Allows to set a global ParamBuilder

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * Your contribution here.
+* [#1833](https://github.com/ruby-grape/grape/pull/1833): Allows to set the `ParamBuilder` globally - [@myxoh](https://github.com/myxoh).
 
 #### Fixes
 

README.md

@@ -22,13 +22,14 @@
   - [Rails](#rails)
   - [Modules](#modules)
 - [Remounting](#remounting)
-  - [Configuration](#configuration)
+  - [Mount Configuration](#mount-configuration)
 - [Versioning](#versioning)
   - [Path](#path)
   - [Header](#header)
   - [Accept-Version Header](#accept-version-header)
   - [Param](#param)
 - [Describing Methods](#describing-methods)
+- [Configuration](#configuration)
 - [Parameters](#parameters)
   - [Params Class](#params-class)
   - [Declared](#declared)
@@ -395,7 +396,7 @@ end
 
 Assuming that the post and comment endpoints are mounted in `/posts` and `/comments`, you should now be able to do `get /posts/votes`, `post /posts/votes`, `get /comments/votes`.
 
-### Configuration
+### Mount Configuration
 
 You can configure remountable endpoints for small details changing according to where they are mounted.
 
@@ -541,6 +542,29 @@ end
 
 [grape-swagger]: https://github.com/ruby-grape/grape-swagger
 
+## Configuration
+
+Use `Grape.configure` to set up global settings at load time.
+Currently the configurable settings are:
+
+* `param_builder`: Sets the [Parameter Builder](#parameters), defaults to `Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder`.
+
+To change a setting value make sure that at some point on load time the code the following code runs
+
+```ruby
+Grape.configure do |config|
+  config.setting = value
+end
+```
+
+For example, for the `param_builder`, the following code could run in an initializers:
+
+```ruby
+Grape.configure do |config|
+  config.param_builder = Grape::Extensions::Hashie::Mash::ParamBuilder
+end
+```
+
 ## Parameters
 
 Request parameters are available through the `params` hash object. This includes `GET`, `POST`
@@ -618,6 +642,8 @@ params do
 end
 ```
 
+Or globally with the [Configuration](#configuration) `Grape.configure.param_builder`.
+
 In the example above, `params["color"]` will return `nil` since `params` is a plain `Hash`.
 
 Available parameter builders are `Grape::Extensions::Hash::ParamBuilder`, `Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder` and `Grape::Extensions::Hashie::Mash::ParamBuilder`.

lib/grape.rb

@@ -34,7 +34,6 @@ module Grape
     autoload :Namespace
 
     autoload :Path
-
     autoload :Cookies
     autoload :Validations
     autoload :ErrorFormatter
@@ -194,6 +193,7 @@ module ServeFile
   end
 end
 
+require 'grape/config'
 require 'grape/util/content_types'
 
 require 'grape/validations/validators/base'

lib/grape/config.rb

@@ -0,0 +1,32 @@
+module Grape
+  module Config
+    class Configuration
+      ATTRIBUTES = %i[
+        param_builder
+      ].freeze
+
+      attr_accessor(*ATTRIBUTES)
+
+      def initialize
+        reset
+      end
+
+      def reset
+        self.param_builder = Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+      end
+    end
+
+    def self.extended(base)
+      def base.configure
+        block_given? ? yield(config) : config
+      end
+
+      def base.config
+        @configuration ||= Grape::Config::Configuration.new
+      end
+    end
+  end
+end
+
+Grape.extend Grape::Config
+Grape.config.reset

lib/grape/request.rb

@@ -5,7 +5,7 @@ class Request < Rack::Request
     alias rack_params params
 
     def initialize(env, options = {})
-      extend options[:build_params_with] || Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder
+      extend options[:build_params_with] || Grape.config.param_builder
       super(env)
     end
 

spec/grape/config_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe '.configure' do
+  before do
+    Grape.configure do |config|
+      config.param_builder = 42
+    end
+  end
+
+  after do
+    Grape.config.reset
+  end
+
+  it 'is configured to the new value' do
+    expect(Grape.config.param_builder).to eq 42
+  end
+end

spec/grape/request_spec.rb

@@ -62,6 +62,30 @@ module Grape
       end
     end
 
+    describe 'when the param_builder is set to Hashie' do
+      before do
+        Grape.configure do |config|
+          config.param_builder = Grape::Extensions::Hashie::Mash::ParamBuilder
+        end
+      end
+
+      after do
+        Grape.config.reset
+      end
+
+      subject(:request_params) { Grape::Request.new(env, opts).params }
+
+      context 'when the API does not include a specific param builder' do
+        let(:opts) { {} }
+        it { is_expected.to be_a(Hashie::Mash) }
+      end
+
+      context 'when the API includes a specific param builder' do
+        let(:opts) { { build_params_with: Grape::Extensions::Hash::ParamBuilder } }
+        it { is_expected.to be_a(Hash) }
+      end
+    end
+
     describe '#headers' do
       let(:options) do
         default_options.merge(request_headers)