json您能告诉我如何在@Query（“{ask'：？0}”）上正确编辑这个java注释mongodb吗？

Question

此批注搜索文档。文档有一个包含值的数组。注释在数组中搜索匹配项。如果存在匹配项，则返回文档。但如果没有匹配项，则此注释将继续工作，而不返回任何内容。Spring返回java.lang error.NullPointerException: null。用户的请求已排队，下一个请求也已排队。如何从@Query返回null

{
    "_id":{"$oid":"5fa6cdf065249ffc1282e880"},   
    "ask":["java",  
        "what is java",  
        "java is"],  
    "answer":"Java is a class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible"
}

所以我在找

@Repository
public interface PostRepository extends MongoRepository<Answer, String> {

    @Query("{ 'ask': ?0}")
    public Answer findAnswerByAsk(String ask);
}

```java
@Data
@Document(collection = "answer")
public class Answer{

    @Id
    private String id;
    @Field("ask")
    private String[] ask;
    @Field("answer")
    private String answer;
    @Field("keyWords")
    private String[] keyWords;

    public Answer(String[] ask, String answer, String[] keyWords) {
        this.ask = ask;
        this.answer = answer;
        this.keyWords = keyWords;
    }

    public Answer(){}

}

Answer 1

问题不在于此，此记录100%有效，问题在于豆子