DBI iterator
  my $get_vals = sub { $sth->fetchrow_arrayref() };

  $self->xsv_report_web({
    include_headers => 0,
    iterator        => $get_vals,
  });
Use a DBI iterator, increment each value extracted
  $self->xsv_report_web({
    include_headers => 0,
    iterator        => sub { $sth->fetchrow_arrayref() };
    row_filter      => sub {
      my $row = shift;
      return [ map { $_ + 1 } @{$row} ];
    },
  });

ERROR HANDLING ^

The function add_to_xsv will raise an exception when Text::CSV_XS->combine fails. Please see the Text::CSV_XS documentation for details about what type of input causes a failure.

AUTHOR ^

Evan A. Zacks <zackse@cpan.org>

BUGS ^

Please report any bugs or feature requests to bug-cgi-application-plugin-output-xsv@rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=CGI-Application-Plugin-Output-XSV. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SEE ALSO ^

Text::CSV_XS, CGI::Application

COPYRIGHT AND LICENSE ^

Copyright (c) 2006,2010 CommonMind, LLC. All rights reserved.

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

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