Question

i’m new to MongoDB and unsure how to use the Array-Field-Type.

So i created in my model

field :admins, type: Array

in this field i wanna store all user_ids that are “admins” of the model. But when I try to set this field, it doesnt save the Information in the Array it just simple creates an String with the ID. And due to my constrain that only Admins can edit my filter function

def check_if_admin
  unless Agency.find(params[:id]).admins.include?(current_agent.id)
    flash[:notice] = "Only possible as Admin."
    redirect_to root_path
  end
end

gets the error that

"can't convert Moped::BSON::ObjectId into String"

So I tried to initiate my field with in the create def as an array with ID:

@agency.admins = [current_agent.id]

That does the Trick for one user in the Array but how do I add IDs to this field?

When I go into my Edit Form:

<%= form_for(@agency) do |f| %>
  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :admins %><br />
    <%= f.text_field :admins %>  <br />
  </div>          
  <div class="field">
    <%= f.label :agents %><br />
    <%= f.text_field :agents %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

And Type in another User_ID by hand, I’m back to my error again.
Anyone knows how to get around that?

Thanks a ton for ur help!

Answer 1

This message means that at some point you stored a string where there should be an ObjectId. Ruby is trying to compare current_agent.id (an ObjectId) with params[:id] (a string).

It seems like you are not converting the input from the text_field in the form to an ObjectID before you push it onto the array.

Take the input from the admins field and make ObjectId’s like this:

BSON::ObjectId.new(string_representing_admin_id)

I’m guessing the admins field is a comma separated array of admin _ids and that you are using some _id values that are easy to work with, like a username instead of a generated ObjectId as this would be very burdensome to work with.

In that case you would probably split and strip the input and then make an array of the ObjectIds using a map/select.

It would be much easier to use a select field that displayed usernames for something like this in rails right?

Anyway, show some sample documents from the collection if you need more help.