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NestedSetsReference_operating_addnewnode.js
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NestedSetsReference_operating_addnewnode.js
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use TreeMongo;
//assume, we want to add LG node under Electronics
//new node would have left value of 24, affecting all remaining left values according to traversal rules
// and will have right value of 25, affecting all remaining right values including root one.
//take next node in traversal tree
var followingsibling = db.categoriesNSO.findOne({_id:"Cell_Phones_and_Accessories"});
//new node will have left value of the following sibling and right value - incremented by two following sibling's left one
var newnode = {_id:'LG', left:followingsibling.left,right:followingsibling.left+1, parent:followingsibling.parent}
//now we have to create the place for the new node
//update affects right values of all ancestor nodes
//3th and 4th parameters: false stands for upsert=false and true stands for multi=true
db.categoriesNSO.update({right:{$gt:followingsibling.right}},{$inc:{right:2}}, false, true)
//and affects all nodes that remain for traversal
db.categoriesNSO.update({left:{$gte:followingsibling.left}, right:{$lte:followingsibling.right}},{$inc:{left:2, right:2}}, false, true)
// ready to insert
db.categoriesNSO.insert(newnode)
exit
/*
+-Electronics (1,46)
+---Cameras_and_Photography (2,13)
+------Digital_Cameras (3,4)
+------Camcorders (5,6)
+------Lenses_and_Filters (7,8)
+------Tripods_and_supports (9,10)
+------Lighting_and_studio (11,12)
+----Shop_Top_Products (14,23)
+------IPad (15,16)
+------IPhone (17,18)
+------IPod (19,20)
+------Blackberry (21,22)
+----LG (24,25)
+----Cell_Phones_and_Accessories (26,45)
+------Cell_Phones_and_Smartphones (27,38)
+---------Nokia (28,29)
+---------Samsung (30,31)
+---------Apple (32,33)
+---------HTC (34,35)
+---------Vyacheslav (36,37)
+-------Headsets (39,40)
+-------Batteries (41,42)
+-------Cables_And_Adapters (43,44) */