Default value initialization dosen work with Lombok

Question

I have this pojo class, which is used as apart of REST request

@Data
@Builder
public class ListRequest {
    
    @ApiModelProperty(
            value = "Language, default=en",
            allowableValues = "fr, de, sv, en",
            example = "en"
    )
    private Language language=Language.en;

  
    @Transient
    @ApiModelProperty(hidden = true)
    private String apiVersion = "v4";
}

I expect that the value of language will be Language.en if it is missing from the service request However it is always null.

It is Java 101 to initialize the variable that way, so I guess it is Lombok which made this issue.

Any idea what is the issue here?

EDIT: I use neither the constructor nor the builder in my code, its the spring boot who instantiate the objects.

If your're only using `ListRequest` in a Spring Controller your a) not using the builder at all and could remove that annotation (there are issues when using the builder with defaults https://stackoverflow.com/q/47883931/995891) b) spring might actively sets the language property to `null`, e.g. when your client sends json request objects that have `"language": null` in them. What spring should do in your case is `new ListRequest()` then set properties — zapl, Sep 20 '22 at 10:33

score 2 · Answer 1 · answered Sep 20 '22 at 09:37

2

Please try below. @Builder will create the attribute with null by default

@Default
private Language language=Language.en;

answered Sep 20 '22 at 09:37

Hai Mai

39
3

score 1 · Answer 2 · answered Sep 20 '22 at 09:19

Property for which no value is specified in the builder call will be null. Even if you try to set a default value other than null and write it in the target class, it will not work.

To set the default value, describe the builder class with the naming convention of target class name + Builder as shown below. The rest is nicely complemented by Lombok.

import lombok.Builder;
import lombok.Data;
import lombok.Value;

    @Data
    @Builder
    public class ListRequest {
    
        @ApiModelProperty(
                value = "Language, default=en",
                allowableValues = "fr, de, sv, en",
                example = "en"
        )
        private Language language=Language.en;
    
    
        public static class ListRequestBuilder {
            private Language language=Language.en;
        }
        @ApiModelProperty(hidden = true)
        private String apiVersion = "v4";
    
    
    }

score 0 · Answer 3 · answered Sep 20 '22 at 12:10

Here is how i managed to fix it, thanks to all the contributors. Apparently there is an issue when try to init default value in lombok with both constructor and builder Default value in lombok. How to init default with both constructor and builder

And unfortunately the annotation @Default didnot fix the issue

I removed the @Builder from the class and added @NoArgsConstructor , and created a new constructor with the annotation @Builder, and excluded all the field i need to init from that constructor

    @Data
    @NoArgsConstructor
    public class ListRequest {
    
        @ApiModelProperty(
                value = "Language, default=en",
                allowableValues = "fr, de, sv, en",
                example = "en"
        )
        private Language language=Language.en;
    
        @ApiModelProperty(hidden = true)
        private String apiVersion;
    
        @Builder
        public ListRequest(String apiVersion){
           this.apiVersion=apiVersion;
        }

    }

Default value initialization dosen work with Lombok

3 Answers3