IllegalArgumentException：找不到命名参数 [surname]，期待 [name] 之一

Question

我的 studentRepository 类：

    private static EntityManagerFactory emf = null;

    public EntityManager em() {
        if (emf == null) {
            emf = Persistence.createEntityManagerFactory("teachermanagementPU");
        }
        EntityManager entityManager = emf.createEntityManager();
        return entityManager;
    }

    public List<StudentEntity> getAll(String name, String surname, Integer age, BigDecimal scholarship) {
        String jpql = "select u from StudentEntity u where 1=1";

        if (name != null && !name.trim().isEmpty()) {
            jpql += "and u.name=:name";
        }

        if (surname != null && !surname.trim().isEmpty()) {
            jpql += "and u.surname=:surname";
        }

        if (age != null) {
            jpql += "and u.age=:age";
        }
        if (scholarship != null) {
            jpql += "and u.scholarship=:scholarship";
        }

        EntityManager em = em();//JPQL
        Query query = em.createQuery(jpql, StudentEntity.class);

        if (name != null && name.trim().isEmpty()) {
            query.setParameter("name", name);
        }

        if (surname != null && surname.trim().isEmpty()) {
            query.setParameter("surname", surname);
        }

        if (age != null) {
            query.setParameter("age", age);
        }

        if (scholarship != null) {
            query.setParameter("scholarship", scholarship);
        }
        List<StudentEntity> students = query.getResultList();
        em.close();
        return students;
    }

我收到错误 IllegalArgumentException：找不到命名参数 [surname]，期待 [name] 之一 Students.jsp 类：

StudentRepository studentRepository = new StudentRepository();
List<StudentEntity> students = studentRepository.getAll(
        request.getParameter("name"),
        request.getParameter("surname"),
        request.getParameter("age") != null && !request.getParameter("age").isEmpty() ? Integer.parseInt(request.getParameter("age")) : null,
        request.getParameter("scholarship") != null && !request.getParameter("scholarship").isEmpty() ? new BigDecimal(request.getParameter("scholarship")) : null);

Answer 1

连接字符串时需要加一个空格：

if (name != null && !name.trim().isEmpty()) {
    jpql += " and u.name=:name ";
}

其他地方也一样。

你也忘记了感叹号!：

if (surname != null && !surname.trim().isEmpty()) {
                
    query.setParameter("surname", surname);

}

你可以使用isBlank:

if (surname != null && !surname.isBlank()) {
    ...
}