mongodb - How do I update a collection using multiple _id's? -

i trying update collection based on multiple _id's.

i recieve _id's in array format via session.get() below:

 var selectedid = session.get('selecteditemidset');   console.log("selectedid array contents are: "+selectedid);  

the code above ensures selectedid array exists , yields:

selectedid array contents are: lzjka8s3wynwhakze,ikrbcdutthrwkecuv

the query below:

buylist.find({_id:{ "$in": selectedid} }).fetch();  

successfully yeilds 2 objects!

now area having issues with, how update collection these 2 _id's

i have tried below code:

var postedarray = [{postedby: meteor.user()._id }]; buylist.update(_id: selectedid, {$set: {wishlistarray: postedarray} }); 

...but error message: uncaught error: mongo selector can't array.(…)

any appreciated.

use same selector in update have done find + specify multi: true option:

buylist.update({ // selector   _id: {     "$in": selectedid   } }, { // modifier   $set: {     wishlistarray: postedarray   } }, { // options   multi: true }); 

note 2 documents updated same modifier.