Sails.js: Nested MongoDB queries

Question

I am using Sails v0.11 and am developing an standalone importer script in order to import data to mongoDB and - that is now the not-working part - build the associations between the models.

For this process I introduced temporary helper properties in the models in order to find the associated records and replace them by in real MongoDB _ids.

1. The script starts Sails in order to be able use its features (waterline, etc.):

   var app = Sails();
   app.load({
     hooks: { grunt: false },
     log: { level: 'warn' }
   
   }, function sailsReady(err){
   

2. processUsers() finds all users and their _ids and iterates over them to invoke a second function addOrgsToOneUser()

   var processUsers = function() {
   
       // Iterate through all users in order to retrieve their _ids and 
       app.models['user'].native(function(err, collection) {
           collection.find({}, projectionOrgInUser).toArray(function (err, users) {  
   
               Async.eachSeries(users, function (user, next){
   
   //                         prepare userInOrgs
   
                   whereUserInOrg = { orgId: { $in: userInOrgs } };
   
                   //This is invoking 
                   addOrgsToOneUser(user, whereUserInOrg);
   
                   next();
                   }, function afterwards (err) {
   
                       if (err) {
                         console.error('Import failed, error details:\n',err);
                         return process.exit(1);
                       }
   
                       console.log("done");
                       return process.exit(0); // This returns too early, not executing the addOrgsToOneUser
               });
           });
       });
   };
   

3. addOrgsToOneUser() finds all orgs belonging to THIS user and updates then the orgs array property of THIS user

   var addOrgsToOneUser = function(user, whereUserInOrg) {
   
       var projectionUserInOrg = "...";
   
       // Find all orgs that this user is associated to and store it in inOrgs
       app.models['org'].native(function(err, collection) {
           collection.find(whereUserInOrg, projectionUserInOrg).toArray(function (err, orgs) {
   
               // prepare inOrgs which is needed for updating
   
               //update user to have an updated orgs array based on inOrgs. 
               app.models['user'].update({'id' : user._id.toString()}, {'orgs': inOrgs}).exec(function afterwards(err, updated){                
                   console.log('Updated user ' + user._id.toString() + ' to be in their orgs');
               }); 
   
   
           });
       });
   }
   

Problem:

• Process.exit(0) is called before the query/update of saddOrgsToOneUser() has completed. It behaves as expected if saddOrgsToOneUser() contains just a console.log for instance, but queries are triggered ansynchronously of course.
• In case I comment out Process.exit(0), the script never stops, but the queries are executed as intented.
• As the script will have further nested queries, I need a better approach to this as manually kill this script ...
• How is nesting queries and iterating over their results done properly?

Thank you very much, Manuel

Answer 1

addOrgsToOneUser is asynchronous. next() needs to be called after everything is done inside addOrgsToOneUser. The way I would do it is to pass in a callback (next) and call it when everything is done. So the call is

addOrgsToOneUser(user, whereUserInOrg, next);

and the addOrgsToOneUser will have an extra argument:

var addOrgsToOneUser = function(user, whereUserInOrg, callback) {

  var projectionUserInOrg = "...";

  // Find all orgs that this user is associated to and store it in inOrgs
  app.models['org'].native(function(err, collection) {
    collection.find(whereUserInOrg, projectionUserInOrg).toArray(function (err, orgs) {

        // prepare inOrgs which is needed for updating

        //update user to have an updated orgs array based on inOrgs. 
        app.models['user'].update({'id' : user._id.toString()}, {'orgs': inOrgs}).exec(function afterwards(err, updated){                
            console.log('Updated user ' + user._id.toString() + ' to be in their orgs');

            callback();  // your original next() is called here
        }); 


    });
  });
}