MongoDB: FailedToParse: Bad characters in value

Question

mongodump command:

mongodump --host myhost.com --port 12345 --username myUsername --password PSWRD --out /opt/somepath --db myDb --collection my_collection --query "{ content_type_id: { \$not: { \$eq: db.my_type.findOne({slug: 'form_submissions'} )._id } } }" --verbose

Results in:

assertion: 16619 code FailedToParse: FailedToParse: Bad characters in value:

offset:33 of:{ content_type_id: { $not: { $eq: db.my_type.findOne({slug: 'form_submissions'} )._id } } }

Answer 1

That's not a valid query. --query must be a JSON document. Your error is in thinking that mongodump is something programmatic like the mongo shell that can evaluate the findOne and substitute the value into the query. This is not the case. You can find the _id from the result of the findOne and put it in the mongodump --query manually. Use extended JSON format for an ObjectId type, if that is the type of _id.