BigDecimal coercion (#1971)

Mapping for BigDecimal to DryTypes::Coercible::Decimal for coercion

CHANGELOG.md

@@ -6,7 +6,7 @@
 
 #### Fixes
 
-* Your contribution here.
+* [#1971](https://github.com/ruby-grape/grape/pull/1971): Fix BigDecimal coercion - [@FlickStuart](https://github.com/FlickStuart).
 * [#1968](https://github.com/ruby-grape/grape/pull/1968): Fix args forwarding in Grape::Middleware::Stack#merge_with for ruby 2.7.0 - [@dm1try](https://github.com/dm1try).
 
 ### 1.3.0 (2020/01/11)

lib/grape/validations/types/primitive_coercer.rb

@@ -12,11 +12,13 @@ class PrimitiveCoercer < DryTypeCoercer
           Grape::API::Boolean => DryTypes::Params::Bool,
 
           # unfortunatelly, a +Params+ scope doesn't contain String
-          String              => DryTypes::Coercible::String
+          String              => DryTypes::Coercible::String,
+          BigDecimal          => DryTypes::Coercible::Decimal
         }.freeze
 
         STRICT_MAPPING = {
-          Grape::API::Boolean => DryTypes::Strict::Bool
+          Grape::API::Boolean => DryTypes::Strict::Bool,
+          BigDecimal          => DryTypes::Strict::Decimal
         }.freeze
 
         def initialize(type, strict = false)

spec/grape/validations/validators/coerce_spec.rb

@@ -154,6 +154,19 @@ def self.parsed?(value)
     end
 
     context 'coerces' do
+      it 'BigDecimal' do
+        subject.params do
+          requires :bigdecimal, coerce: BigDecimal
+        end
+        subject.get '/bigdecimal' do
+          params[:bigdecimal].class
+        end
+
+        get '/bigdecimal', bigdecimal: '45'
+        expect(last_response.status).to eq(200)
+        expect(last_response.body).to eq('BigDecimal')
+      end
+
       it 'Integer' do
         subject.params do
           requires :int, coerce: Integer