NAME

WebService::GData::Query - implements the core query parameters available in the google data API v2.

SYNOPSIS

    use WebService::GData::Query;
	use WebService::GData::Constants qw(:format :query :general);

    #create an object that only has read access
    my $query = new WebService::GData::Query();

    $query->to_query_string();# by default:?alt=json&v=2&prettyprint=true&strict=true

    #?alt=jsonc&v=2&prettyprint=true&strict=true&start-index=1&max-results=10
    $query->alt('jsonc')->limit(10,1)->to_query_string();

    print $query->get('alt');#json-c

	$query->v(1);#throw an error as only 2 is ok.
	$query->prettyprint(1);#throw an error as only 'true' or 'false' is possible.

	#use constants where you can 

	$query->prettyprint(TRUE);

	$query->alt('json-c');#this is wrong

	$query->alt(JSONC);#ok!

DESCRIPTION

inherits from WebService::GData.

Google data API supports searching different services via a common set of parameters.

Unfortunately, some services only handles a subset of this "core" parameters...

You should read the service Query documentation to know exactly the available parameters.

This package also implements some helpers functions to shorten up a little the parameter settings.

In order to avoid to send uncorrect parameter values, the package checks for their validity

and will throw a WebService::GData::Error object containing 'invalid_parameter_type' as the code and the name of the function as the content.

Checking the data before hands, will avoid unnecessary network transactions and

reduce the risk of reaching quota limitations in use for the service you are querying.

WebService::GData::Constants contains predefined value that you can use to set the parameters.

Using the constants can avoid typo errors or unnecessary code change when an update is available with a new value.

CONSTRUCTOR

new

Creates a basic query instance.

The following parameters are set by default:

alt= WebService::GData::Constants::JSON

v= WebService::GData::Constants::GDATA_MINIMUM_VERSION

prettyprint= WebService::GData::Constants::FALSE

strict= WebService::GData::Constants::TRUE

Parameters:

none

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->to_query_string();# by default:?alt=json&v=2&prettyprint=false&strict=true

GENERAL METHODS

get

Returns the parameter specified.

The function uses the underscore nomenclature where the parameters use the hyphen nomenclature.

You should change all the underscore to hyphen when accessing the value.

Parameters:

parameter_name:Scalar

Return parameter_value::Scalar

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->get('alt');#json

	$query->get('published_min');#does not work...

	$query->get('published-min');#ok!

to_query_string

Concatene each parameter/value pair into a query string.

This function is also called in a string overload context. "$instance" is the same as $instance->to_query_string();

Parameters:

none

Return:query_string:Scalar

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->to_query_string();#?alt=json&v=2&prettyprint=true&strict=true
	"$query";                 #?alt=json&v=2&prettyprint=true&strict=true
	print $query;             #?alt=json&v=2&prettyprint=true&strict=true

PARAMETER METHODS

All the methods that set a parameter return the instance so that you can chain the function calls.

Example:

$query->alt(JSONC)->limit(10,1)->strict(TRUE)->prettyprint(FALSE)->to_query_string();

The following setters are available:

strict

If set to true (default), setting a parameter not supported by a service will fail the request.

Parameters:

true_or_false:Scalar

The value can be WebService::Gdata::Constants::TRUE or WebService::Gdata::Constants::FALSE

Return:WebService::GData::Query

Throw:WebService::GData::Error

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->strict('true');

	$query->strict(TRUE);#better

	$query->strict('hello');#die

fields

Allows you to query partial data.

This is a Google data experimental feature as of this version.

Parameters:

partial_query:Scalar

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->fields('id,entry(author)');#only get the id and the author in the entry tag

See Also:

The reference for the partial queries:

http://code.google.com/intl/en/apis/gdata/docs/2.0/reference.html#PartialResponse

v

Set the google Data API version number. Default to WebService::GData::Constants::GDATA_MINIMUM_VERSION.

You shoud not set this unless you know what you do.

alt

Specify the response format used. Default to WebService::GData::Constants::JSON.

You shoud not set this unless you know what you do.

prettyprint

If set to true (default false),the result from the service will contain indentation.

Parameters:

true_or_false:Scalar (Default: WebService::Gdata::Constants::TRUE)

The value can be WebService::Gdata::Constants::TRUE or WebService::Gdata::Constants::FALSE

Return:WebService::GData::Query

Throw:WebService::GData::Error

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->prettyprint('true');

	$query->prettyprint(TRUE);#better

	$query->prettyprint('hello');#die

author

Specify the author of the contents you want to retrieve.

Each service derives the meaning for their own feed.

Parameters:

author_name:Scalar

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->author('GoogleDeveloper');

updated_min

Retrieve the contents which update date is a minimum equal to the one specified (inclusive).

Note that you should retrieve the value as 'updated-min' when used with WebService::GData::Query::get().

Parameters:

date:Scalar

Format:2005-08-09T10:57:00-08:00

Return:WebService::GData::Query

updated_max

Retrieve the contents which update date is at maximum equal to the one specified (exclusive).

Note that you should retrieve the value as 'updated-max' when used with WebService::GData::Query::get().

Parameters:

date:Scalar

Format:2005-08-09T10:57:00-08:00

Return:WebService::GData::Query

published_min

Retrieve the contents which publish date is a minimum equal to the one specified (inclusive).

Note that you should retrieve the value as 'published-min' when used with WebService::GData::Query::get().

Parameters:

date:Scalar

Format:2005-08-09T10:57:00-08:00

Return:WebService::GData::Query

published_max

Retrieve the contents which publish date is a maximum equal to the one specified (exclusive).

Note that you should retrieve the value as 'published-max' when used with WebService::GData::Query::get().

Parameters:

date:Scalar

Format:2005-08-09T10:57:00-08:00

Return:WebService::GData::Query

start_index

Retrieve the contents starting from a certain result. Start from 1.

Setting 0 will revert to 1.

Note that you should retrieve the value as 'start-index' when used with WebService::GData::Query::get().

Parameters:

index_number:Int

Setting the number to 0 or anything but an integer will coerce it to 1.

Return:WebService::GData::Query

max_results

Retrieve the contents up to a certain amount of entry (Most of the services set it to 25 by default).

Note that you should retrieve the value as 'max-results' when used with WebService::GData::Query::get().

Parameters:

index_number:Int

Setting the number to 0 or anything but an integer will coerce it to 1.

Return:WebService::GData::Query

limit

An extension that allows you to set start_index and max_results in one method call:

get('limit') will return undef.

Follow the same coercicion logic of start_index and max_results.

Parameters:

max_results:Int

The number of result you want to get back

start_index:Int

The offset from where to start

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->limit(10,5);
	#equivalent to
	$query->max_results(10)->start_index(5);	

q

insensitive freewords search where:

words in quotation means exact match:"word1 word2"

words separated by a space means AND:word1 word2

words prefixed with an hyphen means NOT(containing):-word1

Parameters:

search:Scalar

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->q('"exact phrase" snowbaord sports -ski');

category

Allow to narrow down the result to specifics categories.

words separated by a comma(,) means AND:word1,word2

words separated by a pipe(|) means OR:word1|word2

words prefixed by an hyphen(-) are disgarded:-word1

Parameters:

category:Scalar

Return:WebService::GData::Query

Example:

	use WebService::GData::Query;

    #create an object that only has read access
	my $query = new WebService::GData::Query();

	$query->category('-Shows,Entertainment|Sports');

SEE ALSO

Documentation of the parameters:

http://code.google.com/intl/en/apis/gdata/docs/2.0/reference.html#Queries

CONFIGURATION AND ENVIRONMENT

none

DEPENDENCIES

none

INCOMPATIBILITIES

none

BUGS AND LIMITATIONS

If you do me the favor to _use_ this module and find a bug, please email me i will try to do my best to fix it (patches welcome)!

AUTHOR

shiriru <shirirulestheworld[arobas]gmail.com>

LICENSE AND COPYRIGHT

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

cpanm WebService::GData

perl -MCPAN -e shell
install WebService::GData