MongoDB Cheats

MongoDB Cheats

Various Cheats found on the Web

mongo           //Start Mongo
show dbs	//Show databases
use mydb	//User database named "­myd­b"
db	        //Show selected database
help	        //Get help
show collec­tion //Show collec­tions from a database

Finds - db.collection
.find()	                          //Displays documents from "­col­lec­tio­n" (first 10)
it	                          //Type "­it" to see more documents after the prev command
.find( query [, fields] )	  //Find all documents by condit­ions, with optional fields selection
.findOne( query )	          //Find one document by conditions
.find( query ) .limit( n:number ) //Find n document by conditions
.find() .pretty()	          //Format results in Mongo Shell
.find() .sort( key : 1|-1 )	  //Sort by key in ascending (1) or descending (-1) order
.find() .skip( 5 )	          //Skip 5 documents (similar to offset)

Queries
_id	                          //Search by ID
key: value	                  //Search through key-value combin­ation
{ subkey: value }	          //Search with subdoc­ument
$in : [ e1, e2, .. ]	          //Search IN Array
queries are repres­ented through JSON objects

DATABASE METHODS

  db.addUser(username, password)
  db.auth(username, password)
  db.cloneDatabase(fromhost)
  db.commandHelp(name) // returns the help for the command
  db.copyDatabase(fromdb, todb, fromhost)
  db.createCollection(name, { size : ..., capped : ..., max : ... } )
  db.currentOp() // displays the current operation in the db
  db.dropDatabase()
  db.eval(func, args) // run code server-side
  db.getCollection(cname) // same as db['cname'] or db.cname
  db.getCollectionNames()
  db.getLastError() // just returns the err msg string
  db.getLastErrorObj() // return full status object
  db.getMongo() // get the server connection object
  db.getMongo().setSlaveOk() // allow this connection to read from the nonmaster member of a replica pair
  db.getName()
  db.getPrevError()
  db.getProfilingLevel()
  db.getReplicationInfo()
  db.getSisterDB(name) // get the db at the same server as this onew
  db.killOp() // kills the current operation in the db
  db.printCollectionStats()
  db.printReplicationInfo()
  db.printSlaveReplicationInfo()
  db.printShardingStatus()
  db.removeUser(username)
  db.repairDatabase()
  db.resetError()
  db.runCommand(cmdObj) // run a database command. if cmdObj is a string, turns it into {cmdObj:1}
  db.setProfilingLevel(level) // 0=off 1=slow 2=all
  db.shutdownServer()
  db.version() // current version of the server

COLLECTION METHODS

  db.foo.count()
  db.foo.dataSize()
  db.foo.distinct( key ) // eg. db.foo.distinct( 'x' )
  db.foo.drop() // drop the collection
  db.foo.dropIndex(name)
  db.foo.dropIndexes()
  db.foo.ensureIndex(keypattern,options) // options should be an object with these possible fields: name, unique, dropDups
  db.foo.find( [query] , [fields]) // first parameter is an optional query filter.
                                   // second parameter is optional set of fields to return.
                                   // e.g. db.foo.find( { x : 77 } , { name : 1 , x : 1 } )
  db.foo.find(...).count()
  db.foo.find(...).limit(n)
  db.foo.find(...).skip(n)
  db.foo.find(...).sort(...)
  db.foo.findOne([query])
  db.foo.getDB() // get DB object associated with collection
  db.foo.getIndexes()
  db.foo.group( { key : ..., initial: ..., reduce : ...[, cond: ...] } )
  db.foo.mapReduce( mapFunction , reduceFunction , <optional params> )
  db.foo.remove(query)
  db.foo.renameCollection( newName ) // renames the collection
  db.foo.save(obj)
  db.foo.stats()
  db.foo.storageSize() // includes free space allocated to this collection
  db.foo.totalIndexSize() // size in bytes of all the indexes
  db.foo.totalSize() // storage allocated for all data and indexes
  db.foo.update(query, object[, upsert_bool, multi_record_bool])
  db.foo.validate() // SLOW
  db.foo.getShardVersion() // only for use with sharding

EXAMPLES

  Inserting Data
    > j = { name: "mongo"};
    {"name" : "mongo"}
    > t = { x : 3 };
    { "x" : 3  }
    > db.things.save(j);
    > db.things.save(t);

  Accessing Data from a Query
    var cursor = db.things.find();
    while (cursor.hasNext()) { print(tojson(cursor.next())); }

  Retrieving Data with Javascript functions
    db.things.find().forEach( function(x) { printjson(x);});

  select * from things where name="mongo"
    db.things.find({name:"mongo"}).forEach(printjson);

  select * from things where x=4
    db.things.find({x:4}).forEach(printjson);

  select j from things where x=4
    db.things.find({x:4}, {j:true}).forEach(printjson);

  order by
    db.things.find().sort({x:1})  // ascending
    db.things.find().sort({x:-1}) // descending

  limit 1
    var mongo = db.things.findOne({name:"mongo"});
    print(tojson(mongo));

  limit(x)
    db.things.find().limit(3);

  regex search
    db.things.find({x : /foo.*/i});

  search for type
    db.things.find({ x : { $type : 16 }});  // finds integer values in this field

  update users set api_token = 'snafu' where _id = "fubar";
    db.users.update( { "_id" : "fubar" }, { $set : { "api_token" : "snafu" } }, false );

  update or insert users set api_token = 'snafu' where _id = "fubar";
    db.users.update( { "_id" : "fubar" }, { $set : { "api_token" : "snafu" } }, true );

  Rename all fields in a collection
    db.users.update( {}, { $rename : {"old_field_name" : "new_field_name"}}, false, true);