Searching across multiple models produces an exception

[adambutler]

Describe the bug

Searching across multiple indexes is producing an unexpected error:

Searchkick.search("*", models: [CommunityMember, User]).results

Produces:

Searchkick::Error: Unknown model for index: community_members_20240723145721041. Pass the `models` option to the search method.
from /Users/adambutler/.asdf/installs/ruby/3.1.4/lib/ruby/gems/3.1.0/gems/searchkick-5.3.1/lib/searchkick/results.rb:237:in `block in with_hit_and_missing_records'

The problem seems to be in Searchkick::Results#with_hit_and_missing_records. You can see that options[:index_mapping] contains two keys :community_members and :users:

options[:index_mapping]
=> {:community_members=>
  [CommunityMember(id: integer, community_id: integer, user_id: integer)],
 :users=>
  [User(id: integer, email: string)]}

However index_alias is "community_members" not :community_members thus this line unexpectedly produces an empty array.

Array((options[:index_mapping] || {})[index_alias])
=> []

To reproduce
Use this code to reproduce when possible:

⚠️ Sorry I wasn't able to get bundler/inline working in my dev environment. I will come back to this later if needed.

require "bundler/inline"

gemfile do
  source "https://rubygems.org"

  gem "activerecord", require: "active_record"
  gem "activejob", require: "active_job"
  gem "sqlite3"
  gem "searchkick", git: "https://github.com/ankane/searchkick.git"
  # uncomment one
  # gem "elasticsearch"
  # gem "opensearch-ruby"
end

puts "Searchkick version: #{Searchkick::VERSION}"
puts "Server version: #{Searchkick.server_version}"

ActiveRecord::Base.establish_connection adapter: "sqlite3", database: ":memory:"
ActiveJob::Base.queue_adapter = :inline

ActiveRecord::Schema.define do
  create_table :products do |t|
    t.string :name
  end
end

class Product < ActiveRecord::Base
  searchkick
end

Product.reindex
Product.create!(name: "Test")
Product.search_index.refresh
p Product.search("test", fields: [:name]).response

Additional context
Add any other context.

[ankane]

Hi @adambutler, please use the bug report template to reproduce.

[adambutler]

I found the issue was that my index names were symbols instead of strings:

- searchkick index_name: :community_members
+ searchkick index_name: "community_members"