Rescue StandardError from explicit values validator procs (#1679)

* Rescue StandardError from explicit values validator procs

* Update CHANGELOG.md

* Update CHANGELOG.md

* Code Review feedback

* Code Review feedback

Author: jlfaber

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 * [#1652](https://github.com/ruby-grape/grape/pull/1652): Fix missing backtrace that was not being bubbled up to the `error_formatter` - [@dcsg](https://github.com/dcsg).
 * [#1661](https://github.com/ruby-grape/grape/pull/1661): Handle deeply-nested dependencies correctly - [@rnubel](https://github.com/rnubel), [@jnardone](https://github.com/jnardone).
+* [#1679](https://github.com/ruby-grape/grape/pull/1679): Treat StandardError from explicit values validator proc as false - [@jlfaber](https://github.com/jlfaber).
 
 ### 1.0.0 (7/3/2017)
 

README.md

@@ -1179,7 +1179,8 @@ end
 
 Alternatively, a Proc with arity one (i.e. taking one argument) can be used to explicitly validate
 each parameter value.  In that case, the Proc is expected to return a truthy value if the parameter
-value is valid.
+value is valid. The parameter will be considered invalid if the Proc returns a falsy value or if it
+raises a StandardError.
 
 ```ruby
 params do

lib/grape/validations/validators/values.rb

@@ -32,18 +32,23 @@ def validate_param!(attr_name, params)
           unless check_excepts(param_array)
 
         raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: message(:values) \
-          unless check_values(param_array)
+          unless check_values(param_array, attr_name)
 
         raise Grape::Exceptions::Validation, params: [@scope.full_name(attr_name)], message: message(:values) \
           if @proc && !param_array.all? { |param| @proc.call(param) }
       end
 
       private
 
-      def check_values(param_array)
+      def check_values(param_array, attr_name)
         values = @values.is_a?(Proc) && @values.arity.zero? ? @values.call : @values
         return true if values.nil?
-        return param_array.all? { |param| values.call(param) } if values.is_a? Proc
+        begin
+          return param_array.all? { |param| values.call(param) } if values.is_a? Proc
+        rescue StandardError => e
+          warn "Error '#{e}' raised while validating attribute '#{attr_name}'"
+          return false
+        end
         param_array.all? { |param| values.include?(param) }
       end
 

spec/grape/validations/validators/values_spec.rb

@@ -110,6 +110,13 @@ class API < Grape::API
           { type: params[:type] }
         end
 
+        params do
+          requires :number, type: Integer, values: ->(v) { v > 0 }
+        end
+        get '/lambda_int_val' do
+          { number: params[:number] }
+        end
+
         params do
           requires :type, values: -> { [] }
         end
@@ -357,6 +364,24 @@ def app
     expect(last_response.body).to eq({ error: 'type does not have a valid value' }.to_json)
   end
 
+  it 'does not allow non-numeric string value for int value using lambda' do
+    get('/lambda_int_val', number: 'foo')
+    expect(last_response.status).to eq 400
+    expect(last_response.body).to eq({ error: 'number is invalid, number does not have a valid value' }.to_json)
+  end
+
+  it 'does not allow nil for int value using lambda' do
+    get('/lambda_int_val', number: nil)
+    expect(last_response.status).to eq 400
+    expect(last_response.body).to eq({ error: 'number does not have a valid value' }.to_json)
+  end
+
+  it 'allows numeric string for int value using lambda' do
+    get('/lambda_int_val', number: '3')
+    expect(last_response.status).to eq 200
+    expect(last_response.body).to eq({ number: 3 }.to_json)
+  end
+
   it 'allows value using lambda' do
     get('/lambda_val', type: 'valid-type1')
     expect(last_response.status).to eq 200