Merge pull request #2019 from stanhu/sh-respect-nil-values-multiple-types

Avoid coercing parameter with multiple types to an empty Array

Author: dblock

CHANGELOG.md

@@ -10,6 +10,7 @@
 #### Fixes
 
 * Your contribution here.
+* [#2019](https://github.com/ruby-grape/grape/pull/2018): Avoid coercing parameter with multiple types to an empty Array - [@stanhu](https://github.com/stanhu).
 
 ### 1.3.1 (2020/03/11)
 

lib/grape/validations/validators/coerce.rb

@@ -65,21 +65,21 @@ def valid_type?(val)
       end
 
       def coerce_value(val)
-        # define default values for structures, the dry-types lib which is used
-        # for coercion doesn't accept nil as a value, so it would fail
-        if val.nil?
-          return []      if type == Array || type.is_a?(Array)
-          return Set.new if type == Set
-          return {}      if type == Hash
-        end
-
-        converter.call(val)
-
+        val.nil? ? coerce_nil(val) : converter.call(val)
       # Some custom types might fail, so it should be treated as an invalid value
       rescue StandardError
         Types::InvalidValue.new
       end
 
+      def coerce_nil(val)
+        # define default values for structures, the dry-types lib which is used
+        # for coercion doesn't accept nil as a value, so it would fail
+        return []      if type == Array
+        return Set.new if type == Set
+        return {}      if type == Hash
+        val
+      end
+
       # Type to which the parameter will be coerced.
       #
       # @return [Class]

spec/grape/validations/validators/coerce_spec.rb

@@ -180,6 +180,23 @@ def self.parsed?(value)
         expect(last_response.body).to eq(integer_class_name)
       end
 
+      it 'String' do
+        subject.params do
+          requires :string, coerce: String
+        end
+        subject.get '/string' do
+          params[:string].class
+        end
+
+        get '/string', string: 45
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('String')
+
+        get '/string', string: nil
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('NilClass')
+      end
+
       it 'is a custom type' do
         subject.params do
           requires :uri, coerce: SecureURIOnly
@@ -647,6 +664,19 @@ def self.parsed?(value)
         expect(last_response.body).to eq('String')
       end
 
+      it 'respects nil values' do
+        subject.params do
+          optional :a, types: [File, String]
+        end
+        subject.get '/' do
+          params[:a].class.to_s
+        end
+
+        get '/', a: nil
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('NilClass')
+      end
+
       it 'fails when no coercion is possible' do
         subject.params do
           requires :a, types: [Boolean, Integer]