Convertir une requête SQL en Rails

Question

En ce moment, je fais mes requêtes complexes à la main pour ainsi dire. Mais je continue à rencontrer des problèmes. Par exemple.

  query = "SELECT histories.candidate_id 
      FROM histories 
      WHERE histories.institution_id IN (?) 
      GROUP BY histories.candidate_id 
      HAVING COUNT(*)= ?" 
      cand = [Code.find_by_sql([query, 

params['searches'][key], params['searches'][key].size])]

class History < ActiveRecord::Base 
    belongs_to :candidate 
end 
    create_table "histories", :force => true do |t| 
    t.string "job_title" 
    t.date  "start_date" 
    t.date  "finish_date" 
    t.string "basic_salary" 
    t.string "bonus" 
    t.integer "institution_id" 
    t.integer "candidate_id" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 
class Candidate < ActiveRecord::Base 
    # has_and_belongs_to_many :codes 
    has_many :codes, :through => :CandidatesCodes 
    has_many :histories 
    has_many :contacts 
    has_many :compensations 
end 

Ceci retourne une liste des ids candidats .. mais veux je veux que ce retour est une liste de candidats comment pourrais-je faire les rails ainsi?

C'est la suggestion de Brians, et je l'ai essayé mais je reçois non initialisée Histoire constante des candidats

 cand = History.find(:all, 
     :joins => :candidates, 
     :select => "candidates.*", 
     :conditions => [ "institution_id IN (?)", params['searches'][key] ], 
     :group => [ "candidate_id HAVING count(*) = ?", params['searches'][key].size ] 
    ) 

Answer 1

Essayez ceci:

Candidate.all(
    :joins => :histories, 
    :conditions => {:histories=> {:institution_id => params[:searches][key]}}, 
    :group => "candidates.id", 
    :having => "count(candidates.id) >= %i" % params[:searches][key].size 
) 

Cela devrait générer le code SQL suivant:

SELECT candidates.* 
FROM  candidates AS candidates 
JOIN  histories AS histories ON histories.candidate_id = candidates.id 
WHERE histories.institution_id IN (1,2,3) 
GROUP BY candidates.id 
HAVING COUNT(candidates.id) >= 3 

Answer 2

Essayez ceci.

En supposant que vous avez le mode d'histoire

History.find(:all , 
    :conditions=>[" institution_id IN (?) ",params['searches'][key] ], 
    :group => ["candidate_id HAVING count(*) = ? " ,params['searches'][key].size ] 
) 

Answer 3

pour cette solution (bâtiment sur l'approche de Dinesh ci-dessus.

candidates = History.find(:all, 
    :joins => :candidates, 
    :select => "candidates.*" 
    :conditions => ["institution_id IN (?)", params['searches'][key]], 
    :group => ["candidate_id HAVING count(*) = ?", params['searches'][key].size] 
) 

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