CODEWITHSUNDEEP
rubymany-to-manymongoid
o..o
o..o

Reputation: 1921

Mongoid - remove entity from M:N collection but not delete it

I need to remove related entity from collection. So for example I have M:N relation: project which has multiple users (and users can have multiple projects).

How can I remove user from project, but do not delete him?

# this removes user from project, but also deletes user
project.users.find(id: user._id).remove

Thanks

Upvotes: 0

Views: 39

Answers (1)

iskvmk
iskvmk

Reputation: 392

Let's say we have band and it has multiple tags:

band = Band.all[1]
=> #<Band _id: 599d2c8a9d1fa2c5498024cc, name: "test_band", tag_ids: [BSON::ObjectId('599d2c8a9d1fa2c5498024cd'), BSON::ObjectId('599d2c8a9d1fa2c5498024ce'), BSON::ObjectId('599d2c8a9d1fa2c5498024cf')]>

Then if we try to delete one of related tag objects:

band.tags.delete(Tag.find(id: '599d2c8a9d1fa2c5498024cd')
...
MONGODB | localhost:27017 | test_development.update | SUCCEEDED | 0.000634s
=> #<Tag _id: 599d2c8a9d1fa2c5498024cd, name: "test_tag1", band_ids: []>

It will be removed from band.tags array:

irb(main):088:0> band
=> #<Band _id: 599d2c8a9d1fa2c5498024cc, name: "test", tag_ids: [BSON::ObjectId('599d2c8a9d1fa2c5498024ce'), BSON::ObjectId('599d2c8a9d1fa2c5498024cf')]>

But that Tag still present as object:

Tag.find(id: '599d2c8a9d1fa2c5498024cd')
=> #<Tag _id: 599d2c8a9d1fa2c5498024cd, name: "test_tag1", band_ids: []>

Upvotes: 1

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