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metacpan-examples

This repository contains sample code to get you up and running quickly with the MetaCPAN API.

Please use MetaCPAN::Client

There are many different ways and clients which you can use to access the API. However, we strongly encourage you to start by using the MetaCPAN::Client module. If you have compelling reasons to use a different client, feel free to do so, but please be aware that MetaCPAN::Client is fully supported by MetaCPAN. You will likely save yourself (and us) much debugging time if you begin with this module rather than rolling your own Elasticsearch queries. If MetaCPAN::Client doesn't do something which you need it to do, please open a GitHub issue to let us know about it.

There are some examples to be found here which use curl, WWW::Mechanize, Search::Elasticsearch etc. These are useful for reference, but please do take MetaCPAN::Client as your starting point.

Getting Started

Scripts are all found in /scripts. You can run the Perl scripts in the usual manner, but if you want to get up and running quickly, you are encouraged to run your scripts via Carton. The workflow is:

cpanm Carton
carton install
bin/carton scripts/author/1a-search-authors.pl

Or, you can use Carton directly:

carton exec perl -Ilib scripts/author/1a-search-authors.pl

Using the bin/carton will save you a few keystrokes and will automatically add new libs to the path in future, if they are required. Use the workflow you are most comfortable with.

Please open issues for examples you would like to see and send pull requests for examples you've already written.

Upgrading from v0

The MetaCPAN API v1 is now available. v0 will be deprecated after a 6 month window. This window closes on or after June 1, 2017. Here's a guide to converting your scripts.

Elasticsearch version

v1 of the MetaCPAN API uses Elasticsearch v2.4.0 (v0 was at 0.20.2). There are many breaking changes in this upgrade, since it spans almost 4 years.

The MetaCPAN API versions will increase with breaking changes, but we will not use the same versioning as Elasticsearch itself.

Data Structure Changes

Elasticsearch 1.x changed the data structure returned when fields are used. For example before one could get a ArrayRef[ HashRef [ Str ] ] where now that will come in the form of ArrayRef[ HashRef [ ArrayRef [ Str ] ] ].

Our convenience endpoints revert this behaviour, but if you're crafting your own searches, you should be aware that the structure of your fields data may have changed.

Client-specific Changes

MetaCPAN::Client

v0:

use MetaCPAN::Client->new();

v1:

use MetaCPAN::Client->new( version => 'v1' );

Search::Elasticsearch

v0:

use Search::Elasticsearch;
my $es = Search::Elasticsearch->new(
    cxn_pool => 'Static::NoPing',
    nodes    => 'api.metacpan.org',
    trace_to => 'Stdout',
);

v1:

use Search::Elasticsearch;
my $es = Search::Elasticsearch->new(
    cxn_pool         => 'Static::NoPing',
    nodes            => 'https://fastapi.metacpan.org/v1',
    send_get_body_as => 'POST',
    trace_to         => 'Stdout',
);

  • The node URL of the v1 API is https://fastapi.metacpan.org/v1 Note that not only is the host name new, but we've also switched to https and also added the version to the path.

  • You'll need to set send_get_body_as => 'POST'. This is because v1 does not accept GET with a body.

$es->search
my $faves = $es->search(
    index => 'v0',
    type  => 'favorite',
    body  => {
        query  => { match_all => {} },
        facets => {
            dist => {
                terms => { field => 'favorite.distribution', size => 10 },
            },
        },
    },
    size => 0,
);
my $faves = es()->search(
    index => 'cpan',
    type  => 'favorite',
    body  => {
        aggs => {
            dist => {
                terms => { field => 'distribution', size => 10 },
            },
        },
    },
);
  • The index name is now cpan
  • match_all is the default query type, so it's not required to specify it
  • facets have been replaced by aggs
  • The data structure returned for facets does not mirror the aggs return values, so you'll need to rework your logic when checking the return values.
  • When searching on a type (favorite in this case), do not prefix the key with the type name. So, as seen above, field => 'favorite.distribution' is now field => 'distribution'

GET via command line or browser

v0: http://api.metacpan.org/v0/author/MSTROUT

v1: https://fastapi.metacpan.org/v1/author/MSTROUT

  • Note the new host name
  • Note that we now use HTTPS
  • Note that the path begins with v1 rather than v0