处理QueryDSL中的可选参数

Question

我在SpringData中使用QueryDSL。我说表，Employee我创建了实体类，EmployeeEntity 我写了以下 服务 方法

public EmployeeEntity getEmployees(String firstName, String lastName)
{
    QEmployeeEntity employee = QEmployeeEntity.employeeEntity;
    BooleanExpression query = null;
    if(firstName != null)
    {
        query = employee.firstName.eq(firstName);
    }
    if(lastName != null)
    {
        query = query.and(employee.lastName.eq(lastName)); // NPException if firstName is null as query will be NULL
    }
    return empployeeDAO.findAll(query);
}

如上所述，我评论了NPException。如何使用 QueryDSL 在可选参数 QueryDSL 使用Spring的数据？

谢谢 ：）

Answer 1

BooleanBuilder 可以用作布尔表达式的动态生成器：

public EmployeeEntity getEmployees(String firstName, String lastName) {
    QEmployeeEntity employee = QEmployeeEntity.employeeEntity;
    BooleanBuilder where = new BooleanBuilder();
    if (firstName != null) {
        where.and(employee.firstName.eq(firstName));
    }
    if (lastName != null) {
        where.and(employee.lastName.eq(lastName));
    }
    return empployeeDAO.findAll(where);
}