Links and Pagination

Links

Content returned from the Lightroom APIs often includes a base URL and table of relative links that should be used when assembling subsequent requests. To ensure the most robust future-proofing, clients should avoid cobbling together their own fully formed URLs when possible.

For example, the API to retrieve a catalog might return (unique identifiers have been shortened to preserve readability):

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{
    "base": "https://lr.adobe.io/v2/catalogs/18c23e15/",
    ...
    "links" {
        "self": {
            "href": "/v2/catalogs/18c23e15"
        },
        "/rels/albums": {
            "href": "albums"
        }
    }
}
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{
    "base": "https://lr.adobe.io/v2/catalogs/18c23e15/",
    ...
    "links" {
        "self": {
            "href": "/v2/catalogs/18c23e15"
        },
        "/rels/albums": {
            "href": "albums"
        }
    }
}

To construct the API endpoint to enumerate the albums in the catalog, an application should concatenate the base with the /rels/albums value in href. When composing these two elements into a single URL, clients should use the standard rules for URI resolution as defined in section 5.2 of RFC 3986. We strongly recommend that clients use standard library implementations to avoid worrying about corner cases of the RFC URI rules.

Pagination

Indefinitely long lists of content, such as albums and assets, may be paginated during their return. Therefore, a client may need to make multiple calls to enumerate the entire list. The links subsection of returned content will contain a next field that encapsulates the API call for fetching an additional page of assets. Sample recursive JavaScript might be:

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function getPagedJSONContentP(url) {
    return new Promise(function(resolve, reject) {
        var response = {
            resources: []
        }
        function getPage(url) {
            getJSONContentP(url).then(function(page) {
                response.base = page.base
                response.resources = response.resources.concat(page.resources)
                if (page.links.next) {
                    getPage(page.base + page.links.next.href)
                }
                else {
                    resolve(response)
                }
            }, reject)
        }
        getPage(url)
    })
}
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function getPagedJSONContentP(url) {
    return new Promise(function(resolve, reject) {
        var response = {
            resources: []
        }
        function getPage(url) {
            getJSONContentP(url).then(function(page) {
                response.base = page.base
                response.resources = response.resources.concat(page.resources)
                if (page.links.next) {
                    getPage(page.base + page.links.next.href)
                }
                else {
                    resolve(response)
                }
            }, reject)
        }
        getPage(url)
    })
}

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