queries in mongodb command line -

i want query list cities in specific state populations between 6000 , 8000. in big data. :

{ "_id" : "01564", "city" : "sterling", "loc" : [ -71.775192, 42.435351 ], "pop" : 6481, "state" : "ma" } { "_id" : "01566", "city" : "sturbridge", "loc" : [ -72.084233, 42.112619 ], "pop" : 7001, "state" : "ma" } { "_id" : "01568", "city" : "west upton", "loc" : [ -71.608014, 42.173275 ], "pop" : 4682, "state" : "ma" } { "_id" : "01569", "city" : "uxbridge", "loc" : [ -71.632869, 42.074426 ], "pop" : 10364, "state" : "ma" } 

i want return cities in massachusetts let above example. how can ? t tried :

 >db.zipcodes.aggregate( [    { $group: { _id: "$city",statename:"$state", totalpop: { $sum: "$pop" } } }, { $match: { totalpop: { $gte: 1000  , $lte : 2000 },statename:"massachusetts" } } ] ); 

and got error below:

 aggregate failed @ error (<anonymous>) @ doassert (src/mongo/shell/assert.js:11:14) @ function.assert.commandworked (src/mongo/shell/assert.js:254:5) @ dbcollection.aggregate (src/mongo/shell/collection.js:1278:12) @ (shell):1:13 @ src/mongo/shell/assert.js:13 

you not need use aggregation framework.

db.zipcodes.find({    state: 'ma',    pop: {      $gte: 6000,      $lte: 8000    } }, {city: 1}) 

if need name of cities (unique) can use distinct

db.zipcodes.distinct('city', {    state: 'ma',    pop: {      $gte: 6000,      $lte: 8000    } }) 

or use foreach