Can not deserialize cached json data to AsyncResult

Question

I'm using spring cache with redis implementation, I have following method

@Async
@Cacheable(key = "#id")
public Future<Student> getStudent(String id){
  Student stu  = ...;
  return new AsyncResult<>(stu);
}

When I visit the method first time, the data is cached into redis in json format.

but when I visit it the second time, it occurs some error like this:

java.util.concurrent.ExecutionException: org.springframework.data.redis.serializer.SerializationException: Could not read JSON: Cannot construct instance of org.springframework.scheduling.annotation.AsyncResult (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

[EDIT]

I found a workaround : new a MyAsyncReslt.java which extends AsyncResult and add the NoArgsContructor.

It seems to be serialization problem. Do you properly implemented `Serializable` on `Student`? — Xarvalus, May 11 '19 at 20:10

Xarvalus · Accepted Answer · 2019-05-13T09:32:10.783

Redis Serializer uses Jackson under the hood Class Jackson2JsonRedisSerializer, the error:

Cannot construct instance of org.springframework.scheduling.annotation.AsyncResult (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

Seems to be outcoming from Jackson (can't deserialize without default constructor):

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of Type (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

Ensure you have your model class Student properly structured to be compliant with Jackson Jackson - Object Serialization as it is used in AsyncResult via generics.

Edit in accordance to OP question:

I found a workaround : new a MyAsyncReslt.java which extends AsyncResult and add the NoArgsContructor.

Spring's AsyncResult seems not to be properly implemented to be serialized with Jackson (check on Github spring-projects/spring-framework: AsyncResult).

public class AsyncResult<V> implements ListenableFuture<V> {
    // ...

    public AsyncResult(@Nullable V value) {
        this(value, null);
    }

    private AsyncResult(@Nullable V value, @Nullable Throwable ex) {
        this.value = value;
        this.executionException = ex;
    }

    // Missing empty constructor to comply with Jackson requirements:
    public AsyncResult() {}

// ...

Until the issue will be patched you can extend Spring's AsyncResult and provide the required empty constructor. Freely use your custom AsyncResult in code.

The error say it cannot deserialize the AsyncResult ,which is provided by spring and not under my controller — rellocs wood, May 12 '19 at 11:33
@rellocswood `AsyncResult<>` takes `Student` as generic, that's why I think the `Student` class might have Jackson's deserialization problems. Does the `Student` comply with all the needs of Jackson library? Does changing it makes any difference in outcoming error? — Xarvalus, May 12 '19 at 11:40
when i cache the Student directly it works, when I add AsyncResult it fails — rellocs wood, May 12 '19 at 12:13
@rellocswood I have updated the answer with your recent discoveries and some explanation. You might consider making PR into Spring to patch the lacking functionality — Xarvalus, May 13 '19 at 09:33

Can not deserialize cached json data to AsyncResult

1 Answers1