Configuring strong parameters for dynamic keys

I'm attempting to provide a form that allows an admin to edit all values of a particular model Submission, almost as though it was a spreadsheet. Submission is comprised of one string field :domain.

The problem is that I can't figure out how to deal with strong params within this context. I've found similar examples of dealing with dynamic keys like this one but I can't quite figure out how to apply them to my parameter structure. I think I'm just not clear enough on how tap works.

Here's an example of my parameters:

{"3"=>{"domain"=>"domain3"}, "2"=>{"domain"=>"domain2"}, "1"=>{"domain"=>"domain1"}

In case it helps, here's the form I'm using:

<%= form_tag update_multiple_submissions_path, method: :put do %>
    <table data-toggle="table" data-sort-name = "domain" data-sort-order = "desc">
        <thead>
            <th data-field="domain" data-sortable="true">Domain</th>
        </thead>
        <tbody>
            <% @submissions.each do |submission| %>
                <%= simple_fields_for "submissions[]", submission, defaults: {label: false} do |f| %>
                    <tr>
                        <td><%= submission.domain %><%= f.input :domain %></td>
                    </tr>
                <% end %>
            <% end %>
        </tbody>
    <table>
    <%= submit_tag "Save" %>
<% end %>

And in case you're curious, here's the update_multiple method from my controller. If this looks familiar, I got the outline from a railscast, which was very effective in rails3 before strong params was (were?) ubiquitous.

  def update_multiple
    logger.debug "update_multiple #{submission_params}"
    @submissions = Submission.update(submission_params[:submissions].keys, params[:submissions].values)

    flash[:notice] = "Updated Submissions"

    redirect_to review_submissions_path
  end

This works very well if I bypass strong prams altogether using params.permit! but, of course, this is an unacceptable solution.

Thanks for any help!

You can use a "virtual" model (a model without a table):

class SubmissionFormCollection
  include ActiveModel::Model

  attr_accessor :submissions
end

def edit_multiple
  @collection = SubmissionFormCollection.new(
    Submission.all
  )
end

<% simple_form_for(@collection, as: :some_param_key, path: update_multiple_submissions_path, method: :put) do |f| %>
  <%= f.fields_for(:submissions) do |s| %>
    <%= s.input :domain %></td>
  <% end %>
<% end %>

params.require(:some_param_key)
      .permit(submissions: [:domain])

Although I would probably use ajax and perform it as a series of atomical PATCH requests for each item edited instead as it will give direct user feedback and a better API.