CODEWITHSUNDEEP
mongodbsubdocumentfindandmodify
Glenn McMillen
Glenn McMillen

Reputation: 13

mongo db add subdocuments from another collection

I have two collections awards teams have won and a list of teams. I want to ETL the whole of awards into the other (teams) as subdocuments with some minor transformations, but I only get one subdocument from the awards into teams.

Here is the code I used. Teams has a unique index on number and looks like the final document minus the accolade subdocument. However only one accolade subdocument is being added in the array. What am I missing?

db.awardout.find().forEach(function(award_team){
if(award_team != null)
{
db.teams.findAndModify(
{
   query: {number: award_team.team},
   update: { $set: {accolades: [ {sku: award_team.sku, acc_category: "Award", acc_name: award_team.name }] } },
   upsert: true,
   });
   }
   });

Sample awards (teams can win multiple awards and the accolades is to be the collection of awards to aggregate on later):

/* 18 */
{
  "_id" : ObjectId("552077289ad9c19e809965de"),
  "sku" : "RE-VRC-14-0110",
  "name" : "Tournament Finalists (VRC/VEXU)",
  "team" : "44",
  "qualifies" : [],
  "order" : "1"
}
/* 35 */
{
  "_id" : ObjectId("552077289ad9c19e809965ef"),
  "sku" : "RE-VRC-14-0110",
  "name" : "Robot Skills Winner (VRC/VEXU)",
  "team" : "44",
  "qualifies" : [],
  "order" : "4"
}

here is what teams turns into with only one accolade added:

{
  "_id" : ObjectId("552071f69ad9c19e80996432"),
  "program" : "VRC",
  "robot_name" : "Fred VII",
  "organisation" : "Green Egg Robotics",
  "region" : "Massachusetts",
  "country" : "United States",
  "number" : "44",
  "team_name" : "Green Egg Robotics",
  "city" : "Oakham",
  "grade" : "High School",
  "is_registered" : "0",
  "accolades" : [{
      "sku" : "RE-VRC-14-0110",
      "acc_category" : "Award",
      "acc_name" : "Think Award (VRC/VEXU)"
    }]
}

I would have expected two accolades to be added into the array. Do I need to carry the award object id into the teams subdocument?

Upvotes: 1

Views: 733

Answers (1)

ced-b
ced-b

Reputation: 4065

If you just do $set it will simply replace the array that is currently there with the one you are putting there. So you have to do a $push:

 { $push: {accolades: {sku: award_team.sku, acc_category: "Award", acc_name: award_team.name } } }

This will insert a new document into the Array.

Full doc: http://docs.mongodb.org/manual/reference/operator/update/push/

Upvotes: 1

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