// SERVER-393 Test exists with various empty array and empty object cases.

t = db.jstests_exists9;
t.drop();

// Check existence of missing nested field.
t.save( {a:{}} );
assert.eq( 1, t.count( {'a.b':{$exists:false}} ) );
assert.eq( 0, t.count( {'a.b':{$exists:true}} ) );

// With index.
t.ensureIndex( {'a.b':1} );
assert.eq( 1, t.find( {'a.b':{$exists:false}} ).hint( {'a.b':1} ).itcount() );
assert.eq( 0, t.find( {'a.b':{$exists:true}} ).hint( {'a.b':1} ).itcount() );

t.drop();

// Check that an empty array 'exists'.
t.save( {} );
t.save( {a:[]} );
assert.eq( 1, t.count( {a:{$exists:true}} ) );
assert.eq( 1, t.count( {a:{$exists:false}} ) );

// With index.
t.ensureIndex( {a:1} );
assert.eq( 1, t.find( {a:{$exists:true}} ).hint( {a:1} ).itcount() );
assert.eq( 1, t.find( {a:{$exists:false}} ).hint( {a:1} ).itcount() );
assert.eq( 1, t.find( {a:{$exists:false}} ).hint( {a:1} ).explain().nscanned );

t.drop();

// Check that an indexed field within an empty array does not exist.
t.save( {a:{'0':1}} );
t.save( {a:[]} );
assert.eq( 1, t.count( {'a.0':{$exists:true}} ) );
assert.eq( 1, t.count( {'a.0':{$exists:false}} ) );

// With index.
t.ensureIndex( {'a.0':1} );
assert.eq( 1, t.find( {'a.0':{$exists:true}} ).hint( {'a.0':1} ).itcount() );
assert.eq( 1, t.find( {'a.0':{$exists:false}} ).hint( {'a.0':1} ).itcount() );