Retrieving large entities or collections increases the response’s size and uses
more bandwidth. You can alleviate this by telling the server via the request
which fields it should include in the response. This is known as
sparse fieldsets. To make a request with sparse fieldsets, include the
fields parameter in the URL with the name of each field’s attribute.
For example, this request doesn’t use sparse fieldsets and therefore returns all the fields of a blog posting:
curl "http://localhost:8080/o/headless-delivery/v1.0/blog-postings/59301" -u 'test@example.com:test'
{
"alternativeHeadline": "The power of OpenAPI & Liferay",
"articleBody": "<p>We are happy to announce...</p>",
"creator": {
"familyName": "Test",
"givenName": "Test",
"id": 20130,
"name": "Test Test",
"profileURL": "/web/test"
},
"dateCreated": "2019-04-22T07:04:47Z",
"dateModified": "2019-04-22T07:04:51Z",
"datePublished": "2019-04-22T07:02:00Z",
"encodingFormat": "text/html",
"friendlyUrlPath": "new-headless-apis",
"headline": "New Headless APIs",
"id": 59301,
"numberOfComments": 0,
"siteId": 20124
}
To get only the headline, creation date, and creator, append the fields
parameter to the URL with the fields headline, dateCreated, and creator:
curl "http://localhost:8080/o/headless-delivery/v1.0/blog-postings/59301?fields=headline,dateCreated,creator" -u 'test@example.com:test'
{
"creator": {
"familyName": "Test",
"givenName": "Test",
"id": 20130,
"name": "Test Test",
"profileURL": "/web/test"
},
"dateCreated": "2019-04-22T07:04:47Z",
"headline": "New Headless APIs"
}
In the response, the creator attribute is a nested JSON object. To return only
the creator’s name, specify that nested field via dot notation (creator.name):
curl "http://localhost:8080/o/headless-delivery/v1.0/blog-postings/59301?fields=headline,dateCreated,creator.name" -u 'test@example.com:test'
{
"creator": {
"name": "Test Test"
},
"dateCreated": "2019-04-22T07:04:47Z",
"headline": "New Headless APIs"
}
The fields parameter also works with collection resources to return the
specified attributes for every collection item. For example, this request gets
the headlines for all the blog postings in the Site with the ID 20124:
curl "http://localhost:8080/o/headless-delivery/v1.0/sites/20124/blog-postings/?fields=headline" -u 'test@example.com:test'
{
"items": [
{
"headline": "New Headless APIs"
},
{
"headline": "Authenticated requests"
}
],
"lastPage": 1,
"page": 1,
"pageSize": 20,
"totalCount": 2
}