使用 mongodb、mongoose 和 nodejs 设置限制和偏移后获取收集总数

Question

I have seen several questions on this topic on Google but I am not sure why any of them is working for me.

I am simply trying to query a data from collection with limit and offset passing which seems working fine but I need one more parameter where it returns the total no. of data available in that collection.

Is it that hard? I have spend over 12 hours just for this. Must be I am a beginner in Nodejs and mongodb.

With my research I found that db.collection(collection_name).count())

should return total count. But it shows blank object where it is placed. I again came to know that it is being depreciated and now we should use Collection.countDocuments or Collection.estimatedDocumentCount . Again check the documents of mongodb . As per the document it says: db.orders.countDocuments({}) where I replaced the orders with my collection name which becomes. db.allMinisters.countDocuments({})

I get this error {"error":{"message":"Cannot read property 'countDocuments' of undefined"}} . I even use db.collection('allMinisters').countDocuments({}) but it return promise and display blank object as count.

My code:-

    mongoose.connect( url, (err, database) => { 
        if(err) {
            return console.error(err);
        }
        db = database;

    });

    exports.getAllMinisters = (req, res, next)=>{
        console.log(db.collection('allMinisters').countDocuments({}));
        db.collection('allMinisters').find({}).skip(0).limit(10).toArray(function (err, docs) {
            if (err) {return next(err);}
              const response = {
                  count: db.collection('allMinisters').count(),
                  allMinisters: docs.map(docs=>docs),
                  status: 'success'
              }
  
            res.statusCode = 200;
            res.setHeader('Content-Type', 'application/json');
            res.end(JSON.stringify(response));
          });
      };

How do I get total count?

Answer 1

I am not sure how your REST API looks like but try something like this

exports.getallMinisters = async (req, res, next) => {
  if (req.params.docs) {
    const allMinisters = await allMinister.find({ docs: req.params.docs });

    return res.status(200).json({
      success: true,
      count: allMinisters.length,
      data: allMinisters
    });
  } else {
    //errorResponse;
  }
};

Answer 2

Thanks to @ashok.

I manage to fixed this by simply creating async based function and await the total count query.

exports.getAllMinisters = async (req, res, next)=>{
        totalCount  = await db.collection('allMinisters').countDocuments({});
        db.collection('allMinisters').find({}).skip(0).limit(10).toArray(function (err, docs) {
            if (err) {return next(err);}
              const response = {
                  count: totalCount,
                  allMinisters: docs.map(docs=>docs),
                  status: 'success'
              }
  
            res.statusCode = 200;
            res.setHeader('Content-Type', 'application/json');
            res.end(JSON.stringify(response));
          });
      };