java - 处理 QueryDSL 中的可选参数

Question

我正在使用 QueryDSL 和 SpringData。我有表说 Employee 并且我创建了实体类说 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，我注释了 NPException。如何使用 QueryDSL 使用 Spring Data 在 QueryDSL 中使用可选参数？

谢谢你:)

Answer 1

BooleanBuilder 可用作 boolean 表达式的动态构建器:

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);
}