What is the recommended way to "create or update" a doc?

[aguynamedben]

Hi, thanks for your work on this excellent gem.

I've been going through the README and rdocs, and I'm not sure what the recommended way is to "create or update" a doc. I'm looking for something like Rails' find_or_create_by but for couchrest.

My Model

class User < ApplicationRecord
  has_many :events

  def copy_events_to_pouchdb!
    puts "Copying Events for user #{id} to pouchdb"

    server = CouchRest.new("http://localhost:5985")
    db = server.database!("events-user_#{id}")

    events.each do |event|
      puts "  Copying Event #{event.id} to pouchdb"
      doc = CouchRest::Document.new(
        _id: event.id.to_s,
        title: event.title,
      )
      db.save_doc(doc)
    end
  end
end

My Rake task

  desc "Copy all users to pouchdb-server"
  task copy_events_to_pouchdb: :environment do
    User.find_each do |user|
      user.copy_events_to_pouchdb!
    end
  end

The first time this runs, it works and the events are created as expected, but the second time it runs I get

rake aborted!
CouchRest::Conflict: 409 Conflict
/Users/ben/code/mammoth/app/models/user.rb:33:in `block in copy_events_to_pouchdb!'
/Users/ben/code/mammoth/app/models/user.rb:26:in `copy_events_to_pouchdb!'

Do I need to always go t get THEN a put? (because that would produce a _rev field for the document?) The rdocs for Database#save_doc and Document#save imply that it can create or update, but I don't see any clear-cut examples of how to do this.

Thanks again for the time you spend working on this gem.

[aguynamedben]

One method is to approximate Rails' find_or_intialize_by like this:

  def copy_events_to_pouchdb!
    puts "Copying Events for user #{id} to pouchdb"

    server = CouchRest.new("http://localhost:5985")
    db = server.database!("events-user_#{id}")

    events.each do |event|
      puts "  Copying Event #{event.id} to pouchdb"

      # First HTTP request
      doc = db.get(event.id.to_s) || CouchRest::Document.new(_id: event.id.to_s)
      doc["title"] = event.title
      # Second HTTP request
      db.save_doc(doc)
    end
  end

The downside is this requires 2 HTTP requests instead of 1.