ActiveAdmin get value from form text field - ruby-on-rails

Question

I'm new in Ruby and make some simple admin using ActiveAdmin.
I have a model Question which I want to create, fill and store to database, it has an attribute themes (array of Theme models). When user creates a new record he doesn't enter themes manually but provide some string and system will automatically parse it and find or create themes. So I have code like that:
form do |f|
f.inputs "Questions Details" do
f.input :question, as: :string
f.input :autocomplete_themes, hint: "You should enter here multiple themes,
divide them with `,` or `;`"
end
f.actions
end
It creates a new field autocomplete_themes for entering string and it doesnt' exist in model Question. So what I want - is to get autocomplete_themes value like string and then use split() and my custom logic - but it gives an error.
before_create do |question|
array = []
puts "******"
puts :autocomplete_themes.text
themeTitles = :autocomplete_themes.split(",") #split(/,|;/)
for title in themeTitles do
theme = Theme.find_by(title: title)
theme = Theme.create(title: title) unless theme
array << theme
end
question.themes = array
end
Question: how can I get autocomplete_themes value as string? Thx!
Update: as I understood here - it looks like the similiar case, but there was problem with setting default value to custom field, but I need to get its value from code.

Answer 1

You did not specify the error you were getting, but based on the information you gave, you don't need autocomplete_themes to be a real database-backed attribute of the Question model, but rather you only need the information temporarily so that your before_create filter can use it to execute the appropriate logic.
Therefore, you could make autocomplete_themes a "virtual attribute" that is like a traditional member variable of an instance of Question.
class Question < ActiveRecord::Base
attr_writter :autocomplete_themes
attr_reader :autocomplete_themes
...other code
end
This will allow you to do things like:
#question.autocomplete_themes = "1,2,3"
themes_text = #question.auto_complete_themes
And best of all, ActiveAdmin supports having form inputs assign to virtual attributes. So you can keep your form like this:
form do |f|
f.inputs "Questions Details" do
f.input :question, as: :string
f.input :autocomplete_themes, hint: "You should enter here multiple themes,
divide them with `,` or `;`"
end
f.actions
end
And your before_filter would look like this:
before_create do |question|
array = []
themeTitles = question.autocomplete_themes.split(",") #split(/,|;/)
for title in themeTitles do
theme = Theme.find_by(title: title)
theme = Theme.create(title: title) unless theme
array << theme
end
question.themes = array
end