Ruby on Rails - 未定义的方法`split'代表nil：StocksController中的NilClass / NoMethodError #search

Posted 2021-04-15

我是Rails的新手，我正在Udemy上完成Ruby on Rails开发人员课程。当我尝试去/search_stocks路线时，我收到以下错误。

这是当前状态下的回购（我也有下面粘贴的代码）：https://github.com/sarahbasinger/rails-stock-tracker

这是Udemy课程回购：https://github.com/udemyrailscourse/finance-tracker

该课程的TA表明它可能是一个宝石版本冲突。我正在使用Rails 5.1.4（也许是一个新手的错误 - 我认为使用最新和最好的将是一个很好的方式去）。课程中的老师正在使用Rails 4. TA建议我使用与课程相同的宝石版本，所以我更新了我的Gemfile以匹配Gemfile课程，运行bundle install，然后我甚至无法获得rails服务器运行。我得到了一个不同的错误。所以我回过头来尝试使用Rails 5运行这个应用程序。但是，我没有尝试解决gem版本冲突的经验，如果这是问题。

这是相关的代码：

模型

class Stock < ActiveRecord::Base

    def self.new_from_lookup(ticker_symbol)
        looked_up_stock = StockQuote::Stock.quote(ticker_symbol)
        new(name: looked_up_stock.name, ticker: looked_up_stock.symbol, last_price: looked_up_stock.l)
    end
end

调节器

class StocksController < ApplicationController

    def search
        @stock = Stock.new_from_lookup(params[:stock])
        render json: @stock
    end
end

视图

<h1>My portfolio</h1>
<h3>Search for stocks</h3>
<div id="stock-lookup">
<%= form_tag search_stocks_path, method: :get, id: "stock-lookup-form" do %>
        <div class="form-group row no-padding text-center col-md-12">
            <div class="col-md-10">
                <%= text_field_tag :stock, params[:stock], placeholder: "Stock ticker symbol", autofocus: true, class: "form-control search-box input-lg" %>
            </div>
            <div class="col-md-2">
                <%= button_tag(type: :submit, class: "btn btn-lg btn-success") do %>
                    <i class="fa fa-search"></i> Look up a stock
                <% end %>
            </div>
        </div>
    <% end %>
</div>

的Gemfile

source 'https://rubygems.org'

git_source(:github) do |repo_name|
  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
  "https://github.com/#{repo_name}.git"
end


# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 5.1.4'
gem 'devise'
gem 'twitter-bootstrap-rails'
gem 'jquery-rails'
gem 'devise-bootstrap-views'
gem 'stock_quote'
# Use Puma as the app server
gem 'puma', '~> 3.7'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for javascript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.5'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 3.0'
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

group :development, :test do
  gem 'sqlite3'
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '~> 2.13'
  gem 'selenium-webdriver'

end

group :development do
  # Access an IRB console on exception pages or by using <%= console %> anywhere in the code.
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '>= 3.0.5', '< 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'

end

group :production do
  gem 'pg'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

任何帮助表示赞赏！

答案

在我看来，你需要一个名为“stock”的参数。在第4行

@stock = Stock.new_from_lookup(params[:stock])

它正在寻找一个名为“stock”的URL参数，它是一个股票代码。尝试类似的东西：

localhost:3000/search_stocks?stock=goog

这将创建一个股票参数并给它一些东西来查找。您还可以输入一些代码来处理param为零的情况。

def search
    if params[:stock]
        @stock = Stock.new_from_lookup(params[:stock])
    else
        # you should have some directions here for what happens if there is no stock param given.
        @stock = nil
    end
    render json: @stock
end

现在我想到它，可能甚至更好地在模型中做到这一点：

def self.new_from_lookup(ticker_symbol)
    if ticker_symbol
        looked_up_stock = StockQuote::Stock.quote(ticker_symbol)
    else
        # something here for a missing stock param
        looked_up_stock = Stock.first
    end
    new(name: looked_up_stock.name, ticker: looked_up_stock.symbol, last_price: looked_up_stock.l)
end

我希望这有帮助！

另一答案

您可以尝试以下操作，因为大多数时候gem功能更新，这就是为什么不在实现此代码。我最近在下面测试了这种类型的项目编写代码。

模型

def self.find_by_ticker(ticker_symbol)
    where(ticker: ticker_symbol).first
end

def self.new_from_lookup(ticker_symbol)
    begin
        looked_up_stock = StockQuote::Stock.quote(ticker_symbol)
        price = strip_commas(looked_up_stock.l)
        new(name: looked_up_stock.name, ticker: looked_up_stock.symbol, last_price: price)
    rescue Exception => e
        return nil
    end
end

def self.strip_commas(number)
    number.gsub(",", "")
end

希望能有所帮助