Every once in a while, I need to give a non-technical user (like a business analyst) data residing in MongoDB; consequently, I export the target data as a CSV file (which they can presumably slice and dice once they import it into Excel or some similar tool). Mongo has a handy export utility that takes a bevy of options, however, there is an outstanding bug and some general confusion as to how to properly export data in CSV format.
Accordingly, if you need to export some specific data from MongoDB into CSV format, here’s how you do it. The key parameters are connection information to include authentication, an output file, and most important, a list of fields to export. What’s more, you can provide a query in escaped JSON format.
You can find the
mongoexport utility in your Mongo installation
bin directory. I tend to favor verbose parameter names and explicit connection information (i.e. rather than a URL syntax, I prefer to spell out the host, port, db, etc directly). As I’m targeting specific data, I’m going to specify the collection; what’s more, I’m going to further filter the data via a query.
ObjectId’s can be referenced via the
$oid format; furthermore, you’ll need to escape all JSON quotes. For example, if my query is against a
users collection and filtered by
account_id (which is an
ObjectId), the query via the
mongo shell would be:
Via the command line à la
monogexport, this translates to:
Finally, if you want to only export a portion of the fields in a
user document, for example,
created_at, you need to provide them via the
fields parameter like so:
Putting it all together yields the following command:
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Of course, you can throw this into a bash script and parameterize the
fields, output file, and query with bash’s handy
$2, etc variables.