节点js异步mongodb find（）查询多个调用

Question

I fetched the records using

find().toArray()

query. In that records, there is relation id of other document(table). I want to get records of relation table of each record of above find query result. Like:

   db.collection('serviceBooking').find({'request_to_sp_user_id': docs._id.toString()}).toArray(function (err, serviceBookingDocs) {
        if (serviceBookingDocs.length) {
            var asyncCalls = [];
            serviceBookingDocs.forEach(function (bookingRecord, key) {
                var temp = {};
                temp.userDetails = {};
                //Async call for getting the user details for all users
                asyncCalls.push(function (callback) {
                    db.collection('userDetails').findOne({'user_id': new mongo.ObjectID(bookingRecord.booked_by_user_id)}, function (err, userDetailsDocs) {
                        db.collection('serviceBookingDetails').find({'serviceBookingId': bookingRecord._id.toString()}).toArray(function (err, bookingDetailsDocs) {
                            if (userDetailsDocs) {
                                if (bookingDetailsDocs.length) {
                                    temp.bookingDetails = bookingDetailsDocs;
                                    bookingDetailsDocs.forEach(function (bookDetailItems, key) {
                                        db.collection('serviceCatalog').findOne({'_id': new mongo.ObjectID(bookDetailItems.catalogId), isDeleted: 0}, function (err, spCatalogs) {
                                            db.collection('spServiceCatalog').findOne({'_id': new mongo.ObjectID(spCatalogs.serviceCategory)}, function (err, spServiceCatalogDocs) {
                                                if (spCatalogs) {
                                                    (spServiceCatalogDocs)
                                                    spCatalogs.catalogName = spServiceCatalogDocs.name;
                                                    temp.bookingDetails[key].serviceCatalgs = spCatalogs;
                                                } else {
                                                    spCatalogs.catalogName = null;
                                                    temp.bookingDetails[key].serviceCatalgs = spCatalogs;
                                                }
                                                    callback(null, temp);
                                            })
                                        })
                                    })
                                }
                            } else {
                                callback(null, null);
                            }
                        })
                    })
                })
            })
        }
    })

I tried with callback function but it not get the values of category name from mainCategory document. I also tried to get the internal fetched category name outside the forEach() but its not getting in result in temp array.

Answer 1

This may help you.

It says.. Functions are the only thing on javascript that "enclose" scope.

This means that the variable items in your inner callback function are not accessible on the outer scope.

You can define a variable in the outer scope so it will be visible to all the inner ones: