Sails.js: Nested MongoDB queries

问题

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.

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){

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
            });
        });
    });
};

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

回答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
        }); 


    });
  });
}

来源：https://stackoverflow.com/questions/32058797/sails-js-nested-mongodb-queries

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javascript

node.js

sails.js

waterline

sails-mongo