问题
I have a Rails 4 sample project (Blog) and I have created a simple middleware called 'request_timer' in config/initializers/request_timer.rb
#config/initializers/request_timer.rb
class RequestTimer
def initialize(app)
@app = app
end
def call(env)
start_time = Time.now
status, headers, response = @app.call(env)
stop_time = Time.now
[status, headers, response.body]
end
end
and I have added my middleware in config/application.rb in two ways
1 ) Adding as a constant
#config/application.rb
module Blog
class Application < Rails::Application
config.middleware.use RequestTimer
end
end
this way when I try to run my rails app I'm getting the error
/Users/sameera/workspace/ruby-rack/blog/config/application.rb:9:in `require': cannot load such file -- request_timer (LoadError)
from /Users/sameera/workspace/ruby-rack/blog/config/application.rb:9:in `<top (required)>'
from /Users/sameera/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.2/lib/rails/commands.rb:74:in `require'
from /Users/sameera/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.2/lib/rails/commands.rb:74:in `block in <top (required)>'
from /Users/sameera/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.2/lib/rails/commands.rb:71:in `tap'
from /Users/sameera/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.2/lib/rails/commands.rb:71:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'
2 ) Then I added my middleware as a string
#config/application.rb
module Blog
class Application < Rails::Application
config.middleware.use "RequestTimer"
end
end
This ways, it allows me to run the rails server, but when I access localhost:3000, it errors saying
NoMethodError (undefined method `each' for #<String:0x007fdf649b0028>):
rack (1.5.2) lib/rack/etag.rb:58:in `digest_body'
rack (1.5.2) lib/rack/etag.rb:26:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/flash.rb:241:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/cookies.rb:486:in `call'
activerecord (4.0.2) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.0.2) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call'
activerecord (4.0.2) lib/active_record/migration.rb:369:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.0.2) lib/active_support/callbacks.rb:373:in `_run__2755475928771109453__call__callbacks'
activesupport (4.0.2) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.2) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/reloader.rb:64:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.0.2) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `block in tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:25:in `tagged'
activesupport (4.0.2) lib/active_support/tagged_logging.rb:67:in `tagged'
railties (4.0.2) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.0.2) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.0.2) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.0.2) lib/rails/engine.rb:511:in `call'
railties (4.0.2) lib/rails/application.rb:97:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
/Users/sameera/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:138:in `service'
/Users/sameera/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/httpserver.rb:94:in `run'
/Users/sameera/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/webrick/server.rb:295:in `block in start_thread'
What would be the reason? I'm using Rails 4.0.2 and rack-1.5.2 and ruby 2.0.0p247.
回答1:
- Move
config/initializers/request_timer.rbtolib/request_timer.rbfolder. - Add
require_relative '../lib/request_timer'line toapplication.rbfile. - Change
config.middleware.use "RequestTimer"toconfig.middleware.use RequestTimer. Don't use quotes.
I remember that we can't use classes which are at initializers folder without require them at application.rb .
Regards.
回答2:
And much easier way to solve this is to put your request_timer.rb into
app/middleware/request_timer.rb and then added the middleware as a string in your config/application.rb
回答3:
You should place your middleware class inside the app/middleware folder. The added middleware should be injected in the list of middlewares which are by default added by rails.
Note: You can insert your middleware from anywhere in the code, but its preferred to insert a middleware in any of the initializers which you are adding for your app.
For example, to insert your middleware after rails inbuilt middleware params parser:
Rails.application.middleware.insert_after ActionDispatch::ParamsParser, "RequestTimer"
Additionally, you can also pass required parameters to your middleware something like:
options = { :foo => 'bar' }
Rails.application.middleware.insert_after ActionDispatch::ParamsParser, "SecuredClient", options
Then you can access these parameters in your middleware as follows:
class RequestTimer
def initialize(app, params)
@app = app
@params = params
end
end
回答4:
NoMethodError (undefined method 'each' for #<String:0x007fdf649b0028>),you should ensure reponse.body responds to 'each' method, but its class is String.You can fix the code like this: [status, headers, [response.body]]
Ruby 1.9 no longer has each on the String class.
Rack
To use Rack, provide an "app": an object that responds to the call method, taking the environment hash as a parameter, and returning an Array with three elements:
* The HTTP response code
* A Hash of headers
* The response body, which must respond toeach
来源：https://stackoverflow.com/questions/21293953/adding-a-custom-middleware-to-rails-4