I've been using mongo and script files like this:
$ mongo getSimilar.js I would like to pass an argument to the file:
$ mongo getSimilar.js apples And then in the script file pick up the argument passed in.
var arg = $1; print(arg); 
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7 Answers
Use --eval and use shell scripting to modify the command passed in.
mongo --eval "print('apples');"
Or make global variables (credit to Tad Marshall):
$ cat addthem.js printjson( param1 + param2 ); $ ./mongo --nodb --quiet --eval "var param1=7, param2=8" addthem.js 15 
2 Comments
Thomas
This doesn't work with mapreduce, the reduce() function doesn't have access to the params (ReferenceError: ... is not defined near ...)
Developer Marius Žilėnas
--eval is very useful. say we want to quickly change secondary to become primary in a replication set. Use a script
conf = rs.conf() conf.members.forEach( function (member) { member.priority = 0.5 } ) conf.members[memberId].priority = 1 // rs.reconfig(conf) save this script in chooseprimary.js and run with mongo --eval "var memberId=3" chooseprimary.js . memberId should be the id of the secondary you wish to become primary. Just make sure to execute mongo --eval on the Primary server. :)You can't do that, but you could put them in another script and load that first:
// vars.js msg = "apples"; and getSimilar.js was:
print(msg); Then:
$ mongo vars.js getSimilar.js MongoDB shell version: blah connecting to: test loading file: vars.js loading file: getSimilar.js apples Not quite as convenient, though.
1 Comment
Tim Fulmer
Awesome, thanks for the info! I've got a few scripts that would be a little tough to
--eval.Set a shell var:
password='bladiebla' Create js script:
cat <<EOT > mongo-create-user.js print('drop user admin'); db.dropUser('admin'); db.createUser({ user: 'admin', pwd: '${password}', roles: [ 'readWrite'] }); EOT Pass script to mongo:
mongo mongo-create-user.js 
1 Comment
conner.xyz
this does not work with 2.4. Can you point to documentation or expand on this?
2022 update:
when using mongosh you can read the execution arguments from process.argv
mongosh script.js param1 param2 // process.argv will be [.... , 'param1', param2'] the tricky bit is that mongosh will try to execute the parameters (e.g. param1 and param2) as additional scripts, but this can be prevented by ending the script using quit(). (TBH, I'm not sure it's by design / intended / documented)
1 Comment
chichilatte
How about:
param1=yourParamValue mongosh $mongoUrl script.js --quiet and access the param in javascript with process.env.param1. That works perfectly in Mac and unix. On Windows it's slightly different.I used a shell script to pipe a mongo command to mongo. In the mongo command I used an arg I passed to the shell script (i.e. i used $1):
#!/bin/sh objId=$1 EVAL="db.account.find({\"_id\" : \"$objId\"})" echo $EVAL | mongo localhost:27718/balance_mgmt --quiet 
I wrote a small utility to solve the problem for myself. With the mongoexec utility, you would be able to run the command ./getSimilar.js apples by adding the following to the beginning of your script:
#!/usr/bin/mongoexec --quiet Within the script, you can then access the arguments as args[0].
2 Comments
user764486
@Bear The instructions fail to mention that the script must be executable. If you run "sudo chmod +rx /usr/bin/mongoexec" it should work.
I solved this problem, by using the javascript bundler parcel: https://parceljs.org/
With this, one can use node environment variables in a script like:
var collection = process.env.COLLECTION; when building with parcel, the env var gets inlined:
parcel build ./src/index.js --no-source-maps The only downside is, that you have to rebuild the script every time you want to change the env vars. But since parcel is really fast, this is not really a problem imho.
