NAME
Catmandu::Importer::getJSON - load JSON-encoded data from a server using
a GET HTTP request
SYNOPSIS
The following three examples are equivalent:
Catmandu::Importer::getJSON->new(
file => \"http://example.org/alice.json\nhttp://example.org/bob.json"
)->each(sub { my ($record) = @_; ... );
Catmandu::Importer::getJSON->new(
url => "http://example.org",
file => \"/alice.json\n/bob.json"
)->each(sub { my ($record) = @_; ... );
Catmandu::Importer::getJSON->new(
url => "http://example.org/{name}.json",
file => \"{\"name\":\"alice\"}\n{\"name\":\"bob\"}"
)->each(sub { my ($record) = @_; ... );
For more convenience the catmandu command line client can be used:
echo http://example.org/alice.json | catmandu convert getJSON to YAML
catmandu convert getJSON --from http://example.org/alice.json to YAML
catmandu convert getJSON --dry 1 --url http://{domain}/robots.txt < domains
DESCRIPTION
This Catmandu::Importer performs a HTTP GET request to load JSON-encoded
data from a server. The importer expects a line-separated input. Each
line corresponds to a HTTP request that is mapped to a JSON-record on
success. The following input formats are accepted:
plain URL
A line that starts with ""http://"" or ""https://"" is used as plain
URL.
URL path
A line that starts with ""/"" is appended to the configured url
parameter.
variables
A JSON object with variables to be used with an URL template or as
HTTP query parameters. For instance the input line "{"name":"Karl
Marx"}" with URL "http://api.lobid.org/person" or the input line
"{"entity":"person","name":"Karl Marx"}" with URL template
"http://api.lobid.org/{entity}{?id}{?name}{?q}" are both expanded to
<http://api.lobid.org/person?name=Karl+Marx>.
If the JSON data returned in a HTTP response is a JSON array, its
elements are imported as multiple items. If a JSON object is returned,
it is imported as one item.
CONFIGURATION
url An URI or an URI templates (URI::Template) as defined by RFC 6570
<http://tools.ietf.org/html/rfc6570> to load JSON from. If no url is
configured, plain URLs must be provided as input or option "from"
must be used instead.
from
A plain URL to load JSON without reading any input lines.
timeout / agent / proxy / headers
Optional HTTP client settings.
client
Instance of a Furl HTTP client to perform requests with.
dry Don't do any HTTP requests but return URLs that data would be
queried from.
file / fh
Input to read lines from (see Catmandu::Importer). Defaults to
STDIN.
fix An optional fix to be applied on every item (see Catmandu::Fix).
wait
Number of seconds to wait between requests.
cache
Cache JSON response of URLs to not request the same URL twice. HTTP
error codes in the 4xx range (e.g. 404) are also cached but 5xx
errors are not.
The value of this option can be any objects that implements method
"get" and "set" (e.g. "CHI"), an existing directory for file
caching, a true value to enable global in-memory-caching, or a false
value to disable caching (default).
File caching uses file names based on MD5 of an URL so for instance
"http://example.org/" is cached as
"4389382917e51695b759543fdfd5f690.json".
METHODS
time
Returns the UNIX timestamp right before the last request. This can be
used for instance to add timestamps or the measure how fast requests
were responded.
construct_url( [ $base_url, ] $vars_url_or_path )
Returns an URL given a hash reference with variables, a plain URL or an
URL path. The optional first argument can be used to override option
"url".
$importer->construct_url( %query_vars )
$importer->construct_url( $importer->url, %query_vars ) # equivalent
request($url)
Perform a HTTP GET request of a given URL including logging, caching,
request hook etc. Returns a hash/array reference or "undef".
EXTENDING
This importer provides two methods to filter requests and responses,
respectively. See Catmandu::Importer::Wikidata for an example.
request_hook
Gets a whitespace-trimmed input line and is expected to return an
unblessed hash reference, an URL, or undef. Errors are catched and
treated equal to undef.
response_hook
Gets the queried response object and is expected to return an object.
LOGGING
URLs are emitted before each request on DEBUG log level.
LIMITATIONS
Future versions of this module may also support asynchronous HTTP
fetching modules such as HTTP::Async, for retrieving multiple URLs at
the same time.
SEE ALSO
Catmandu::Fix::get_json provides this importer as fix function.
COPYRIGHT AND LICENSE
Copyright Jakob Voß, 2014-
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.