Comparing mongoose id and strings

Question

I have a node js application that pulls some data and sticks it into an object  like this   var results   new Object     User findOne query  function err  u        results userId   u  id      When I do an if then based on that stored ID  the comparison is never true   if  results userId    AnotherMongoDocument  id        console log  This is never true        When I do a console log of the two id s  they match exactly   User id  4fc67871349bb7bf6a000002 AnotherMongoDocument id  4fc67871349bb7bf6a000002   I am assuming this is some kind of datatype problem  but I m not sure how to convert results userId to a datatype that will result in the above comparison being true and my outsourced brain  aka Google  has been unable to help

User · Answer

According to the above i found three ways to solve the problem    AnotherMongoDocument  id toString   JSON stringify AnotherMongoDocument  id  results userId equals AnotherMongoDocument  id

User · Answer

ObjectIDs are objects so if you just compare them with    you re comparing their references   If you want to compare their values you need to use the ObjectID equals method   if  results userId equals AnotherMongoDocument  id

User · Answer

The accepted answers really limit what you can do with your code  For example  you would not be able to search an array of Object Ids by using the equals method  Instead  it would make more sense to always cast to string and compare the keys    Here s an example answer in case if you need to use indexOf   to check within an array of references for a specific id  assume query is a query you are executing  assume someModel is a mongo model for the id you are looking for  and finally assume results idList is the field you are looking for your object id in   query exec function err results      var array   results idList map function v   return v toString           var exists   array indexOf someModel  id toString     gt   0     console log exists

User · Answer

converting object id to string using toString   method  will do the job

User · Answer

The three possible solutions suggested here have different use cases    Use  equals when comparing ObjectID on two mongoDocuments like this  results userId equals AnotherMongoDocument  id  Use  toString   when comparing a string representation of ObjectID to an ObjectID of a mongoDocument  like this  results userId     AnotherMongoDocument  id toString

User · Answer

I faced exactly the same problem and i simply resolved the issue with the help of JSON stringify   as follow -      if  JSON stringify results userId      JSON stringify AnotherMongoDocument  id             console log  This is never true

User · Answer

Mongoose uses the mongodb-native driver  which uses the custom ObjectID type  You can compare ObjectIDs with the  equals   method  With your example  results userId equals AnotherMongoDocument  id   The ObjectID type also has a toString   method  if you wish to store a stringified version of the ObjectID in JSON format  or a cookie   If you use ObjectID   require  mongodb   ObjectID  requires the mongodb-native library  you can check if results userId is a valid identifier with results userId instanceof ObjectID   Etc

[node.js] Comparing mongoose _id and strings

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