How to drop all databases in MongoDB?

You can use the getDBNames() method in the mongo shell.

This method must be called from the Mongo() instance. Unfortunately I don't think the getDBNames() method is documented.

After getting the database names, you can then loop through them to drop the unwanted ones using something like:

Mongo().getDBNames().forEach(function(x) {
  // loop through all the database names
  if (['admin', 'config', 'local'].indexOf(x) < 0) {
    // drop database if it's not admin, config, or local
    Mongo().getDB(x).dropDatabase();
  }
})

For example:

> show dbs
admin   0.000GB
config  0.000GB
local   0.001GB
test    0.000GB
test2   0.000GB
test3   0.000GB

> Mongo().getDBNames().forEach(function(x) {
...   if (['admin', 'config', 'local'].indexOf(x) < 0) {
...     Mongo().getDB(x).dropDatabase();
...   }
... })

> show dbs
admin   0.000GB
config  0.000GB
local   0.001GB

I fixed this issue using solution from this tutorial

I ran this code in my mongo shell:

var dbs = db.getMongo().getDBNames()
for(var i in dbs){
    db = db.getMongo().getDB( dbs[i] );
    if (db.getName() !== 'admin' && db.getName() !== 'local' && db.getName() !== 'config') 
    {
        print( "dropping db " + db.getName() );  
        db.dropDatabase();
    }
}