MongoDB  1.8.5
Public Member Functions | Public Attributes
mongo::Query Class Reference

Represents a Mongo query expression. More...

#include <dbclient.h>

List of all members.

Public Member Functions

 Query (const BSONObj &b)
 Query (const string &json)
 Query (const char *json)
Querysort (const BSONObj &sortPattern)
 Add a sort (ORDER BY) criteria to the query expression.
Querysort (const string &field, int asc=1)
 Add a sort (ORDER BY) criteria to the query expression.
Queryhint (BSONObj keyPattern)
 Provide a hint to the query.
Queryhint (const string &jsonKeyPatt)
QueryminKey (const BSONObj &val)
 Provide min and/or max index limits for the query.
QuerymaxKey (const BSONObj &val)
 max is exclusive
Queryexplain ()
 Return explain information about execution of this query instead of the actual query results.
Querysnapshot ()
 Use snapshot mode for the query.
Querywhere (const string &jscode, BSONObj scope)
 Queries to the Mongo database support a $where parameter option which contains a javascript function that is evaluated to see whether objects being queried match its criteria.
Querywhere (const string &jscode)
bool isComplex (bool *hasDollar=0) const
 if this query has an orderby, hint, or some other field
BSONObj getFilter () const
BSONObj getSort () const
BSONObj getHint () const
bool isExplain () const
string toString () const
 operator string () const

Public Attributes

BSONObj obj

Detailed Description

Represents a Mongo query expression.

Typically one uses the QUERY(...) macro to construct a Query object. Examples: QUERY( "age" << 33 << "school" << "UCLA" ).sort("name") QUERY( "age" << GT << 30 << LT << 50 )


Member Function Documentation

Query & mongo::Query::explain ( )

Return explain information about execution of this query instead of the actual query results.

Normally it is easier to use the mongo shell to run db.find(...).explain().

Query & mongo::Query::hint ( BSONObj  keyPattern)

Provide a hint to the query.

Parameters:
keyPatternKey pattern for the index to use. Example: hint("{ts:1}")
Query & mongo::Query::minKey ( const BSONObj val)

Provide min and/or max index limits for the query.

min <= x < max

Query & mongo::Query::snapshot ( )

Use snapshot mode for the query.

Snapshot mode assures no duplicates are returned, or objects missed, which were present at both the start and end of the query's execution (if an object is new during the query, or deleted during the query, it may or may not be returned, even with snapshot mode).

Note that short query responses (less than 1MB) are always effectively snapshotted.

Currently, snapshot mode may not be used with sorting or explicit hints.

Query & mongo::Query::sort ( const BSONObj sortPattern)

Add a sort (ORDER BY) criteria to the query expression.

Parameters:
sortPatternthe sort order template. For example to order by name ascending, time descending: { name : 1, ts : -1 } i.e. BSON( "name" << 1 << "ts" << -1 ) or fromjson(" name : 1, ts : -1 ")
Query& mongo::Query::sort ( const string &  field,
int  asc = 1 
) [inline]

Add a sort (ORDER BY) criteria to the query expression.

This version of sort() assumes you want to sort on a single field.

Parameters:
asc= 1 for ascending order asc = -1 for descending order
Query & mongo::Query::where ( const string &  jscode,
BSONObj  scope 
)

Queries to the Mongo database support a $where parameter option which contains a javascript function that is evaluated to see whether objects being queried match its criteria.

Use this helper to append such a function to a query object. Your query may also contain other traditional Mongo query terms.

Parameters:
jscodeThe javascript function to evaluate against each potential object match. The function must return true for matched objects. Use the this variable to inspect the current object.
scopeSavedContext for the javascript object. List in a BSON object any variables you would like defined when the jscode executes. One can think of these as "bind variables".

Examples: conn.findOne("test.coll", Query("{a:3}").where("this.b == 2 || this.c == 3")); Query badBalance = Query().where("this.debits - this.credits < 0");


The documentation for this class was generated from the following files: