Ruby on rails ActionDispatch:：升级到Rails 5后更换ParamSpaser

将应用程序从Rails 4.2.9迁移到5.2.1

这是最新一期:

$ rails console
/Users/meltemi/rails/myapp/config/initializers/disable_xml_params.rb:3:in `<top (required)>': uninitialized constant ActionDispatch::ParamsParser (NameError)
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:657:in `block in load_config_initializer'
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-5.2.1/lib/active_support/notifications.rb:170:in `instrument'
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:656:in `load_config_initializer'

说：

ActionDispatch:：ParamSpaser已弃用，并已从中间件堆栈中删除。要配置参数解析器，请使用ActionDispatch:：Request.parameter_parsers=。（承诺，承诺）

因此，我尝试了以下方法：

ActionDispatch::Request.parameter_parsers.delete(Mime::XML)

但这会导致更多的错误：

$ rails console
/Users/meltemi/rails/myapp/config/initializers/disable_xml_params.rb:3:in `<top (required)>': uninitialized constant Mime::XML (NameError)
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:657:in `block in load_config_initializer'
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-5.2.1/lib/active_support/notifications.rb:170:in `instrument'
    from /Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:656:in `load_config_initializer'

$rails控制台
/Users/meltemi/rails/myapp/config/initializers/disable_xml_params.rb:3:in`'：未初始化常量Mime:：xml（NameError）
来自/Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:657:“加载中的块配置\初始值设定项”
来自/Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-5.2.1/lib/active\u support/notifications.rb:170:在“仪器”中
来自/Users/meltemi/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/railties-5.2.1/lib/rails/engine.rb:656:“加载配置\初始值设定项”

---

是否有更好的方法调用该对象的.delete？

您必须从

参数解析器中获取现有值，根据需要对其进行修改，然后将值重置为修改后的值。从：

参数\u解析器=（解析器）

为给定MIME类型配置参数解析器

它接受一个散列，其中键是MIME类型的符号，值是proc

在您的特定情况下，您应该查看
original_parsers
中的解析器，以查看是否有任何内容需要删除。在我手边有一个简单的Rails 5应用程序上，我仅有的值是：

=> {
    :json => #<Proc:0x00007fe818fc6fb8@/Users/foo/.rvm/gems/ruby-2.6.0-preview2/gems/actionpack-5.2.1/lib/action_dispatch/http/parameters.rb:11 (lambda)>
}

您可以找到其他有用的信息

original_parsers = ActionDispatch::Request.parameter_parsers
xml_parser = -> (raw_post) { Hash.from_xml(raw_post) || {} }
new_parsers = original_parsers.merge(xml: xml_parser)
ActionDispatch::Request.parameter_parsers = new_parsers

=> {
    :json => #<Proc:0x00007fe818fc6fb8@/Users/foo/.rvm/gems/ruby-2.6.0-preview2/gems/actionpack-5.2.1/lib/action_dispatch/http/parameters.rb:11 (lambda)>
}

ActionDispatch::Request.parameter_parsers = ActionDispatch::Request.parameter_parsers.except(:json)