[Java SpringBoot] How to update a document on condition

Working with Data Drivers
,
5

Hi @KamelA,

Let’s say I have these 2 docs in my collections:

[
  {
    _id: ObjectId("6214d7d015bfcf433d5b7d33"),
    name: 'factory',
    num: 3,
    workers: [ 'a', 'b', 'c' ],
    testers: [ 'a', 'b' ],
    developers: [ 'c' ],
    status: 'NOT_FULL'
  },
  {
    _id: ObjectId("6214d7ed15bfcf433d5b7d34"),
    name: 'factory',
    num: 3,
    workers: [ 'a', 'b', 'c' ],
    testers: [ 'a' ],
    developers: [ 'c' ],
    status: 'NOT_FULL'
  }
]

The first one needs a status update.

We can do it like this:

db.coll.updateMany({
  status: {$ne: "FULL"},
  $expr: { $eq: [
    {$size: "$workers"}, 
    {$add: [{$size: "$testers"}, {$size: "$developers"}]}
  ]}
},
{$set: {status: "FULL"}})

Which would work better if the status field was indexed.
This query would also be faster if the array sizes were stored (and indexed) instead of being re-calculated all the time.
It’s usually fairly easy to maintain the size of the array and the array in sync by using in the same update operation $push or $pop for the array and $inc for the size.

Cheers,
Maxime.

1 Like