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Posted to dev@sling.apache.org by "Henry Kuijpers (Jira)" <ji...@apache.org> on 2023/05/16 12:29:00 UTC
[jira] [Updated] (SLING-11881) @ChildResource Collection in combination with @PostConstruct Boolean method can cause injection to stop working and inject an empty collection

     [ https://issues.apache.org/jira/browse/SLING-11881?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Henry Kuijpers updated SLING-11881:
-----------------------------------
    Description: 
Let's say we have a Sling Model with a parameter:
{code:java}
@ChildResource(name = "links", injectionStrategy = OPTIONAL) final Collection<Link> links)
{code}

And Link is implemented as follows:
{code:java}
@Model(adaptables = Resource.class, adapters = LinkModel.class)
public class Link {
    private final String url;

    @Inject
    public LinkModel(@ValueMapValue(name = "url", injectionStrategy = InjectionStrategy.OPTIONAL) final String url) {
        this.url = url;
    }

    @PostConstruct
    public boolean activate() {
        // Returning false here indicates that the model is not valid (null will be returned, instead of the instantiated model)
        return StringUtils.isNotEmpty(url);
    }
}
{code}

In case the content structure looks like this:
{code}
links/item0/jcr:primaryType=nt:unstructured
links/item0/url=test0
links/item1/jcr:primaryType=nt:unstructured
links/item2/jcr:primaryType=nt:unstructured
links/item2/url=test2
{code}
I would expect the following to be the value of the @ChildResource parameter, when adapting:
links=[url=test0, url=test2]

However, an empty collection is injected instead.

I believe this is because of the following lines:
https://github.com/apache/sling-org-apache-sling-models-impl/blob/a348e50f9321af27dea513d0367b813d3afce9e2/src/main/java/org/apache/sling/models/impl/ModelAdapterFactory.java#L1044

The logic here seems to be that if one of the various items cannot be adapted, an empty collection is returned, instead of a collection ommitting the item that could not be adapted.

  was:
Let's say we have a Sling Model with a parameter:
{code:java}
@ChildResource(name = "links", injectionStrategy = OPTIONAL) final Collection<Link> links)
{code}

And Link is implemented as follows:
{code:java}
@Model(adaptables = Resource.class, adapters = LinkModel.class)
public class Link {
    private final String url;

    @Inject
    public LinkModel(@ValueMapValue(name = "url", injectionStrategy = InjectionStrategy.OPTIONAL) final String url) {
        this.url = url;
    }

    @PostConstruct
    public boolean activate() {
        // Returning false here indicates that the model is not valid (null will be returned, instead of the instantiated model)
        return StringUtils.isNotEmpty(url);
    }
}
{code}

In case the content structure looks like this:
{code}
items/item0/jcr:primaryType=nt:unstructured
items/item0/url=test0
items/item1/jcr:primaryType=nt:unstructured
items/item2/jcr:primaryType=nt:unstructured
items/item2/url=test2
{code}
I would expect the following to be the value of the @ChildResource parameter, when adapting:
links=[url=test0, url=test2]

However, an empty collection is injected instead.

I believe this is because of the following lines:
https://github.com/apache/sling-org-apache-sling-models-impl/blob/a348e50f9321af27dea513d0367b813d3afce9e2/src/main/java/org/apache/sling/models/impl/ModelAdapterFactory.java#L1044

The logic here seems to be that if one of the various items cannot be adapted, an empty collection is returned, instead of a collection ommitting the item that could not be adapted.


> @ChildResource Collection<MyModel> in combination with @PostConstruct Boolean method can cause injection to stop working and inject an empty collection
> -------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: SLING-11881
>                 URL: https://issues.apache.org/jira/browse/SLING-11881
>             Project: Sling
>          Issue Type: Bug
>          Components: Sling Models
>    Affects Versions: Sling Models Impl 1.4.0
>            Reporter: Henry Kuijpers
>            Priority: Major
>
> Let's say we have a Sling Model with a parameter:
> {code:java}
> @ChildResource(name = "links", injectionStrategy = OPTIONAL) final Collection<Link> links)
> {code}
> And Link is implemented as follows:
> {code:java}
> @Model(adaptables = Resource.class, adapters = LinkModel.class)
> public class Link {
>     private final String url;
>     @Inject
>     public LinkModel(@ValueMapValue(name = "url", injectionStrategy = InjectionStrategy.OPTIONAL) final String url) {
>         this.url = url;
>     }
>     @PostConstruct
>     public boolean activate() {
>         // Returning false here indicates that the model is not valid (null will be returned, instead of the instantiated model)
>         return StringUtils.isNotEmpty(url);
>     }
> }
> {code}
> In case the content structure looks like this:
> {code}
> links/item0/jcr:primaryType=nt:unstructured
> links/item0/url=test0
> links/item1/jcr:primaryType=nt:unstructured
> links/item2/jcr:primaryType=nt:unstructured
> links/item2/url=test2
> {code}
> I would expect the following to be the value of the @ChildResource parameter, when adapting:
> links=[url=test0, url=test2]
> However, an empty collection is injected instead.
> I believe this is because of the following lines:
> https://github.com/apache/sling-org-apache-sling-models-impl/blob/a348e50f9321af27dea513d0367b813d3afce9e2/src/main/java/org/apache/sling/models/impl/ModelAdapterFactory.java#L1044
> The logic here seems to be that if one of the various items cannot be adapted, an empty collection is returned, instead of a collection ommitting the item that could not be adapted.



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