mongo shell does not output result of command when executing a javascript file

[Martin Lichtin]

For some reason, the mongo shell does not output the result of the command when a Javascript file is executed:

$ echo "db.stats()" >db-stats.js
$ mongo -u user -p pass db db-stats.js
MongoDB shell version: 3.0.3
connecting to: db
$

There's no output or any indication of how it went, as far as I can see.
Is there a way to improve this?

For example, when I run mongo shell semi-interactively, then I see the result:

$ echo "db.stats()" |  mongo -u user -p pass db
MongoDB shell version: 3.0.3
connecting to: db
{
        "ok" : 0,
        "errmsg" : "not authorized on db to execute command { dbstats: 1.0, scale: undefined }",
        "code" : 13
}
bye

[acveer]

It looks like it does print fine as I see the ok:1 and err message.

Also add 'use $databaseName;' to the .js file before calling db.stats().

show dbs; //showdbs.js file

$mongo < showdbs.js

MongoDB shell version: 3.0.4

connecting to: test

Northwind      0.078GB

bye

[Martin Lichtin]

Yes, but don't use it the same way. It works when providing the Javascript as stdin.
But when providing the Javascript file as an argument to mongo, then it doesn't.
In your case, try

mongo showdbs.js

and I bet you don't see the expected output.

[Stephen Steneker]

On Monday, 22 June 2015 17:34:47 UTC+10, Martin Lichtin wrote:

Yes, but don't use it the same way. It works when providing the Javascript as stdin.
But when providing the Javascript file as an argument to mongo, then it doesn't.

Hi Martin,

There are some differences in running a script via the command line vs the interactive mode of the mongo shell:
 http://docs.mongodb.org/manual/tutorial/write-scripts-for-the-mongo-shell/#differences-between-interactive-and-scripted-mongo

In particular, the interactive shell automatically prints the results of operations whereas you need to intentionally request this for a command line script.

If you wrap your command in the JS file with explicit printjson() or print(), you should see the output.

For example, db-stats.js would contain:

  printjson(db.stats())

Regards,

Stephen

[Martin Lichtin]

That's it, thanks!