BeanWrapper does not support objects that are maps/arrays/lists them-selves [SPR-2058]

[spring-projects-issues]

Alex Antonov opened SPR-2058 and commented

When a BeanWrapper wraps an object that is a map or a collection of sorts, it has trouble retrieving a value using a key property
i.e.
Person p = new Person("John");
Map map = new HashMap();
map.put("key", person);
BeanWrapperImpl wrapper = new BeanWrapperImpl(map);
String name = wrapper.getPropertyValue("[key].name")

This kind of access is very possible when comming from a web-layer using a bind-path of something like [key].name when the top-level object is itself a map.
In this case, when calling errros.rejectValue("[key].name", ...) in the validator, the call throws an exception due to inability to find an object referenced by [key].

Currently a work-around this problem is to subclass a map and provide a getter for every key you might have in the map, so that the path looks like key.name, but
this approach requires a lot of overhead of the getter creation.

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11 votes, 9 watchers

[spring-projects-issues]

Juergen Hoeller commented

IMO, this does not qualify as a bug - it's rather a well-known, intentional limitation. We can of course reconsider whether we actually want to support Collection/Map objects directly, despite them not actually being JavaBeans.

Juergen

[spring-projects-issues]

Dave Syer commented

I think it would be useful, especially in web apps, especially when prototyping.

I believe commons-beanutils PropertyUtils works sort of in the way described above, so people may already be used to it.

The only difficult decision I can see is what to do with properties that are not already keys in the map. In commons-beanutils if I do PropertyUtils.getProperty(map,"key") I get null irrespective of whether the key already existed. Maybe I would prefer it to barf with an invalid property exception. This would make the behaviour BeanWrapper more consistent between the map and non-map cases.

[spring-projects-issues]

Juergen Hoeller commented

Closing groups of outdated issues. Please reopen if still relevant.