mostly remove the ParamsParser middleware

This can still be added to the middleware stack, but is really not
necessary.  I'll follow up with a commit that deprecates the constant

actionpack/test/abstract_unit.rb

@@ -104,7 +104,6 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
       middleware.use ActionDispatch::ShowExceptions, ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
       middleware.use ActionDispatch::DebugExceptions
       middleware.use ActionDispatch::Callbacks
-      middleware.use ActionDispatch::ParamsParser
       middleware.use ActionDispatch::Cookies
       middleware.use ActionDispatch::Flash
       middleware.use Rack::Head

actionview/test/abstract_unit.rb

@@ -151,7 +151,6 @@ class ActionDispatch::IntegrationTest < ActiveSupport::TestCase
       middleware.use ActionDispatch::ShowExceptions, ActionDispatch::PublicExceptions.new("#{FIXTURE_LOAD_PATH}/public")
       middleware.use ActionDispatch::DebugExceptions
       middleware.use ActionDispatch::Callbacks
-      middleware.use ActionDispatch::ParamsParser
       middleware.use ActionDispatch::Cookies
       middleware.use ActionDispatch::Flash
       middleware.use Rack::Head

guides/source/api_app.md

@@ -194,7 +194,6 @@ An API application comes with the following middlewares by default:
 - `ActionDispatch::RemoteIp`
 - `ActionDispatch::Reloader`
 - `ActionDispatch::Callbacks`
-- `ActionDispatch::ParamsParser`
 - `Rack::Head`
 - `Rack::ConditionalGet`
 - `Rack::ETag`
@@ -292,9 +291,9 @@ instructions in the `Rack::Sendfile` documentation.
 NOTE: The `Rack::Sendfile` middleware is always outside of the `Rack::Lock`
 mutex, even in single-threaded applications.
 
-### Using ActionDispatch::ParamsParser
+### Using ActionDispatch::Request
 
-`ActionDispatch::ParamsParser` will take parameters from the client in the JSON
+`ActionDispatch::Request#params` will take parameters from the client in the JSON
 format and make them available in your controller inside `params`.
 
 To use this, your client will need to make a request with JSON-encoded parameters
@@ -313,7 +312,7 @@ jQuery.ajax({
 });
 ```
 
-`ActionDispatch::ParamsParser` will see the `Content-Type` and your parameters
+`ActionDispatch::Request` will see the `Content-Type` and your parameters
 will be:
 
 ```ruby

guides/source/command_line.md

@@ -412,7 +412,7 @@ Ruby version              2.2.2 (x86_64-linux)
 RubyGems version          2.4.6
 Rack version              1.6
 JavaScript Runtime        Node.js (V8)
-Middleware                Rack::Sendfile, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, Rack::Head, Rack::ConditionalGet, Rack::ETag
+Middleware                Rack::Sendfile, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag
 Application root          /home/foobar/commandsapp
 Environment               development
 Database adapter          sqlite3

guides/source/configuring.md

@@ -214,7 +214,6 @@ Every Rails application comes with a standard set of middleware which it uses in
 * `ActionDispatch::Cookies` sets cookies for the request.
 * `ActionDispatch::Session::CookieStore` is responsible for storing the session in cookies. An alternate middleware can be used for this by changing the `config.action_controller.session_store` to an alternate value. Additionally, options passed to this can be configured by using `config.action_controller.session_options`.
 * `ActionDispatch::Flash` sets up the `flash` keys. Only available if `config.action_controller.session_store` is set to a value.
-* `ActionDispatch::ParamsParser` parses out parameters from the request into `params`.
 * `Rack::MethodOverride` allows the method to be overridden if `params[:_method]` is set. This is the middleware which supports the PATCH, PUT, and DELETE HTTP method types.
 * `Rack::Head` converts HEAD requests to GET requests and serves them as so.
 

guides/source/rails_on_rack.md

@@ -121,7 +121,6 @@ use ActiveRecord::QueryCache
 use ActionDispatch::Cookies
 use ActionDispatch::Session::CookieStore
 use ActionDispatch::Flash
-use ActionDispatch::ParamsParser
 use Rack::Head
 use Rack::ConditionalGet
 use Rack::ETag
@@ -284,10 +283,6 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 * Sets up the flash keys. Only available if `config.action_controller.session_store` is set to a value.
 
-**`ActionDispatch::ParamsParser`**
-
-* Parses out parameters from the request into `params`.
-
 **`Rack::Head`**
 
 * Converts HEAD requests to `GET` requests and serves them as so.

railties/lib/rails/application/default_middleware_stack.rb

@@ -72,7 +72,6 @@ module Rails
             middleware.use ::ActionDispatch::Flash
           end
 
-          middleware.use ::ActionDispatch::ParamsParser
           middleware.use ::Rack::Head
           middleware.use ::Rack::ConditionalGet
           middleware.use ::Rack::ETag, "no-cache"

railties/test/application/middleware_test.rb

@@ -43,7 +43,6 @@ module ApplicationTests
         "ActionDispatch::Cookies",
         "ActionDispatch::Session::CookieStore",
         "ActionDispatch::Flash",
-        "ActionDispatch::ParamsParser",
         "Rack::Head",
         "Rack::ConditionalGet",
         "Rack::ETag"
@@ -70,7 +69,6 @@ module ApplicationTests
         "ActionDispatch::Callbacks",
         "ActiveRecord::ConnectionAdapters::ConnectionManagement",
         "ActiveRecord::QueryCache",
-        "ActionDispatch::ParamsParser",
         "Rack::Head",
         "Rack::ConditionalGet",
         "Rack::ETag"