MongoDB update every document on one field

Question

I have a collected named foo hypothetically   Each instance of foo has a field called lastLookedAt which is a UNIX timestamp since epoch  I d like to be able to go through the MongoDB client and set that timestamp for all existing documents  about 20 000 of them  to the current timestamp   What s the best way of handling this

User · Accepted Answer

Regardless of the version  for your example  the  lt update gt  is       set    lastLookedAt  Date now     1000        However  depending on your version of MongoDB  the query will look different  Regardless of version  the key is that the empty condition    will match any document  In the Mongo shell  or with any MongoDB client    version    3 2   db foo updateMany       lt update gt          is the condition  the empty condition matches any document    3 2    version    2 2   db foo update       lt update gt     multi  true           is the condition  the empty condition matches any document   multi  true  is the  update multiple documents  option    version  lt  2 2    db foo update       lt update gt   false  true         is the condition  the empty condition matches any document  false is for the  upsert  parameter true is for the  multi  parameter  update multiple records

User · Answer

This code will be helpful for you          Model update                type    newuser                            set                    email   abc gmail com                   phoneNumber  0123456789                                         multi  true                    function err  result                console log result               console log err

User · Answer

You can use updateMany   methods of mongodb to update multiple document Simple query is like this db collection updateMany filter  update  options   For more doc of uppdateMany read here As per your requirement the update code will be like this  User updateMany   quot created quot   false     quot  set quot    quot created quot   true      here you need to use  set because you just want to change created from true to false  For ref  If you want to change entire doc then you don t need to use  set

User · Answer

I have been using MongoDB  NET driver for a little over a month now  If I were to do it using  NET driver  I would use Update method on the collection object  First  I will construct a query that will get me all the documents I am interested in and do an Update on the fields I want to change  Update in Mongo only affects the first document and to update all documents resulting from the query one needs to use  Multi  update flag  Sample code follows     var collection   db GetCollection  Foo    var query   Query GTE  No   1      need to construct in such a way that it will give all 20K   docs  var update   Update Set  timestamp   datetime UtcNow   collection Update query  update  UpdateFlags Multi

[mongodb] MongoDB: update every document on one field

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