REST API: paging

Many REST methods, e.g. the method to fetch databases and the method to fetch profiles, return lists of objects. In order to reduce the amount of time a REST API call takes and to prevent a single call from overtaxing our API servers, the output of these methods is restricted. You are able to set a limit up to 1000 objects. This means you might need to execute a call several times to retrieve all objects if you have many.

Returned data

Whenever a method returns a list of objects, this list is always wrapped in a JSON object. This object has a number of properties that can be used to determine whether the list is complete or whether the output was limited and more entries are available.

    {
        "start":    50,
        "limit":    100,
        "count":    100,
        "total":    335,
        "data":     [ .... ]
    }

The most important property is data, which contains an array with the requested objects; e.g. an array of databases or an array of profiles. The other properties contain numerical values that indicate how many objects were returned and how many are available.

Paging parameters

The property start is the numerical identifier from which to start the list, and the limit property states the maximum number of objects to be returned. The count property contains the number of objects actually returned. In the above example, 100 objects were returned whose identifiers range from 50 to 149. If you don't add a limit to your call the default value of 100 will be used.

The property total contains the total number of available objects. In the above example the total is 335, which means it takes at least 4 calls to retrieve all of the objects. Please note that printing the total is completely optional and choosing not to do so might speed up your calls a lot.

PHP example

The following example demonstrates how to retrieve only the second set of five items from a list of databases.

    // required code
    require_once('copernica_rest_api.php');

    // change this into your access token
    $api = new CopernicaRestAPI("your-access-token", 2);

    // parameters to be passed to the api
    $parameters = array(
        'start'             =>  5,
        'limit'             =>  5,
        'total'             =>  false
    );

    // fetch and print the databases
    print_r($api->get("databases", $parameters));

You need the CopernicaRestApi class to run the example.

More information