使用nodejs mongodb驱动程序和async.js在mongodb中插入多个记录

Question

Currently I am facing a callback hell while trying to execute a number of entries into mongodb with nodejs driver. There are certain tasks that should be performed only if all the records (in array) are inserted. I checked out the async.each method but the main issue with this is that it will invoke the callback if an error is encountered. Hence the rest of the items in collection won't be processed.

So what is the correct way to deal with this kind of problem with async.js?

PS: Please an example would be very helpful as I am just starting out with async.js and there are very less(if at all) examples to use this for batch inserts into mongodb using the api.

Answer 1

Let's describe the problem.

1. You have an iteration based flow with some library (example.: AsyncJS)
2. Async Flow can be interrupted at some iteration
3. You want to be sure all the operatiosn in MongoDB are correctly stored or maybe take a future decision if that operation should happen or no

In this case i can suggest you to use Bulk Operation

 // array of operations
 let batch = yourCollection.initializeUnorderedBulkOp();

 async.each (yourArrayToIterate, function (item, next) {
     // add some Operation that will be execute lated
     batch.insert({firstName:"Daniele"});
     batch.find({firstName: "Daniele"}).updateOne({$set: {lastName:"Tassone"}});
     // other code to do...some Old Library
       try {
         someOldLibrary.doSomethingThatCanCreateAnExpection();
      } catch (e) {
         //some error happen
      }
     // more modern approach with New Library
      someNewLibrary
       .then(function (result){
       })
       .catch(function (err) {
           // some error happen
       }

 }, function (err, result) {

      // Flow is now completed, take a decision
     if (err) {
       // do nothing, maybe?
     } else {
        // execute all the Ordered Bulk 
        batch.execute().then(function(executionResult) {
            // done, you can 
        });
     }
 });

Some Note: 1) BulkOperation can be Ordered and UnOrdered. UnOrdered perform better and continue to work even if some error happen 2) Ordered is performed sequentially and if some error happen MongoD will not continue to the next element in the Bulk.

Documentation: http://mongodb.github.io/node-mongodb-native/2.0/api/Collection.html#initializeOrderedBulkOp