allow required param with predefined set of values to be nil inside optional group

CHANGELOG.md

@@ -12,6 +12,7 @@ Next Release
 
 #### Fixes
 
+* [#671](https://github.com/intridea/grape/pull/671): Allow required param with predefined set of values to be nil inside optional group - [@dm1try](https://github.com/dm1try).
 * [#651](https://github.com/intridea/grape/pull/651): The `rescue_from` keyword now properly defaults to rescuing subclasses of exceptions - [@xevix](https://github.com/xevix).
 * [#614](https://github.com/intridea/grape/pull/614): Params with `nil` value are now refused by `RegexpValidator` - [@dm1try](https://github.com/dm1try).
 * [#494](https://github.com/intridea/grape/issues/494): Fixed performance issue with requests carrying a large payload - [@dblock](https://github.com/dblock).

lib/grape/validations.rb

@@ -174,6 +174,10 @@ def full_name(name)
  name.to_s
  end
 
+ def root?
+ !@parent
+ end
+
  protected
 
  def push_declared_params(attrs)

lib/grape/validations/values.rb

@@ -8,10 +8,16 @@ def initialize(attrs, options, required, scope)
  end
 
  def validate_param!(attr_name, params)
- if (params[attr_name] || @required) && !(@values.is_a?(Proc) ? @values.call : @values).include?(params[attr_name])
+ if (params[attr_name] || required_for_root_scope?) && !(@values.is_a?(Proc) ? @values.call : @values).include?(params[attr_name])
  raise Grape::Exceptions::Validation, param: @scope.full_name(attr_name), message_key: :values
  end
  end
+
+ private
+
+ def required_for_root_scope?
+ @required && @scope.root?
+ end
  end
  end
 end

spec/grape/validations/values_spec.rb

@@ -49,6 +49,13 @@ class API < Grape::API
  get '/values/coercion' do
  { type: params[:type] }
  end
+
+ params do
+ optional :optional do
+ requires :type, values: ["a", "b"]
+ end
+ end
+ get '/optional_with_required_values'
  end
  end
  end
@@ -69,10 +76,17 @@ def app
  expect(last_response.body).to eq({ error: "type does not have a valid value" }.to_json)
  end
 
- it 'does not allow nil value for a parameter' do
- get("/", type: nil)
- expect(last_response.status).to eq 400
- expect(last_response.body).to eq({ error: "type does not have a valid value" }.to_json)
+ context 'nil value for a parameter' do
+ it 'does not allow for root params scope' do
+ get("/", type: nil)
+ expect(last_response.status).to eq 400
+ expect(last_response.body).to eq({ error: "type does not have a valid value" }.to_json)
+ end
+
+ it 'allows for a required param in child scope' do
+ get('/optional_with_required_values')
+ expect(last_response.status).to eq 200
+ end
  end
 
  it 'allows a valid default value' do