MongoDB 中带有可选字段的过滤方法

Question

我想在 node.js 和 mongodb 中编写一个方法来过滤用户

1. 批次和课程 2) 如果课程未输入则仅批次 3) 如果批次未输入则仅课程

 //filter students by either course or batch export const getUsersByCourseOrBatch = async (req, res) => { try { const { course, batch } = req.body if(course, batch) { const users = await UserModel.find({ course: course, batch: batch }) } else if(course) { const users = await UserModel.find({ course: course }) } else { const users = await UserModel.find({ batch: batch }) } res.status(200).json({ message: `Users from course ${course} and batch ${batch}`, users, }) } catch (error) { res.status(500).json({ message: error.message }) } }

Answer 1

您可以构建自定义过滤器 object：

export const getUsersByCourseOrBatch = async (req, res) => {
  try {
    const { course, batch } = req.body;
    const filter = {};
    if (course) filter.course = course;
    if (batch) filter.batch = batch;
    const users = await UserModel.find(filter);
    res.status(200).json({
      message: `Users from course ${course} and batch ${batch}`,
      users,
    });
  } catch (error) {
    res.status(500).json({ message: error.message });
  }
};