json-path/JsonPath · error · UnsupportedOperationException

Tapestry JSON provider does not support TypeRef! Use a Jacks

Error message

Tapestry JSON provider does not support TypeRef! Use a Jackson or Gson based provider

What it means

TapestryMappingProvider.map(Object, TypeRef<T>, Configuration) is deliberately unimplemented: it always throws UnsupportedOperationException with this message. TypeRef (generic super-type-token) mapping is not supported by the Tapestry provider, so any generic type request fails unconditionally, regardless of the source value.

Source

Thrown at json-path/src/main/java/com/jayway/jsonpath/spi/mapper/TapestryMappingProvider.java:51

      if (targetType.isAssignableFrom(ArrayList.class) && configuration.jsonProvider().isArray(source)) {
        int length = configuration.jsonProvider().length(source);
        @SuppressWarnings("rawtypes")
        ArrayList list = new ArrayList(length);
        for (Object o : configuration.jsonProvider().toIterable(source)) {
          list.add(o);
        }
        return (T) list;
      }
    } catch (Exception e) {

    }
    throw new MappingException("Cannot convert a " + source.getClass().getName() + " to a " + targetType
        + " use Tapestry's TypeCoercer instead.");
  }

  @Override
  public <T> T map(final Object source, final TypeRef<T> targetType, final Configuration configuration) {
    throw new UnsupportedOperationException(
        "Tapestry JSON provider does not support TypeRef! Use a Jackson or Gson based provider");
  }

}

View on GitHub (pinned to 62a4c9f0f6)

Solutions

Switch the mapping provider: Configuration.setMappingProvider(new JacksonMappingProvider()) or GsonMappingProvider — both support TypeRef.
If Tapestry must stay, map to the raw Class type (List.class/Map.class) and convert elements manually.
Use JsonPath.parse(...).read(path) to get a plain Object/JSONArray and transform it yourself.
Ensure a single provider is used consistently; avoid Tapestry for generic-type mapping.

Example fix

// before
Configuration conf = Configuration.defaultConfiguration(); // Tapestry/default path
List<Foo> list = JsonPath.read(json, "$[*]", new TypeRef<List<Foo>>(){}, conf); // UnsupportedOperationException
// after
Configuration conf = Configuration.defaultConfiguration()
    .setMappingProvider(new JacksonMappingProvider());
List<Foo> list = JsonPath.read(json, "$[*]");

Defensive patterns

Strategy: fallback

Validate before calling

MappingProvider mp = configuration.mappingProvider();
if (mp instanceof TapestryMappingProvider && usesTypeRef)
    throw new IllegalStateException("Configure JacksonMappingProvider/GsonMappingProvider for TypeRef support");

Try / catch

try {
    List<Foo> list = JsonPath.parse(json).read("$[*]", new TypeRef<List<Foo>>(){}, configuration);
} catch (UnsupportedOperationException e) {
    Configuration jacksonCfg = configuration.setMappingProvider(new JacksonMappingProvider());
    List<Foo> list = JsonPath.parse(json).read("$[*]", new TypeRef<List<Foo>>(){}, jacksonCfg);
}

Prevention

Never pair TypeRef-based reads with TapestryMappingProvider; it is unimplemented by design.
Default to JacksonMappingProvider or GsonMappingProvider when you need generic type tokens.
Centralize Configuration setup so the provider choice is explicit and audited in one place.
When stuck on Tapestry, map to raw Class targets (Map/List) and convert elements manually.

When it happens

Trigger: Any call to map(source, new TypeRef<List<MyType>>(){}, configuration) — or JsonPath reads with .map(new TypeRef<T>(){}) — while TapestryMappingProvider is the configured mapping provider.

Common situations: Reading JSON arrays into typed Lists (JsonPath.parse(...).read("$[*]", new TypeRef<List<Foo>>(){})) with the Tapestry provider; copying configuration/code from a Jackson- or Gson-based setup without changing the provider.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of json-path/JsonPath@62a4c9f0f6 (2026-09-11). Data as JSON: /api/errors/b6680aa29fd2589b. Report an issue: GitHub.