auto: Generated builder can't be used for Jackson deserialization

Jackson 2.x supports deserializing JSON by using the builder pattern, so it would be really cool if the following worked:

@AutoValue
@JsonDeserialize(builder = AutoValue_Project.Builder.class)
public abstract class Project {
    public abstract int getId();
    public abstract String getPath();

    public abstract Builder toBuilder();

    @AutoValue.Builder
    interface Builder {
        Project build();

        Builder withId(int id);
        Builder withPath(String path);
    }
}

Unfortunately, the class AutoValue_Project.Builder doesn’t exist at the point the compiler sees the @JsonDeserialize annotation, so this fails to compile. Is there a workaround for this problem?

NB: the best workaround I have at the moment is a creator method

    @JsonCreator
    static Project create(@JsonProperty("id") int id, @JsonProperty("path") String path) {
        return builder()
                .withId(id)
                .withPath(path)
                .build();
    }

About this issue

Original URL
State: closed
Created 9 years ago
Comments: 23 (2 by maintainers)

Most upvoted comments

@vanniktech You need to use your own builder class and put a @JsonCreator method inside the builder:

@AutoValue
@JsonDeserialize(builder = A.Builder.class)
abstract class A {
  static Builder builder() {
    return new AutoValue_A.Builder().a(true).b("default");
  }

  @JsonProperty abstract boolean a();
  @JsonProperty abstract String b();

  @AutoValue.Builder
  @JsonPOJOBuilder(withPrefix = "")
  abstract static class Builder {
    @JsonCreator private static Builder create() { return A.builder(); }
    abstract Builder a(boolean a);
    abstract Builder b(String b);
    abstract A build();
  }

  public static void main(String[] args) throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    System.out.println(mapper.writeValueAsString(A.builder().build()));
    A a = mapper.readValue("{\"a\": false, \"b\": \"non-default\"}", A.class);
    System.out.println(mapper.writeValueAsString(a));
    a = mapper.readValue("{}", A.class);
    System.out.println(mapper.writeValueAsString(a));
  }
}

+11

tbroyer on Jul 12, 2016

Has anyone been able to make it work with default values? Right now in our builder() method we’ll set some default values.

public static Builder builder() {
    return new AutoValue_Class.Builder().a(2).b(3);
}

Unfortunately Jackson won’t take the builder from the builder() method and instead create a new one where the default values for a and b would be missing.

My class is annotated with @JsonDeserialize(builder = AutoValue_Class.Builder.class). I’ve also tried putting @JsonCreator onto the builder() method but that won’t work either.

vanniktech on Jul 12, 2016

any on can help how to do

singha27 on May 24, 2017

Yep, I’m here if you want some help — feel free to connect me!

Actually, Jackson is powerful enough to handle classes with Builders without changes in AutoValue/Jackson.

You can check the example: https://github.com/artem-zinnatullin/AutoJackson

artem-zinnatullin on Sep 24, 2015