Agfdhyk

good day everyone,

i have this spring rest api that i'm building, and currently having a problem with the put method on my of controllers.

i have a question entity that has a relation with a test entity:

@Id

@GeneratedValue(strategy = GenerationType.SEQUENCE)

@Column(name="question_id", nullable = false, updatable = false)

private Long id;



@Column(name="question_text", nullable = false)

@NotNull

private String question;



@Column(name="question_weight", nullable = false)

@Min(1)

private Integer weight = 1;



@Column(name="question_type", nullable = false)

private String type = "radio";



@Temporal(TemporalType.TIMESTAMP)

@Column(name = "last_modified", nullable = false)

@LastModifiedDate

private Date lastModified;



@ManyToOne(fetch = FetchType.LAZY, optional = false, targetEntity = com.QCMGenerator.QCMGenerator.Model.Test.class)

@JoinColumn(name = "test_id", referencedColumnName = "test_id", nullable = false, updatable = false)

@OnDelete(action = OnDeleteAction.CASCADE)

@JsonIgnore

private Test test;

i posted earlier asking about this problem and i've been told to use the DTOs, so i did and here is my question DTO:

private Long id;



private String question;



private String type;



private Integer weight;



private Date lastModified;



private TestDTO test;

and this the put method i have in my controller:

@PutMapping("/{questionID}")

public QuestionDTO updateQuestion(

        @PathVariable(value = "testID") Long testID,

        @PathVariable(value = "questionID") Long questionID,

        @Valid @RequestBody QuestionDTO newQuestion

){

    if(!testRepo.existsById(testID)){

        throw new ResourceNotFoundException("No test with the ID '"+testID+"' was found...");

    }



    QuestionDTO savedDTO = null;



    try {

        Question questionEntity = questionRepo.findById(questionID).get();

        QuestionDTO questionDTO = convertToDTO(questionEntity);

        if (newQuestion.getTest() != null) {

            questionDTO.setTest(newQuestion.getTest());

        }

        if (newQuestion.getQuestion() != null) {

            questionDTO.setQuestion(newQuestion.getQuestion());

        }

        if (newQuestion.getType() != null) {

            questionDTO.setType(newQuestion.getType());

        }

        if (newQuestion.getWeight() != null) {

            questionDTO.setWeight(newQuestion.getWeight());

        }

        Question newQuestionEntity = convertToEntity(questionDTO);

        Question saved = questionRepo.save(newQuestionEntity);

        savedDTO = convertToDTO(saved);

    }catch (Exception e){

        System.out.println(e.getMessage());

    }



    return savedDTO;

}

and i keep getting this error on my IDE console:

2018-11-18 21:33:12.249 WARN 12876 --- [nio-8080-exec-2] o.h.a.i.UnresolvedEntityInsertActions : HHH000437: Attempting to save one or more entities that have a non-nullable association with an unsaved transient entity. The unsaved transient entity must be saved in an operation prior to saving these dependent entities.
Unsaved transient entity: ([com.QCMGenerator.QCMGenerator.Model.Test#])
Dependent entities: ([[com.QCMGenerator.QCMGenerator.Model.Question#10]])
Non-nullable association(s): ([com.QCMGenerator.QCMGenerator.Model.Question.test])
org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : com.QCMGenerator.QCMGenerator.Model.Question.test -> com.QCMGenerator.QCMGenerator.Model.Test; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : com.QCMGenerator.QCMGenerator.Model.Question.test -> com.QCMGenerator.QCMGenerator.Model.Test

i was hoping someone here would clarify this problem for me as i have been stuck all day long just on that single method or the other methods work fine, i have tried with and without a DTO and before adding it i was having a problem with the method accepting null values on certain fields.

i really appreciate any help given and thank you all for your help.

have a good day everyone. :D

This error occurs when you are trying to save an entity association with null id.
Means is this case convertToEntity method in
Question newQuestionEntity = convertToEntity(questionDTO);

returns questionEntity with new Test object.
you should check all relations inside an entity for being null when their id is null.

You need add ID in your entity in order to save an entity with that ID as reference.

Easy to solve it:

Question newQuestionEntity = convertToEntity(questionDTO);

newQuestionEntity.setId(testID);

A best solution would be:

questionDTO.setID(testID);

public Question convertToEntity(QuestionDTO qDto) {

       Question question = new Question(qDto.getID()) ;

        ....... 

        return question;

}