parameters & params
path_parameters
request.parameters
=> {"utf8"=>"✓",
"authenticity_token"=>"+.../hHj0C5Ao7CxXYwlejyghpNM3elUVw==",
"user"=>{"name"=>"kelby", "email"=>""},
"commit"=>"Create User",
"controller"=>"users",
"action"=>"create"}
# 另:
request.parameters == params
=> true
# 但它们两者并不是完全等价的
request.path_parameters
=> {:controller=>"users", :action=>"create"}