Inconsistent issue in pushing values to empty arrays about migrate-mongo HOT 2 CLOSED

This is not a bug. You are not using callbacks correctly.

db.collection('sample').update({name: 'sample1'}, {$push: {an_array_field: "test val 1"}}, next)
db.collection('sample').update({name: 'sample1'}, {$push: {an_array_field: "test val 2"}}, next)
db.collection('sample').update({name: 'sample1'}, {$push: {an_array_field: "test val 3"}}, next)

==> you call the callback (next in this case) 3 times instead of 1 time.
If you use callbacks, you must call the callback only once.

There are several options to fix it:

1. Transform your script so it uses async and await instead of callbacks.
2. Transform your script so it uses promises instead of callbacks.
3. If you really want to keep using callbacks: refactor your code so the next callback is called when all I/O operations to mongodb are done. To avoid callback hell: use a library like async.

I suggest option 1. I would avoid option 3.

from migrate-mongo.

ok, thank you for the tip

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