Working with Rails arrays in Postgres - ruby-on-rails

Question

I have a postgres column called content which is an array.
But when trying to use it in a form I'm getting:
can't cast ActionController::Parameters to text
Despite the fact that the output looks pretty good:
{"utf8"=>"✓",
"_method"=>"patch",
"authenticity_token"=>"NkK4BggxknfEn0A8shTs06xmesERaZdYtZdl9oEEUTk=",
"notification_template"=>{"content"=>{"0"=>"Join us {{event_time}} {{{twitter_name}}} to win Big! hint: {{{question}}} #quiz {{location_tags}} {{url}} sdfsdfsdf"}},
"commit"=>"Update Notification template",
"id"=>"25"}
strong params
params.require(:notification_template).permit(:name, :content => {})
routes
resources :notification_templates do
get 'edit/:id', to: 'notification_templates#edit_content', as: 'edit_content'
end
controller
def edit_content
#notification_template = NotificationTemplate.find(params[:notification_template_id])
end
def update
if #notification_template.update(notification_template_params)
redirect_to admin_notification_template_path(#notification_template), notice: 'Social message was successfully updated.'
else
render action: 'edit'
end
end
my form
the url looks like: /notification_templates/25/edit_content/7 # custom action, but uses normal update
<%= simple_form_for([:admin, #notification_template]) do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.simple_fields_for :content do |fields| %>
<%= fields.input params[:id], input_html: { value: #notification_template.content[params[:id].to_i] } %>
<% end %>
</div>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
the DB column
add_column :notification_templates, :content, :text, array: true, default: []
Lastly, I was unsure about the conventions for adding it. The above worked fine, but I also noticed other possibilities such as
add_column :notification_templates, :content, :text, array: true, default: []
add_column :notification_templates, :content, :sting, array: true, default: []
add_column :notification_templates, :content, :text, array: true, default: {}
I choose the first one on the basis that a string wouldn't allow for as many characters as I might eventually need and text is more convenient. Also the default of [] vs {} or '{}'
But in postgres is see content text[] DEFAULT '{}'::text[]
log
Started PATCH "/admin/notification_templates/25" for 127.0.0.1 at 2014-11-28 14:25:43 +0100
Processing by Admin::NotificationTemplatesController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"NkK4BggxknfEn0A8shTs06xmesERaZdYtZdl9oEEUTk=", "notification_template"=>{"content"=>{"4"=>"{{{question}}} Study up and stop by {{{twitter_name}}} {{event_time}} for a #quiz {{location_tags}} {{url}} sdfsdfsdf"}}, "commit"=>"Update Notification template", "id"=>"25"}
User Load (0.9ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 ORDER BY "users"."id" ASC LIMIT 1
NotificationTemplate Load (0.5ms) SELECT "notification_templates".* FROM "notification_templates" WHERE "notification_templates"."id" = $1 LIMIT 1 [["id", 25]]
(0.3ms) BEGIN
(0.3ms) ROLLBACK
Completed 500 Internal Server Error in 54ms
Reporting exception: can't cast ActionController::Parameters to text
TypeError (can't cast ActionController::Parameters to text):
app/controllers/admin/notification_templates_controller.rb:40:in `update'
Rendered /Users/holden/.rvm/gems/ruby-2.0.0-p481#questionone-2.0/gems/actionpack-4.1.7/lib/action_dispatch/middleware/templates/rescues/_source.erb (1.1ms)
Rendered /Users/holden/.rvm/gems/ruby-2.0.0-p481#questionone-2.0/gems/actionpack-4.1.7/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (2.0ms)
Rendered /Users/holden/.rvm/gems/ruby-2.0.0-p481#questionone-2.0/gems/actionpack-4.1.7/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.4ms)
Rendered /Users/holden/.rvm/gems/ruby-2.0.0-p481#questionone-2.0/gems/actionpack-4.1.7/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (27.5ms)
UPDATE
I also observed that update array type field doesn't work as expected in the console.
eg. if I attempt to update a member of the array, something = record.content[2] = 'blah' it appears to work. But when I save the record it doesn't update it.

Answer 1

Yeah, Rails postgres Arrays are still a bit wonky. Hstore is a bit easier.
You may be better served going thru a virtual attribute and doing what you want expressly rather than relying on standard rails behavior through a form.
eg.
def content_member=(member)
unless member.blank?
self.content_will_change!
self.content[member.keys.first.to_i] = member.values.first
end
end
You also need to let rails know if you're going to update a member of an array, that's why it doesn't work in the console.
There's a full explanation here:
Rails 4 Postgresql array data-type: updating values