带可选参数的 Rails 搜索? [英] Rails Search with optional parameters?
问题描述
当搜索可以提供许多可选参数(例如 ID、邮编、城市和州)时,我将如何对数据库进行搜索?这些可以有值或完全为空.我将如何进行这样的 rails 查询?
How would I do a search on a database when the search can provide many optional parameters such as ID, Zip, City, and State? These can either have values or be blank entirely. How would I make a rails query like that?
推荐答案
通常的建议是将逻辑移到模型中,并使控制器尽可能精简.过滤方法有多种方法,第一种:
The usual advice is to move logic to the model and keep the controller as lean as possible. There are different approaches for the filter method, the first one:
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,编写一个仅使用现有范围的裸filter
:
A second approach, write a bare filter
that only uses existing scopes:
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,过滤器方法的语法是:
For Rails 5, which now uses ActionController::Parameters, the syntax for the filter method is:
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
模型可以从您应用的任何位置调用,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:
Models can be called from anywhere in your app, so they are re-usable and easier to test. Now the controller looks as simple as:
class RecordsController < ApplicationController::Base
respond_to :html, :xml
def index
@records = Record.filter(params)
end
end
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