Params: Fix coerce_with helper and Arrays types

CHANGELOG.md

@@ -9,6 +9,8 @@
 
 #### Fixes
 
+* [#1325](https://github.com/ruby-grape/grape/pull/1325): Params: Fix coerce_with helper with Array types - [@ngonzalez](https://github.com/ngonzalez).
+
 0.15.0 (3/8/2016)
 =================
 

README.md

@@ -797,6 +797,15 @@ params do
 end
 ```
 
+Example of use of `coerce_with` with a lambda (a class with a `parse` method could also have been used)
+It will parse a string and return an Array of Integers, matching the `Array[Integer]` `type`.
+
+```ruby
+params do
+  requires :values, type: Array[Integer], coerce_with: ->(val) { val.split(/\s+/).map(&:to_i) }
+end
+```
+
 ### Multipart File Parameters
 
 Grape makes use of `Rack::Request`'s built-in support for multipart

lib/grape/validations/types/custom_type_coercer.rb

@@ -136,6 +136,8 @@ def infer_type_check(type)
             # Note that this will fail unless a method is also
             # passed, or if the type also implements a parse() method.
             type
+          elsif type.is_a?(Enumerable)
+            ->(value) { value.all? { |item| item.is_a? type[0] } }
           else
             # By default, do a simple type check
             ->(value) { value.is_a? type }

spec/grape/validations/validators/coerce_spec.rb

@@ -331,6 +331,57 @@ class User
     end
 
     context 'using coerce_with' do
+      it 'parses parameters with Array type' do
+        subject.params do
+          requires :values, type: Array, coerce_with: ->(val) { val.split(/\s+/).map(&:to_i) }
+        end
+        subject.get '/ints' do
+          params[:values]
+        end
+
+        get '/ints', values: '1 2 3 4'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq([1, 2, 3, 4])
+
+        get '/ints', values: 'a b c d'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq([0, 0, 0, 0])
+      end
+
+      it 'parses parameters with Array[String] type' do
+        subject.params do
+          requires :values, type: Array[String], coerce_with: ->(val) { val.split(/\s+/).map(&:to_i) }
+        end
+        subject.get '/ints' do
+          params[:values]
+        end
+
+        get '/ints', values: '1 2 3 4'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq(%w(1 2 3 4))
+
+        get '/ints', values: 'a b c d'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq(%w(0 0 0 0))
+      end
+
+      it 'parses parameters with Array[Integer] type' do
+        subject.params do
+          requires :values, type: Array[Integer], coerce_with: ->(val) { val.split(/\s+/).map(&:to_i) }
+        end
+        subject.get '/ints' do
+          params[:values]
+        end
+
+        get '/ints', values: '1 2 3 4'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq([1, 2, 3, 4])
+
+        get '/ints', values: 'a b c d'
+        expect(last_response.status).to eq(200)
+        expect(JSON.parse(last_response.body)).to eq([0, 0, 0, 0])
+      end
+
       it 'uses parse where available' do
         subject.params do
           requires :ints, type: Array, coerce_with: JSON do