Cookbook
Generating custom links in middleware and request handlers
In most cases, you can rely on the ResourceGenerator
to generate self
relational links, and, in the case of paginated collections, pagination links.
What if you want to generate other links to include in your resources, though?
The ResourceGenerator
provides access to the metadata map, hydrators, and link
generator via getter methods:
getMetadataMap()
getHydrators()
getLinkGenerator()
We can thus use these in order to generate custom links as needed.
Creating a custom link to include in a resource
In our first scenario, we'll create a "search" link for a resource.
We'll assume that you have composed a ResourceGenerator
instance in your
middleware, and assigned it to the $resourceGenerator
property.
The link we want to generate will look something like
/api/books?query={searchParms}
, and map to a route named books
.
$searchLink = $this->resourceGenerator
->getLinkGenerator()
->templatedFromRoute(
'search',
$request,
'books',
[],
['query' => '{searchTerms}']
);
You could then compose it in your resource:
$resource = $resource->withLink($searchLink);
Adding metadata for generated links
In our second scenario, we'll consider a collection endpoint. It might include a
per_page
query string argument, to allow defining how many results to return
per page, a sort
argument, and a query
argument indicating the search
string. We know these at runtime, but not at the time we create our
configuration, so we need to inject them after we have our metadata created,
but before we generate our resource, so that the pagination links are
correctly generated.
$queryParams = $request->getQueryParams();
$query = $queryParams['query'] ?? '';
$perPage = $queryParams['per_page'] ?? 25;
$sort = $queryParams['sort'] ?? '';
$metadataMap = $this->resourceGenerator->getMetadataMap();
$metadata = $metadataMap->get(BookCollection::class);
$metadataQuery = $origMetadataQuery = $metadata->getQueryStringArguments();
if ('' !== $query) {
$metadataQuery = array_merge($metadataQuery, ['query' => $query]);
}
if ('' !== $perPage) {
$metadataQuery = array_merge($metadataQuery, ['per_page' => $perPage]);
}
if ('' !== $sort) {
$metadataQuery = array_merge($metadataQuery, ['sort' => $sort]);
}
$metadata->setQueryStringArguments($metadataQuery);
// ...
$resource = $this->resourceGenerator->fromObject($books, $request);
// Reset query string arguments
$metadata->setQueryStringArguments($origMetadataQuery);
This will lead to links with URIs such as
/api/books?query=Adams&per_page=5&sort=DESC&page=4
.
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