如何在一个 controller API 和 ZCCADCDEDB567ABAE643E15DCF0974E503Z 中发出多个“查找”请求？

Question

I have one API to consult data from database. So I want to make multiple "FIND" query on mongoose, join all the responses and send back the result from the query. I am using Nodejs and Express to make the API and Mongoose.

exports.data = (req, res) => {
    //FIND ALL CONSULTATIONS FILTERED BY STATUS
    const result1 = Model.find({ status: 'STATUS1' }).exec(
        (err, item) => {
            if (err) {
                return res.status(400).json({
                    error: 'Erorr en STATUS1',
                });
            }
            
        }
    );
    const result2 = Model.find({ status: 'STATUS2' }).exec(
        (err, item) => {
            if (err) {
                return res.status(400).json({
                    error: 'Erorr en STATUS2',
                });
            }
        }
    );


    res.json({result1, result2})

};

something like that, but it does not work. How can I achieve that? Make just one API call and response, but in the controller ask for different data, make one object and send it back.

Answer 1

Your current problem is that node will start the first find, and before it's done it'll start the second find, and before either of those are done it'll send back the result which will likely be { result1: undefined, result2: undefined }

You need to wait for the result before you send it back.

Your options are callback-hell, promises or async-await. Pick your poison.

// callback hell
Model.find({ status: 'STATUS1' }).exec((err, result1) => {
  if (err) {
    return res.status(400).json({
      error: 'Erorr en STATUS1'
    })
  }
  Model.find({ status: 'STATUS2' }).exec((err, result2) => {
    if (err) {
      return res.status(400).json({
        error: 'Erorr en STATUS2'
      })
    }
    res.json({ result1, result2 })
  })
})

// Promises
exports.data = async (req, res) => {
  //FIND ALL CONSULTATIONS FILTERED BY STATUS
  const promise1 = Model.find({ status: 'STATUS1' }).exec()
  const promise2 = Model.find({ status: 'STATUS2' }).exec()
  Promise.all([promise1, promise2])
    .then(([result1, result2]) => {
      res.json({ result1, result2 })
    })
    .catch(err => {
      return res.status(400).json({
        error: 'Erorr en STATUS2'
      })
    })
}

// Async Await
exports.data = async (req, res) => {
  //FIND ALL CONSULTATIONS FILTERED BY STATUS
  let result1
  let result2
  try {
    result1 = await Model.find({ status: 'STATUS1' }).exec()
  } catch (err) {
    return res.status(400).json({
      error: 'Erorr en STATUS1'
    })
  }
  try {
    result2 = await Model.find({ status: 'STATUS2' }).exec()
  } catch (err) {
    return res.status(400).json({
      error: 'Erorr en STATUS2'
    })
  }
  res.json({ result1, result2 })
}

None of the code above has been tested. It's just to give you a rough idea.

While promises looks cleaner here, I almost always opt for using async/await when I can. And since this is express, it makes sense to use express style error handler (and factor out the try-catches) which would make async-await look much cleaner.