CODEWITHSUNDEEP
ruby-on-railsjsonpostgresqljsonb
CafeHey
CafeHey

Reputation: 5800

How to update different json (jsonb) attributes asynchronously with rails and postgres?

I have a large json object stored in a postgres table column, an example of the schema is like this:

create_table “document” do |t|
    t.jsonb “data”, default: []
end

At the moment I’m updating json in the column like so:

# find document in rails then…
doucment.data[‘some_attribute’][2][‘another_attribute’] = 100
doucment.save

However I write this json attribute many times and sometimes data becomes lost because if two calls are writing it at the same time, then the whole object will be saved or over written with the current objects old data.

For example if there’s two different saves going through at the same with the following

Save 1:

doucment.data[‘some_attribute’][2][‘another_attribute’] = 100
doucment.save

Save 2:

doucment.data[‘some_attribute’][2][‘different_attribute’] = 200
doucment.save

then either one of the attributes data will be lost because the other one will save it’s json but with old data that hasn’t been refreshed yet.

What is the best way to go about making both calls save the new data correctly.

Is there any json method that can just go in and update one attribute, like update_attribute but for a jsonb attribute?

Upvotes: 5

Views: 3772

Answers (2)

Andrew Rozhenko
Andrew Rozhenko

Reputation: 526

This occurs because you update the document asynchronously, it has nothing to do with the attribute being a json.

The right thing to do here would be to lock the model before modifying it, that way it won't be overridden, but updated one step at a time.

Try the following:

Document.lock.find_by(...)

ActiveRecord::Locking::Pessimistic

Upvotes: 0

demir
demir

Reputation: 4709

Postgresql has the jsonb_set method. You can update your model using this method.

With this code, the record is updated in a single query:

Document.where(id: document.id).update_all(
  "data = jsonb_set(data, '{some_attribute,2,another_attribute}', to_json(#{your_int_value}::int)::jsonb)"
)

Related postgresql document

Answer that helps me

Upvotes: 5

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