rails can this model code be refactored?

I would like to combine the finders better.

if params[:sort]
  if params[:sort] == 'industry_id'
    if params[:industry_id]
      @companies = Company.find_all_by_industry_id(params[:industry_id], :joins => "left join industries ind on industry_id = ind.id", :order => "ind.name" + " " + sort_direction)
    else
      @companies = Company.all(:joins => "left join industries ind on industry_id = ind.id", :order => "ind.name" +  " " + sort_direction)
    end
  else
    if params[:industry_id]
开发者_运维问答      @companies = Company.find_all_by_industry_id(params[:industry_id], :order => sort_column + " " + sort_direction)
    else
      @companies = Company.all(:order => sort_column + " " + sort_direction)
    end
  end
else
  if params[:industry_id]
    @companies = Company.find_all_by_industry_id(:joins => "left join industries ind on industry_id = ind.id", :order => "ind.name" + " " + sort_direction)
  else
    @companies = Company.all
  end
end

Assuming you have following model:

class Company
  belongs_to :industry

  def self.search p
    opt = {:conditions => {}}
    opt[:order] = (p[:sort] == "industry_id") ? "industries.name" : p[:sort]
    opt[:order]+= " " + (p[:sort_direction] || "ASC") if opt[:order].present?
    opt[:conditions][:industry_id] = p[:industry_id] if p[:industry_id].present? 
    if (p[:sort] == 'industry_id') or p[:industry_id].present?
      opt[:include] = :industry
    end
    all(opt)
  end
end

class Industry
  has_many :companies
end

Now you can use the search method in your controller:

Company.search(params)

Am I missing something or does it all boil down to this?

sort_joins = { 'ind.name' => 'left join industries ind on industry_id = ind.id' }
if params[:sort] == 'industry_id' || !params[:sort]
  sort_column = 'ind.name'
end

sort_column = nil if sort_column && !params[:industry_id]

options = { }
if sort_column
  options[:sort]  = "#{sort_column} #{sort_direction}"
  options[:joins] = sort_joins[sort_column] if sort_joins[sort_column]
end
if params[:industry_id]
  @companies = Company.find_all_by_industry_id(params[:industry_id], options)
else
  @companies = Company.all(options)
end