使用中间人构建主题时出错（无法将nil转换为String），在/ load / local / bin / middleman：23：load中

Question

我尝试用ruby（css，js等）构建主题，但我遇到一个错误，我花了数小时试图解决它并阅读文档，但没有成功。

这是我执行：bundle exec middleman build --verbose时遇到的错误

== Request: /pages/forms/forms.html
       error  build/pages/forms/forms.html
can't convert nil into String
/var/lib/gems/1.9.1/gems/activesupport-3.2.14/lib/active_support/core_ext/string/output_safety.rb:114:in `concat'
/var/lib/gems/1.9.1/gems/activesupport-3.2.14/lib/active_support/core_ext/string/output_safety.rb:114:in `safe_concat'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-more/core_extensions/default_helpers.rb:63:in `block in content_tag'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-more/core_extensions/default_helpers.rb:63:in `each'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-more/core_extensions/default_helpers.rb:63:in `content_tag'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/vendored-middleman-deps/padrino-helpers-0.11.2/lib/padrino-helpers/tag_helpers.rb:140:in `safe_content_tag'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/vendored-middleman-deps/padrino-helpers-0.11.2/lib/padrino-helpers/form_helpers.rb:646:in `select_tag'
/home/polylan/Documents/dev/core-admin-release/source/pages/forms/forms.html.erb:60:in `block in singletonclass'
/home/polylan/Documents/dev/core-admin-release/source/pages/forms/forms.html.erb:65530:in `instance_eval'
/home/polylan/Documents/dev/core-admin-release/source/pages/forms/forms.html.erb:65530:in `singletonclass'
/home/polylan/Documents/dev/core-admin-release/source/pages/forms/forms.html.erb:65528:in `__tilt_16623600'
/var/lib/gems/1.9.1/gems/tilt-1.3.7/lib/tilt/template.rb:144:in `call'
/var/lib/gems/1.9.1/gems/tilt-1.3.7/lib/tilt/template.rb:144:in `evaluate'
/var/lib/gems/1.9.1/gems/tilt-1.3.7/lib/tilt/template.rb:77:in `render'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/rendering.rb:273:in `render_individual_file'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/rendering.rb:150:in `render_template'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/sitemap/resource.rb:150:in `block in render'
/var/lib/gems/1.9.1/gems/activesupport-3.2.14/lib/active_support/notifications.rb:125:in `instrument'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/util.rb:60:in `instrument'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/application.rb:196:in `instrument'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/sitemap/resource.rb:16:in `instrument'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/sitemap/resource.rb:121:in `render'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/request.rb:252:in `process_request'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/request.rb:202:in `block in call!'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/request.rb:201:in `catch'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/request.rb:201:in `call!'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/core_extensions/request.rb:187:in `call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/builder.rb:138:in `call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/urlmap.rb:65:in `block in call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/urlmap.rb:50:in `each'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/urlmap.rb:50:in `call'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-more/extensions/minify_css.rb:48:in `call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/lint.rb:49:in `_call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/lint.rb:37:in `call'
/var/lib/gems/1.9.1/gems/rack-1.5.2/lib/rack/builder.rb:138:in `call'
/var/lib/gems/1.9.1/gems/rack-test-0.6.2/lib/rack/mock_session.rb:30:in `request'
/var/lib/gems/1.9.1/gems/rack-test-0.6.2/lib/rack/test.rb:230:in `process_request'
/var/lib/gems/1.9.1/gems/rack-test-0.6.2/lib/rack/test.rb:57:in `get'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:138:in `render_to_file'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:280:in `block in execute!'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:277:in `each'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:277:in `execute!'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:199:in `invoke!'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/actions.rb:95:in `action'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli/build.rb:64:in `build'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/command.rb:27:in `run'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/invocation.rb:120:in `invoke_command'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor.rb:363:in `dispatch'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/base.rb:439:in `start'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli.rb:77:in `method_missing'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/command.rb:29:in `run'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/command.rb:128:in `run'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/invocation.rb:120:in `invoke_command'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor.rb:363:in `dispatch'
/var/lib/gems/1.9.1/gems/thor-0.18.1/lib/thor/base.rb:439:in `start'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/lib/middleman-core/cli.rb:22:in `start'
/var/lib/gems/1.9.1/gems/middleman-core-3.1.4/bin/middleman:18:in `<top (required)>'
/usr/local/bin/middleman:23:in `load'
/usr/local/bin/middleman:23:in `<main>'

这是结果：捆绑安装

Using i18n (0.6.5) 
Using multi_json (1.7.9) 
Using activesupport (3.2.14) 
Using chunky_png (1.2.8) 
Using coffee-script-source (1.6.3) 
Using execjs (1.4.0) 
Using coffee-script (2.2.0) 
Using fssm (0.2.10) 
Using sass (3.2.10) 
Using compass (0.12.2) 
Using ffi (1.9.0) 
Using tilt (1.3.7) 
Using haml (4.0.3) 
Using hike (1.2.3) 
Using json (1.7.7) 
Using kramdown (1.1.0) 
Using rb-fsevent (0.9.3) 
Using rb-inotify (0.9.1) 
Using rb-kqueue (0.2.0) 
Using listen (1.2.3) 
Using bundler (1.3.5) 
Using rack (1.5.2) 
Using rack-test (0.6.2) 
Using thor (0.18.1) 
Using middleman-core (3.1.4) 
Using middleman-more (3.1.4) 
Using sprockets (2.10.0) 
Using sprockets-helpers (1.0.1) 
Using sprockets-sass (1.0.1) 
Using middleman-sprockets (3.1.4) 
Using uglifier (2.1.2) 
Using middleman (3.1.4) 
Your bundle is complete!
Use `bundle show [gemname]` to see where a bundled gem is installed.

我的宝石文件

source 'http://rubygems.org'

gem "middleman", "~>3.1.4"
# Live-reloading plugin
gem "middleman-livereload", "~> 3.1.0"
gem 'json', '~> 1.7.7'

gem 'therubyracer'

if RUBY_PLATFORM =~ /linux/i
  gem 'rb-inotify', '~> 0.9'
else
  gem 'rb-inotify'
end

我用：ruby 1.9.1 ruby​​1.9.1-dev middleman（最新版本）nodejs therubyracer execjs

更新1：

多亏了j03w评论，该错误看来确实确实是forms.html.erb中这部分代码

<li>
  <label>Dropdown with search:</label>
  <%= select_tag :colors, options: @colorList.shuffle, class: "chzn-select" %>
</li>

<li>
  <label>Dropdown menu:</label>
  <%= select_tag :colors, options: @colorList.shuffle, class: "uniform" %>
</li>

这是我的config.rb的一部分，其中的数组是：

@release = false

@colorList = ["Aero blue","Air Force blue (RAF)","Air Force blue (USAF)","Air superiority blue","Alabama Crimson","Alice blue","Alizarin crimson","Alloy orange","Almond","Amaranth","Amazon","Amber",
              "SAE/ECE Amber (color)","American rose","Amethyst","Android Green","Anti-flash white","Antique brass","Antique bronze","Antique fuchsia "]

如果您需要更多信息，请随时询问。

如果您遇到相同的问题或对该错误有任何想法，将非常感谢您的帮助。

提前致谢。

亚恩

Answer 1

J03w是正确的。 似乎与传递给select_tag中的选项的@变量有关。

我无法弄清楚，但是想出了一个替代方法，该方法可以很好地使用ruby每个循环来创建选择列表选项。

<ul>
    <li>
        <label>Dropdown with search:</label>
        <select name="color-search" id="color-search" class="chzn-select">
            <% @colorList.shuffle.each do |color| %>
                <option value="<%= color %>"><%= color %></option>
            <% end %>
        </select>
    </li>

    <li>
        <label>Dropdown menu:</label>
        <select name="colors" id="colors" class="uniform">
            <% @colorList.shuffle.each do |color| %>
                <option value="<%= color %>"><%= color %></option>
            <% end %>
        </select>
    </li>
</ul>

我将继续研究是否可以解决您的最初问题，但希望这可以帮助您同时进行其他工作。

更新1：看起来中间人不喜欢将数组传递给select_tag的options参数，这很奇怪，因为它应该可以正常工作。 最初我以为是数组中的数据存储在@colorList中，但它们全部都签出了。

我什至尝试将其简化为Middleman文档中使用的示例，但仍然出现nil String错误。 我很沮丧

也许最新版本的Middleman有问题（我正在使用3.1.4）？