I'm trying to marshal a list: List<Pojo>
objects via the Spring Rest Template.
I can pass along simple Pojo
objects, but I can't find any documentation that describes how to send a List<Pojo>
objects.
Spring is using Jackson JSON to implement the HttpMessageConverter
. The jackson documentation covers this:
In addition to binding to POJOs and
"simple" types, there is one
additional variant: that of binding to
generic (typed) containers. This case
requires special handling due to
so-called Type Erasure (used by Java
to implement generics in somewhat
backwards compatible way), which
prevents you from using something like
Collection<String>.class
(which does
not compile).
So if you want to bind data into a
Map<String,User>
you will need to use:
Map<String,User> result = mapper.readValue(src, new TypeReference<Map<String,User>>() {});
where TypeReference
is only needed to
pass generic type definition (via
anynomous inner class in this case):
the important part is
<Map<String,User>>
which defines type
to bind to.
Can this be accomplished in the Spring template? I took a glance at the code and it makes me thing not, but maybe I just don't know some trick.
Solution
The ultimate solution, thanks to the helpful answers below, was to not send a List, but rather send a single object which simply extends a List, such as: class PojoList extends ArrayList<Pojo>
. Spring can successfully marshal this Object, and it accomplishes the same thing as sending a List<Pojo>
, though it be a little less clean of a solution. I also posted a JIRA in spring for them to address this shortcoming in their HttpMessageConverter
interface.
See Question&Answers more detail:
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