Rails 4 - How to populate an array through a form

Question

I have three tables: illness, symptom and a secondary table to link the other two on a has_many through: relationship.

I wish to implement a system where users type in their symptoms and receive a list of possible illnesses.

Using the code below I can use find(1,2), for example, to show all illnesses that have symptoms 1 and 2 simultaneously. However, I want these two constants to be user-supplied data fed through a form. I'm somewhat new to RoR so I don't know how to do this.

symptoms = Symptom.find(params[:symptom_ids]) # symptom_ids is an array of ids

illnesses = Illness.joins(illness_symptoms: :symptom)
                    .where("symptoms.id in (?)", symptoms)
                    .group("illnesses.id")
                    .having("count(illnesses.id) >= ?", symptoms.length)

In the model:

 scope :with_symptoms, -> (symptoms) { joins(illness_symptoms: :symptom)
                                            .where("symptoms.id in (?)", symptoms)
                                            .group("illnesses.id")
                                            .having("count(illnesses.id) >= ?", symptoms.length) }

I use these with Illness.with_symptoms(Symptom.find(1,2)) (I'm looking for a way to replace 1,2 with user-supplied data).

I'm confused - if params[:symtom_ids] is the array of symptom ids the user has picked, doesn't your code already do what you want? — Frederick Cheung
– Frederick Cheung, Commented Nov 12, 2015 at 22:16
That's the thing, and I imagine it's quite a basic thing that I just didn't learn, I haven't been able to populate that array through a form. — Tsugihagi
– Tsugihagi, Commented Nov 12, 2015 at 22:28

chumakoff · Accepted Answer · 2015-11-13 08:18:44Z

2

You can do something like this in a form:

<% form_tag some_path do %>
    <% @symptoms.each do |symptom| %>
        <%= label_tag do %>
          <%= check_box_tag "symptom_ids[]", symptom.id %>
          <%= symptom.name %>
        <% end %>
    <% end %>
<% end %>

User will be able to use checkboxes to choose symptoms.

edited Nov 13, 2015 at 8:18

answered Nov 12, 2015 at 22:17

chumakoff

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2 Comments

Tsugihagi Over a year ago

Exactly what I needed, thank you so much. One question though: In the view, the check boxes look slightly above the names, as per nature of the code. Any way to fix this?

chumakoff Over a year ago

One common solution is to put the checkbox and the text into a label. It shows inline, looks good and what's very important it allows to check by clicking either on the checkbox or on the text. I edited my answer to show what I mean.

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