javascript - Update a value for existing documents with Mongoose? -

i have document field 'position', used sorting results via angular loop on frontend.

right now, schema accurately auto-incrementing new documents lack 'position', , storing new documents have form-field-entered position.

when inserting item existing 'position' value, want move every record down. wrote javascript logic this, doesn't hit else if..

// load mongoose since need define schema , model var mongoose = require('mongoose');  var itemschema = mongoose.schema({     title : string,     position: number });  // before validation starts, number of items counted..afterwards, position set itemschema.pre("validate", function(next) {      var doc = this;      // if 'position' not filled in, fill in..not using !position because 0 might valid value     if(typeof doc.position !== "number") {         // count number of items *         // use mongoose.model fetch model because model not compiled yet         mongoose.model("item").count(function(err, num) {             // if there error, pass next()             if(err)                 return next(err);              // set position, call next();             doc.position = num;             return next();         });     } else if(doc.position == "number") {          console.log('yes, number');          // check if there existing document same position         // use mongoose.model fetch model because model not compiled yet         mongoose.model("item").where({_id: {$ne: doc._id}, position: doc.position}).count( function (err, count) {              // if there error, pass next()             if(err)                 return next(err);              // if there doc same position, execute update move down $gte docs             if(count > 0) {                 // use mongoose.model fetch model because model not compiled yet                 mongoose.model("item").update({position: {$gte: doc.position}}, {position: {$inc: 1}}, {multi: 1}, function(err, numaffected) {                      console.log(numaffected);                      // call next() (with or without error)                     next(err);                 });              } else {                 //  there no docs need move down, call next()                 next();             }         });     } else {         //  there no need count or update positions, call next()         next();     } });  module.exports = mongoose.model('item', itemschema);