Rails使用可选参数进行搜索？

Question

当搜索可以提供许多可选参数(如ID,Zip,City和State)时,如何在数据库上进行搜索？这些可以具有值或完全空白.我将如何进行类似的rails查询？

Answer 1

通常的建议是将逻辑移动到模型并使控制器尽可能精益.过滤方法有不同的方法,第一种方法:

class Record < ActiveRecord::Base
  def self.filter(attributes)
    attributes.select { |k, v| v.present? }.reduce(all) do |scope, (key, value)|
      case key.to_sym
      when :id, :zip # direct search
        scope.where(key => value)
      when :city, :state # regexp search
        scope.where(["#{key} ILIKE ?", "%#{value}%"])
      when :order # order=field-(ASC|DESC)
        attribute, order = value.split("-") 
        scope.order("#{self.table_name}.#{attribute} #{order}")
      else # unknown key (do nothing or raise error, as you prefer to)
        scope
      end 
    end  
  end
end

第二种方法,写一个filter只使用现有范围的裸:

class Record < ActiveRecord::Base
  SUPPORTED_FILTERS = [:id, :city, ...]
  scope :id, ->(value) { where(id: value) }
  scope :city, ->(value) { where(city: "%#{value}%") }
  ...

  def self.filter(attributes)
    attributes.slice(*SUPPORTED_FILTERS).reduce(all) do |scope, (key, value)|
      value.present? ? scope.send(key, value) : scope
    end  
  end
end

对于现在使用ActionController :: Parameters的Rails 5,filter方法的语法是:

def self.filter(attributes)
  attributes.permit(SUPPORTED_FILTERS).to_hash.reduce(all) do |scope, (key, value)|
    value.present? ? scope.send(key, value) : scope
  end  
end

可以从应用程序的任何位置调用模型,因此它们可重复使用且更易于测试.现在控制器看起来很简单:

class RecordsController < ApplicationController::Base
  respond_to :html, :xml

  def index
    @records = Record.filter(params)
  end
end

Answer 2

您可以构建查询:

conditions = {}
conditions[:city] = city unless city.blank?
conditions[:zip] = zip unless zip.blank?
conditions[:state] = state unless state.blank?
Address.find(:all, :conditions => conditions)