gem install json
Building native extensions. This could take a while...
ERROR: Error installing json:
ERROR: Failed to build gem native extension.
/home/user/.rvm/rubies/ruby-2.2.3/bin/ruby -r ./siteconf20150916-3216-1xudd6p.rb extconf.rb
creating Makefile
make "DESTDIR=" clean
make "DESTDIR="
compiling generator.c
linking shared-object json/ext/generator.so
/usr/bin/ld: cannot find -lgmp
collect2: error: ld returned 1 exit status
make: *** [generator.so] Error 1
make failed, exit code 2
Gem files will remain installed in /home/user/.rvm/gems/ruby-2.2.3/gems/json-1.8.3 for inspection.
Results logged to /home/user/.rvm/gems/ruby-2.2.3/extensions/x86_64-linux/2.2.0/json-1.8.3/gem_make.out
嘿.我正试图推进到heroku但是用这个结束了.首先,有sqlit3问题.现在,当我输入bundle时,我无法安装json.我现在应该怎么做？
提前致谢.
<div class="dropdown">
...
<%= ff.collection_select :vendor_id, @vendors, :id, :vendor, :include_blank => true, class: "dropdown-menu" %>
...
</div>
我有一个表单，然后我使用如上所示的 fields_for 来收集输入。但我无法看到程式化引导下拉如图所示这里。我应该做哪些更改才能看到 bootstrap 风格化的下拉菜单？