Query "where" with ruby on rails

Question

I've in my app, posts as ideas, and these ideas belongs to an activity and a status. And I want to sort them by activity for one status so I did in my controller

@idees_en_place = Idee.where(statut_id= "2")
@activites = Activite.all

And in my view :

<% @activites.each do |activite| %>
  <div class="idee en-place col-lg-5" style="background:#<%= activite.color%>">
    <h2><%= activite.name %></h2>
    <p>
     <% @idees_en_place.where(activite_id = activite.id).limit(3).each do |idee| %>
     <div class="idee">
       <h6><%= link_to idee.title, idee %></h6>
      </div>
     <% end %>
  </p>
  </div>
<% end %>

But that doesn't work, in each part of an activity the ideas are not sorted. I think it's a little mistake but I don't know how to resolve this

should be: @idees_en_place = Idee.where(statut_id: 2)

pangpang
– pangpang

2015-05-19 08:30:00 +00:00
Commented May 19, 2015 at 8:30 — pangpang
– pangpang, Commented May 19, 2015 at 8:30
Can you add how you mapped your models?

Francesco Pirrone
– Francesco Pirrone

2015-05-19 08:55:03 +00:00
Commented May 19, 2015 at 8:55 — Francesco Pirrone
– Francesco Pirrone, Commented May 19, 2015 at 8:55

Andrey Deineko · Accepted Answer · 2015-05-19 08:34:48Z

1

@idees_en_place = Idee.where(statut_id= "2")

There are two problems with this code.

First, id is a Integer type (unless you've defined it as String). Second, its a key value you pass to where clause, and you pass these either as

:status_id => 2 # old hashrocket syntax

or

status_id: 2 # new syntax

The same goes with this part

@idees_en_place.where(activite_id = activite.id)

it should be

@idees_en_place.where(activite_id: activite.id)

answered May 19, 2015 at 8:34

Andrey Deineko

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2 Comments

Simon M. Over a year ago

Thanks ! But now, no ideas are displayed

Andrey Deineko Over a year ago

@MilletoSimon this is a question to you and associations between models in your app, not to me :) Most likely there is no Ideas with status_id of 2. Please accept the answer if it taught you something about quering db

Emu · Accepted Answer · 2015-05-19 08:32:53Z

0

In Controller

@idees_en_place = Idee.where(statut_id: 2)
@activites = Activite.all

In View

<% @activites.each do |activite| %>
  <div class="idee en-place col-lg-5" style="background:#<%= activite.color%>">
    <h2><%= activite.name %></h2>
    <p>
     <% @idees_en_place.where(activite_id: activite.id).limit(3).each do |idee| %>
     <div class="idee">
       <h6><%= link_to idee.title, idee %></h6>
      </div>
     <% end %>
  </p>
  </div>
<% end %>

answered May 19, 2015 at 8:32

Emu

5,9253 gold badges36 silver badges53 bronze badges

1 Comment

Aleksei Matiushkin Over a year ago

One should never execute queries in views. On 100 activities there will be 100 queries against database executed.

Mohammad AbuShady · Accepted Answer · 2015-05-19 09:04:23Z

I just wanna point out that you will run into an N+1 queries issue, to avoid this you should preload every thing, instead of doing queries in the views.

The controller:

#change if the association name is different
@activites = Activite.includes(:idees)

The view

<% @activites.each do |activite| %>
  <div class="idee en-place col-lg-5" style="background:#<%= activite.color%>">
    <h2><%= activite.name %></h2>
    <p>
     <% activitie.idees[0..2].each do |idee| %>
     <div class="idee">
       <h6><%= link_to idee.title, idee %></h6>
      </div>
     <% end %>
  </p>
  </div>
<% end %>

Notes:

I've used the [0..2] format because I wanted to avoid ActiveRecord from doing a new query, another method would be limiting the query using something like this

@activites = Activite.includes(:idees).merge(Idee.limit(3))

Then you won't need to use any limitation in the views, but I haven't tested this, don't have access on a rails machine right now.

uma · Accepted Answer · 2015-05-19 10:00:11Z

I think that the following code will help you:

Since your Idee belong to activity and status that's why you have activity_id and status_id in your Idee table.

you may find out all the idee for a status by using:

Idee.where(:status_id => 2)

and you can sort Idee in Asc or desc order by using order

idees = Idee.join(:activity).where(:status_id => 2).order(:activity_id => :asc)
idees = Idee.join(:activity).where(:status_id => 2).order(:activity_id => :desc)

<% activity_id = -1%>
<@idees.each do |idee| %>
  <div class="idee en-place col-lg-5" style="background:#<%= idee.activite.color%>">
  <h2><%= idee.activity.name %></h2>
  <p>
    <% if activity_id != idee.activity_id  %>
      <% activity_id = idee.activity.id %>
      <% counter = 0 %>
    <% end %>
    <% if counter < 3 %>
      <% counter = counter + 1%>
      <div class="idee">
        <h6><%= link_to idee.title, idee %></h6>
      </div>
    <% end %>
  </p>
</div>

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