Fix usage of exactly_one_of in shared params

Author: milgner

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#1755](https://github.com/ruby-grape/grape/pull/1755): Fix shared params with exactly_one_of - [@milgner](https://github.com/milgner).
 * [#1740](https://github.com/ruby-grape/grape/pull/1740): Fix dependent parameter validation using `given` when parameter is a `Hash` - [@jvortmann](https://github.com/jvortmann).
 * [#1737](https://github.com/ruby-grape/grape/pull/1737): Fix translating error when passing symbols as params in custom validations - [@mlzhuyi](https://github.com/mlzhuyi).
 * [#1749](https://github.com/ruby-grape/grape/pull/1749): Allow rescue from non-`StandardError` exceptions - [@dm1try](https://github.com/dm1try).

lib/grape/validations/params_scope.rb

@@ -40,7 +40,7 @@ def initialize(opts, &block)
       #   validated
       def should_validate?(parameters)
         return false if @optional && (params(parameters).blank? || all_element_blank?(parameters))
-
+        return false unless meets_dependency?(params(parameters), parameters)
         return true if parent.nil?
         parent.should_validate?(parameters)
       end
@@ -51,7 +51,7 @@ def meets_dependency?(params, request_params)
         end
 
         return true unless @dependent_on
-
+        return params.any? { |param| meets_dependency?(param, request_params) } if params.is_a?(Array)
         params = params.with_indifferent_access
 
         @dependent_on.each do |dependency|

spec/grape/api/shared_helpers_exactly_one_of_spec.rb

@@ -0,0 +1,47 @@
+require 'spec_helper'
+
+describe Grape::API::Helpers do
+  subject do
+    shared_params = Module.new do
+      extend Grape::API::Helpers
+
+      params :drink do
+        optional :beer
+        optional :wine
+        exactly_one_of :beer, :wine
+      end
+    end
+
+    Class.new(Grape::API) do
+      helpers shared_params
+      format :json
+
+      params do
+        requires :orderType, type: String, values: %w[food drink]
+        given orderType: ->(val) { val == 'food' } do
+          optional :pasta
+          optional :pizza
+          exactly_one_of :pasta, :pizza
+        end
+        given orderType: ->(val) { val == 'drink' } do
+          use :drink
+        end
+      end
+      get do
+        declared(params, include_missing: true)
+      end
+    end
+  end
+
+  def app
+    subject
+  end
+
+  it 'defines parameters' do
+    get '/', orderType: 'food', pizza: 'mista'
+    expect(last_response.status).to eq 200
+    expect(last_response.body).to eq({ orderType: 'food',
+                                       pasta: nil, pizza: 'mista',
+                                       beer: nil, wine: nil }.to_json)
+  end
+end