On Mon, Jan 30, 2023 at 11:53 AM itineric itineric <[email protected]> wrote:
>
> Hi all,
>
> I'm trying to work with interfaces and related bean implementation of that
> interface. So far, all good.
> I then tried to add some Map<String, Object> to the equation and I cannot
> understand why I get this result.
> Short story: I'm trying to get the @class to be set to the interface name
> using a TypeIdResolver and it work as expected on a direct call but not when
> the object is inside a Map.
Although I did not read the example in detail, I think you are bumping
into the same problem as countless other developers: Java Type
Erasure.
Meaning that passing root-level values that have generic type will NOT
have their type information available.
Try this by wrapping your `Map` into wrapper like:
public class MapWrapper {
public Map<String, Object> parameters;
}
and serialize that.
More specifically if you pass `Map` directly into ObjectMapper, it is
only seen as `Map<?.?>`
This is problematic because you need the base type of Map values to be
`UserInterface` I think.
So type must be seen as `Map<String, UserInterface>` or so.
If possible maybe you should try creating helper type, something like:
public class UserTypeMap extends HashMap<String, UseInterface> { }
since it would contain necessary type information (being concrete
type, not generic).
-+ Tatu +-
> I simplified everything to get an example, here it is :
>
> UserInterface.java
> @JsonTypeInfo(use = Id.CLASS)
> @JsonTypeIdResolver(UserTypeResolver.class)
> public interface UserInterface
> {
> String getName();
> }
>
> UserImplementation.java
> public class UserImplementation implements UserInterface
> {
> private String name;
>
> @Override
> public String getName()
> {
> return this.name;
> }
>
> public void setName(final String name)
> {
> this.name = name;
> }
> }
>
> UserTypeResolver.java
> public class UserTypeResolver implements TypeIdResolver
> {
> private JavaType baseType;
>
> @Override
> public void init(final JavaType baseType)
> {
> this.baseType = baseType;
> }
>
> @Override
> public String idFromValue(final Object value)
> {
> return idFromValueAndType(value, value.getClass());
> }
>
> @Override
> public String idFromValueAndType(final Object value, final Class<?>
> suggestedType)
> {
> return "com.example.jackson.UserInterface";
> }
>
> @Override
> public String idFromBaseType()
> {
> return idFromValueAndType(null, this.baseType.getRawClass());
> }
>
> @Override
> public JavaType typeFromId(final DatabindContext context, final String id)
> throws IOException
> {
> return
> TypeFactory.defaultInstance().constructSpecializedType(this.baseType,
> UserImplementation.class);
> }
>
> @Override
> public String getDescForKnownTypeIds()
> {
> return null;
> }
>
> @Override
> public Id getMechanism()
> {
> return Id.CLASS;
> }
> }
>
> And finally the test I played:
>
> final UserImplementation user = new UserImplementation();
> user.setName("test");
>
> final Map<String, Object> parameters = new HashMap<>();
> parameters.put("user", user);
>
> final ObjectMapper mapper = new ObjectMapper();
> mapper.enableDefaultTyping(DefaultTyping.JAVA_LANG_OBJECT, As.PROPERTY);
>
> StringWriter writer = new StringWriter();
> mapper.writeValue(writer, user);
> System.out.println(writer);
>
> writer = new StringWriter();
> mapper.writeValue(writer, parameters);
> System.out.println(writer);
>
> The output is:
> {"@class":"com.example.jackson.UserInterface","name":"test"}
> {"user":{"@class":"com.example.jackson.UserImplementation","name":"test"}}
>
> The expected output I'd like to see:
> {"@class":"com.example.jackson.UserInterface","name":"test"}
> {"user":{"@class":"com.example.jackson.UserInterface ","name":"test"}}
>
> What am I doing wrong? Is that the expected output? What could I do to get
> the one I expect?
>
> Thank you
>
>
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