mongoDB 与 nodejs 返回数据

Question

I have my own class and method call findByIdDate() When I find the data then inside of db.collection() I will get result but if I want to return that data from my own method it will come back undefined. Could someone provide me example how to get the data please? I have been searching but I can not find any answers to this problem. I'm new to node and express My Method

findByIdDate(){
    let data = this.db.collection('journal').find({date: this.Date}).toArray((err, result) => {
        if(err){return console.log(err)}
        console.log(result) // I have data
        return result
    })
    return data
}

in my other file I use it like this

app.post('/id', (req, res) => {

  const DIARY = new diary('new', '16 January 2020', db)
  let result = DIARY.findByIdDate()
  console.log(result) // undefined 

});

Answer 1

It would be best to do away with callback functions and make the function async/await as:

async findByIdDate(){
    try {
        let data = await this.db.collection('journal')
            .find({date: this.Date})
            .toArray() // returns a promise which can be 'awaited'
        console.log(data)
        return data
    } catch (err) {
        console.error(err)
        throw err
    }
}

And use it in your route as

app.post('/id', async (req, res) => {
    try {
        const DIARY = new diary('new', '16 January 2020', db)
        let result = await DIARY.findByIdDate()
        console.log(result) 
    } catch(err) {
        console.error(err)
    }    
})