From 2b7be0cd914d74bfc2e3296bf3614b9b0425d550 Mon Sep 17 00:00:00 2001
From: unleashy <unleashy@users.noreply.github.com>
Date: Wed, 2 Oct 2019 11:42:18 -0300
Subject: [PATCH] Add .configuration to Grape::API (fixes #1906) (#1907)

---
 CHANGELOG.md           |  1 +
 README.md              | 11 +++++++++++
 lib/grape/api.rb       | 15 +++++++++++++++
 spec/grape/api_spec.rb | 38 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 65 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52a86c4a80..936ca5ee91 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 * Your contribution here.
 * [#1904](https://github.com/ruby-grape/grape/pull/1904): Allows Grape to load files on startup rather than on the first call - [@myxoh](https://github.com/myxoh).
+* [#1907](https://github.com/ruby-grape/grape/pull/1907): Adds outside configuration to Grape with `configure` - [@unleashy](https://github.com/unleashy).
 
 #### Fixes
 
diff --git a/README.md b/README.md
index 96388ea59b..ebaf1ac834 100644
--- a/README.md
+++ b/README.md
@@ -631,6 +631,17 @@ Grape.configure do |config|
 end
 ```
 
+You can also configure a single API:
+
+```ruby
+API.configure do |config|
+  config[key] = value
+end
+```
+
+This will be available inside the API with `configuration`, as if it were
+[mount configuration](#mount-configuration).
+
 ## Parameters
 
 Request parameters are available through the `params` hash object. This includes `GET`, `POST`
diff --git a/lib/grape/api.rb b/lib/grape/api.rb
index 0387bac9c7..fa707d2e92 100644
--- a/lib/grape/api.rb
+++ b/lib/grape/api.rb
@@ -42,6 +42,21 @@ def override_all_methods!
         end
       end
 
+      # Configure an API from the outside. If a block is given, it'll pass a
+      # configuration hash to the block which you can use to configure your
+      # API. If no block is given, returns the configuration hash.
+      # The configuration set here is accessible from inside an API with
+      # `configuration` as normal.
+      def configure
+        config = @base_instance.configuration
+        if block_given?
+          yield config
+          self
+        else
+          config
+        end
+      end
+
       # This is the interface point between Rack and Grape; it accepts a request
       # from Rack and ultimately returns an array of three values: the status,
       # the headers, and the body. See [the rack specification]
diff --git a/spec/grape/api_spec.rb b/spec/grape/api_spec.rb
index 2dca918891..63c1623bb6 100644
--- a/spec/grape/api_spec.rb
+++ b/spec/grape/api_spec.rb
@@ -3754,6 +3754,44 @@ def before
     end
   end
 
+  describe '.configure' do
+    context 'when given a block' do
+      it 'returns self' do
+        expect(subject.configure {}).to be subject
+      end
+
+      it 'calls the block passing the config' do
+        call = [false, nil]
+        subject.configure do |config|
+          call = [true, config]
+        end
+
+        expect(call[0]).to be true
+        expect(call[1]).not_to be_nil
+      end
+    end
+
+    context 'when not given a block' do
+      it 'returns a configuration object' do
+        expect(subject.configure).to respond_to(:[], :[]=)
+      end
+    end
+
+    it 'allows configuring the api' do
+      subject.configure do |config|
+        config[:hello] = 'hello'
+        config[:bread] = 'bread'
+      end
+
+      subject.get '/hello-bread' do
+        "#{configuration[:hello]} #{configuration[:bread]}"
+      end
+
+      get '/hello-bread'
+      expect(last_response.body).to eq 'hello bread'
+    end
+  end
+
   context 'catch-all' do
     before do
       api1 = Class.new(Grape::API)