Saving the result of a MongoDB query

Question

When doing a research in mongo shell I often write quite complex queries and want the result to be stored in other collection. I know the way to do it with .forEach():

db.documents.find(query).forEach(function(d){db.results.insert(d)})

But it's kind of tedious to write that stuff each time. Is there a cleaner way? I'd like the syntax to be something like db.documents.find(query).dumpTo('collectionName').

Answer 1

Here's a solution I'll use: db.results.insert(db.docs.find(...).toArray())

There is still too much noise, though.

UPD: There is also an option to rewrite find using aggregation pipeline. Then you can use $out operator.

Answer 2

It looks like you are doing your queries from the mongo shell, which allows you to write code in javascript. You can assign the result of queries to a variable:

result = db.mycollection.findOne(my_query)

And save the result to another collection:

db.result.save(result)

You might have to remove the _id of the result if you want to append it to the result collection, to prevent a duplicate key error

Edit:

db.mycollection.findOne({'_id':db.mycollection.findOne()['_id']})
db.foo.save(db.bar.findOne(...))

If you want to save an array, you can write a javascript function. Something like the following should work (I haven't tested it):

function save_array(arr) {
    for(var i = 0; i < arr.length; i++) {
        db.result.save(arr[i])
    }
}

...

result = db.mycollection.find(...)
save_array(result)

If you want the function to be available every time you start mongo shell, you can include it in your .mongorc.js file