android - 在 Android 上使用 ORMLite 保存集合时出现问题

Question

我有两个类(class):

public class Questionnaire {

    @DatabaseField(generatedId=true, useGetSet=true)
    private Long id;

    @DatabaseField
    private int type;

    @DatabaseField
    private String title;

    @DatabaseField
    private String description;


    @ForeignCollectionField(eager = true)   
    private Collection<Question> questions; 
// Get and Set omitted

和

  public class Question {

        @DatabaseField(generatedId=true, useGetSet=true)
        private Long id;

        @DatabaseField
        private int type;

        @DatabaseField
        private String description;


        @DatabaseField(foreign = true, foreignAutoRefresh= true)
        private Questionnaire questionario;
//get and set ommited

当我保存带有问题列表的问卷时。对象被保留，但我失去了关系。

我是这样保存的:

ForeignCollection<Question> questions =
    getDao(Questionnaire.class).getEmptyForeignCollection("questions");

for(Question question : DataUtil.getAllQuestions()) {
    questions.add(question);
}

Questionnaire questionnarie = new Questionnaire();
questionnarie.setQuestions(questions);
questionnarie.setTitle("Normal");
questionnarie.setDescription("Questionário normal");
getDao(Questionnaire.class).createOrUpdate(questionarie);

当我从数据库中检索此寄存器时，Questionnaire 数据没有Questionnaire 的引用，而我的Questionnaire 也没有填写问题列表。

我们将不胜感激。

Answer 1

问题是您没有在Question 对象上设置questionario 字段。该关系是从Question 到关联的Questionnaire。 Questionnaire 表中没有任何内容指向另一个方向。查看documentation on foreign objects .

我建议您执行以下操作:

Dao<Questionnaire, Long> dao = getDao(Questionnaire.class);
ForeignCollection<Question> questions =
    dao.getEmptyForeignCollection("questions");

Questionnaire questionnarie = new Questionnaire();
questionnarie.setQuestions(questions);
questionnarie.setTitle("Normal");
questionnarie.setDescription("Questionário normal");
dao.createOrUpdate(questionarie);

for(Question question : DataUtil.getAllQuestions()) {
    // you must set the questionnarie field on the Question
    // if it is a generated-id, it must be set _after_ it has been created
    question.setQuestionnaire(questionnarie);
    questions.add(question);
}