Add new field to every document in a MongoDB collection

Question

How can I add a new field to every document in an existent collection   I know how to update an existing document s field but not how to add a new field to every document in a collection  How can I do this in the mongo shell

User · Accepted Answer

Same as the updating existing collection field, $set will add a new fields if the specified field does not exist.

Check out this example:

> db.foo.find()
> db.foo.insert({"test":"a"})
> db.foo.find()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "test" : "a" }
> item = db.foo.findOne()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "test" : "a" }
> db.foo.update({"_id" :ObjectId("4e93037bbf6f1dd3a0a9541a") },{$set : {"new_field":1}})
> db.foo.find()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "new_field" : 1, "test" : "a" }

EDIT:

In case you want to add a new_field to all your collection, you have to use empty selector, and set multi flag to true (last param) to update all the documents

db.your_collection.update(
  {},
  { $set: {"new_field": 1} },
  false,
  true
)

EDIT:

In the above example last 2 fields false, true specifies the upsert and multi flags.

Upsert: If set to true, creates a new document when no document matches the query criteria.

Multi: If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document.

This is for Mongo versions prior to 2.2. For latest versions the query is changed a bit

db.your_collection.update({},
                          {$set : {"new_field":1}},
                          {upsert:false,
                          multi:true})

User · Answer

To clarify  the syntax is as follows for MongoDB version 4 0 x    db collection update      set    new field   1   false true    Here is a working example adding a published field to the articles collection and setting the field s value to true   db articles update      set    published  true   false true

User · Answer

Since MongoDB version 3 2 you can use updateMany     gt  db yourCollection updateMany       set   quot someField quot    quot someValue quot

User · Answer

Pymongo 3 9   update   is now deprecated and you should use replace one    update one    or update many   instead   In my case I used update many   and it solved my issue   db your collection update many        set     new field    value     upsert False  array filters None    From documents   update many filter  update  upsert False  array filters None  bypass document validation False  collation None  session None    filter  A query that matches the documents to update   update  The modifications to apply   upsert  optional   If True  perform an insert if no documents match the filter   bypass document validation  optional   If True  allows the write to opt-out of document level validation  Default is False   collation  optional   An instance of Collation  This option is only supported on MongoDB 3 4 and above   array filters  optional   A list of filters specifying which array elements an update should apply  Requires MongoDB 3 6    session  optional   a ClientSession

User · Answer

if you are using mongoose try this after mongoose connection async     gt  await Mongoose model  quot collectionName quot   updateMany       set   newField  value

[mongodb] Add new field to every document in a MongoDB collection

Examples related to mongodb

Examples related to field

Examples related to nosql