/ 
Catmandu-1.2024
River stage two • 81 direct dependents • 87 total dependents
/ Catmandu::Importer

NAME

Catmandu::Importer - Namespace for packages that can import

SYNOPSIS


            

              
              
# From the command line
# JSON is an importer and YAML an exporter
$ catmandu convert JSON to YAML < data.json
# OAI is an importer and JSON an exporter
$ catmandu convert OAI --url http://biblio.ugent.be/oai to JSON 
# Fetch remote content
$ catmandu convert JSON --file http://example.com/data.json to YAML
# From Perl
use Catmandu;
use Data::Dumper;
my $importer = Catmandu->importer('JSON', file => 'data.json');
$importer->each(sub {
    my $item = shift;
    print Dumper($item);
});
my $num = $importer->count;
my $first_item = $importer->first;
# Convert OAI to JSON in Perl
my $importer = Catmandu->importer('OAI', url => 'http://biblio.ugent.be/oai');
my $exporter = Catmandu->exporter('JSON');
$exporter->add_many($importer);

DESCRIPTION

A Catmandu::Importer is a Perl package that can generate structured data from sources such as JSON, YAML, XML, RDF or network protocols such as Atom, OAI-PMH, SRU and even DBI databases. Given an Catmandu::Importer a programmer can read data from using one of the many Catmandu::Iterable methods:


            

              
              
$importer->to_array;
$importer->count;
$importer->each(\&callback);
$importer->first;
$importer->rest;
...etc...

Every Catmandu::Importer is also Catmandu::Fixable and thus inherits a 'fix' parameter that can be set in the constructor. When given a 'fix' parameter, then each item returned by the generator will be automatically Fixed using one or more Catmandu::Fixes. E.g.


            

              
              
my $importer = Catmandu->importer('JSON',fix => ['upcase(title)']);
$importer->each( sub {
    my $item = shift ; # Every $item->{title} is now upcased... 
});
# or via a Fix file
my $importer = Catmandu->importer('JSON',fix => ['/my/fixes.txt']);
$importer->each( sub {
    my $item = shift ; # Every $item->{title} is now upcased... 
});

CONFIGURATION

file

Read input from a local file given by its path. If the path looks like a url, the content will be fetched first and then passed to the importer. Alternatively a scalar reference can be passed to read from a string.

fh

Read input from an IO::Handle. If not specified, Catmandu::Util::io is used to create the input stream from the file argument or by using STDIN.

encoding

Binmode of the input stream fh. Set to :utf8 by default.

fix

An ARRAY of one or more Fix-es or Fix scripts to be applied to imported items.

data_path

The data at data_path is imported instead of the original data.


            

              
              
# given this imported item:
{abc => [{a=>1},{b=>2},{c=>3}]}
# with data_path 'abc', this item gets imported instead:
[{a=>1},{b=>2},{c=>3}]
# with data_path 'abc.*', 3 items get imported:
{a=>1}
{b=>2}
{c=>3}
variables

Variables given here will interpolate the file and http_body options. The syntax is the same as URI::Template.


            

              
              
# named arguments
my $importer = Catmandu->importer('JSON',
    file => 'http://{server}/{path}',
    variables => {server => 'biblio.ugent.be', path => 'file.json'},
);
# positional arguments
my $importer = Catmandu->importer('JSON',
    file => 'http://{server}/{path}',
    variables => 'biblio.ugent.be,file.json',
);
# or
my $importer = Catmandu->importer('JSON',
    url => 'http://{server}/{path}',
    variables => ['biblio.ugent.be','file.json'],
);
# or via the command line
$ catmandu convert JSON --file 'http://{server}/{path}' --variables 'biblio.ugent.be,file.json'

HTTP CONFIGURATION

These options are only relevant if file is a url. See LWP::UserAgent for details about these options.

http_body

Set the GET/POST message body.

http_method

Set the type of HTTP request 'GET', 'POST' , ...

http_headers

A reference to a HTTP::Headers objects.

Set an own HTTP client

user_agent(LWP::UserAgent->new(...))

Set an own HTTP client

Alternative set the parameters of the default client

http_agent

A string containing the name of the HTTP client.

http_max_redirect

Maximum number of HTTP redirects allowed.

http_timeout

Maximum execution time.

http_verify_hostname

Verify the SSL certificate.

http_retry

Maximum times to retry the HTTP request if it temporarily fails. Default is not to retry. See LWP::UserAgent::Determined for the HTTP status codes that initiate a retry.

http_timing

Maximum times and timeouts to retry the HTTP request if it temporarily fails. Default is not to retry. See LWP::UserAgent::Determined for the HTTP status codes that initiate a retry and the format of the timing value.

METHODS

first, each, rest , ...

See Catmandu::Iterable for all inherited methods.

CODING

Create your own importer by creating a Perl package in the Catmandu::Importer namespace that implements Catmandu::Importer. Basically, you need to create a method 'generate' which returns a callback that creates one Perl hash for each call:


            

              
              
my $importer = Catmandu::Importer::Hello->new;
$importer->generate(); # record
$importer->generate(); # next record
$importer->generate(); # undef = end of stream

Here is an example of a simple Hello importer:


            

              
              
package Catmandu::Importer::Hello;
use Catmandu::Sane;
use Moo;
with 'Catmandu::Importer';
sub generator {
    my ($self) = @_;
    state $fh = $self->fh;
    my $n = 0;
    return sub {
        $self->log->debug("generating record " . ++$n);
        my $name = $self->fh->readline;
        return defined $name ? { "hello" => $name } : undef;
    };
}
1;

This importer can be called via the command line as:


            

              
              
$ catmandu convert Hello to JSON < /tmp/names.txt
$ catmandu convert Hello to YAML < /tmp/names.txt
$ catmandu import Hello to MongoDB --database_name test < /tmp/names.txt

Or, via Perl


            

              
              
use Catmandu;
my $importer = Catmandu->importer('Hello', file => '/tmp/names.txt');
$importer->each(sub {
    my $items = shift;
});

SEE ALSO

Catmandu::Iterable , Catmandu::Fix , Catmandu::Importer::CSV, Catmandu::Importer::JSON , Catmandu::Importer::YAML