Added all_or_none parameter validator.

CHANGELOG.md

@@ -1,6 +1,6 @@
 0.9.1 (Next)
 ============
-
+* [#803](https://github.com/intridea/grape/pull/803): Added `all_or_none_of` parameter validator - [@loveltyoic](https://github.com/loveltyoic).
 * [#774](https://github.com/intridea/grape/pull/774): Extended `mutually_exclusive`, `exactly_one_of`, `at_least_one_of` to work inside any kind of group: `requires` or `optional`, `Hash` or `Array` - [@ShPakvel](https://github.com/ShPakvel).
 * [#743](https://github.com/intridea/grape/pull/743): Added `allow_blank` parameter validator to validate non-empty strings - [@elado](https://github.com/elado).
 * [#745](https://github.com/intridea/grape/pull/745): Removed `atom+xml`, `rss+xml`, and `jsonapi` content-types - [@akabraham](https://github.com/akabraham).

README.md

@@ -643,7 +643,20 @@ params do
 end
 ```
 
-#### Nested `mutually_exclusive`, `exactly_one_of`, `at_least_one_of`
+#### `all_or_none_of`
+
+Parameters can be defined as 'all_or_none_of', ensuring that all or none of parameters gets selected.
+
+```ruby
+params do
+  optional :beer
+  optional :wine
+  optional :juice
+  all_or_none_of :beer, :wine, :juice
+end
+```
+
+#### Nested `mutually_exclusive`, `exactly_one_of`, `at_least_one_of`, `all_or_none_of`
 
 All of these methods can be used at any nested level.
 
@@ -666,6 +679,11 @@ params do
     optional :icecream
     mutually_exclusive :cake, :icecream
   end
+  optional :recipe do 
+    optional :oil
+    optional :meat
+    all_or_none_of :oil, :meat
+  end
 end
 ```
 

lib/grape.rb

@@ -138,5 +138,6 @@ class API
 require 'grape/validations/validators/regexp'
 require 'grape/validations/validators/values'
 require 'grape/validations/params_scope'
+require 'grape/validations/validators/all_or_none'
 
 require 'grape/version'

lib/grape/locale/en.yml

@@ -32,4 +32,5 @@ en:
         mutual_exclusion: 'are mutually exclusive'
         at_least_one: 'are missing, at least one parameter must be provided'
         exactly_one: 'are missing, exactly one parameter must be provided'
+        all_or_none: 'provide all or none of parameters'
 

lib/grape/validations/validators/all_or_none.rb

@@ -0,0 +1,20 @@
+module Grape
+  module Validations
+    require 'grape/validations/validators/multiple_params_base'
+    class AllOrNoneOfValidator < MultipleParamsBase
+      def validate!(params)
+        super
+        if scope_requires_params && only_subset_present
+          raise Grape::Exceptions::Validation, params: all_keys, message_key: :all_or_none
+        end
+        params
+      end
+
+      private
+
+      def only_subset_present
+        scoped_params.any? { |resource_params| keys_in_common(resource_params).length > 0 && keys_in_common(resource_params).length < attrs.length  }
+      end
+    end
+  end
+end

spec/grape/validations/validators/all_or_none_spec.rb

@@ -0,0 +1,61 @@
+require 'spec_helper'
+
+describe Grape::Validations::AllOrNoneOfValidator do
+  describe '#validate!' do
+    let(:scope) do
+      Struct.new(:opts) do
+        def params(arg)
+          arg
+        end
+
+        def required?; end
+      end
+    end
+    let(:all_or_none_params) { [:beer, :wine, :grapefruit] }
+    let(:validator) { described_class.new(all_or_none_params, {}, false, scope.new) }
+
+    context 'when all restricted params are present' do
+      let(:params) { { beer: true, wine: true, grapefruit: true } }
+
+      it 'does not raise a validation exception' do
+        expect(validator.validate!(params)).to eql params
+      end
+
+      context 'mixed with other params' do
+        let(:mixed_params) { params.merge!(other: true, andanother: true) }
+
+        it 'does not raise a validation exception' do
+          expect(validator.validate!(mixed_params)).to eql mixed_params
+        end
+      end
+    end
+
+    context 'when none of the restricted params is selected' do
+      let(:params) { { somethingelse: true } }
+
+      it 'does not raise a validation exception' do
+        expect(validator.validate!(params)).to eql params
+      end
+    end
+
+    context 'when only a subset of restricted params are present' do
+      let(:params) { { beer: true, grapefruit: true } }
+
+      it 'raises a validation exception' do
+        expect {
+          validator.validate! params
+        }.to raise_error(Grape::Exceptions::Validation)
+      end
+      context 'mixed with other params' do
+        let(:mixed_params) { params.merge!(other: true, andanother: true) }
+
+        it 'raise a validation exception' do
+          expect {
+            validator.validate! params
+          }.to raise_error(Grape::Exceptions::Validation)
+        end
+      end
+    end
+
+  end
+end