Provides Array index context in errors.

CHANGELOG.md

@@ -5,6 +5,7 @@
 
 * Your contribution here.
 
+* [#1218](https://github.com/ruby-grape/grape/pull/1218): Provide array index context in errors - [@towanda](https://github.com/towanda).
 * [#1196](https://github.com/ruby-grape/grape/pull/1196): Allow multiple `before_each` blocks - [@huynhquancam](https://github.com/huynhquancam).
 * [#1190](https://github.com/ruby-grape/grape/putt/1190): Bypass formatting for statuses with no entity-body - [@tylerdooling](https://github.com/tylerdooling).
 * [#1188](https://github.com/ruby-grape/grape/putt/1188): Allow parameters with more than one type - [@dslh](https://github.com/dslh).

lib/grape/validations/attributes_iterator.rb

@@ -3,14 +3,20 @@ module Validations
     class AttributesIterator
       include Enumerable
 
+      attr_reader :scope
+
       def initialize(validator, scope, params)
+        @scope = scope
         @attrs = validator.attrs
         @params = Array.wrap(scope.params(params))
       end
 
       def each
         @params.each do |resource_params|
-          @attrs.each do |attr_name|
+          @attrs.each_with_index do |attr_name, index|
+            if resource_params.is_a?(Hash) && resource_params[attr_name].is_a?(Array)
+              scope.index = index
+            end
             yield resource_params, attr_name
           end
         end

lib/grape/validations/params_scope.rb

@@ -1,7 +1,7 @@
 module Grape
   module Validations
     class ParamsScope
-      attr_accessor :element, :parent
+      attr_accessor :element, :parent, :index
 
       include Grape::DSL::Parameters
 
@@ -46,7 +46,7 @@ def full_name(name)
         case
         when nested?
           # Find our containing element's name, and append ours.
-          "#{@parent.full_name(@element)}[#{name}]"
+          "#{@parent.full_name(@element)}#{parent_index}[#{name}]"
         when lateral?
           # Find the name of the element as if it was at the
           # same nesting level as our parent.
@@ -57,6 +57,10 @@ def full_name(name)
         end
       end
 
+      def parent_index
+        "[#{@parent.index}]" if @parent.present? && @parent.index.present?
+      end
+
       # @return [Boolean] whether or not this scope is the root-level scope
       def root?
         !@parent

spec/grape/validations/validators/coerce_spec.rb

@@ -293,7 +293,7 @@ class User
 
         get '/ints', ints: '{"i":1,"j":"2"}'
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('ints[i] is missing, ints[i] is invalid, ints[j] is missing')
+        expect(last_response.body).to eq('ints[0][i] is missing, ints[0][i] is invalid, ints[0][j] is missing')
 
         get '/ints', ints: '[{"i":"1","j":"2"}]'
         expect(last_response.status).to eq(200)

spec/grape/validations_spec.rb

@@ -337,7 +337,7 @@ def define_requires_none
 
         get '/required', items: [{ key: 'hash in array' }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items is invalid, items[key] does not have a valid value')
+        expect(last_response.body).to eq('items is invalid, items[0][key] does not have a valid value')
       end
 
       it 'works when all params match' do
@@ -492,7 +492,7 @@ def validate_param!(attr_name, params)
         # NOTE: with body parameters in json or XML or similar this
         # should actually fail with: children[parents][name] is missing.
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('children[parents] is missing')
+        expect(last_response.body).to eq('children[0][parents] is missing')
       end
 
       it 'safely handles empty arrays and blank parameters' do
@@ -503,7 +503,7 @@ def validate_param!(attr_name, params)
         expect(last_response.body).to eq('children is missing')
         get '/within_array', children: [name: 'Jay']
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('children[parents] is missing')
+        expect(last_response.body).to eq('children[0][parents] is missing')
       end
 
       it 'errors when param is not an Array' do
@@ -518,7 +518,7 @@ def validate_param!(attr_name, params)
 
         get '/within_array', children: [name: 'Jay', parents: { name: 'Fred' }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('children[parents] is invalid')
+        expect(last_response.body).to eq('children[0][parents] is invalid')
       end
     end
 
@@ -644,15 +644,15 @@ def validate_param!(attr_name, params)
           { name: 'Job', parents: [{ name: 'Joy' }] }
         ]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('children[parents][name] is missing')
+        expect(last_response.body).to eq('children[0][parents][0][name] is missing')
       end
 
       it 'safely handles empty arrays and blank parameters' do
         put_with_json '/within_array', children: []
         expect(last_response.status).to eq(200)
         put_with_json '/within_array', children: [name: 'Jay']
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('children[parents] is missing')
+        expect(last_response.body).to eq('children[0][parents] is missing')
       end
     end
 
@@ -683,7 +683,7 @@ def validate_param!(attr_name, params)
       it 'errors when group is present, but required param is not' do
         get '/optional_group', items: [{ not_key: 'foo' }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items[key] is missing')
+        expect(last_response.body).to eq('items[0][key] is missing')
       end
 
       it "errors when param is present but isn't an Array" do
@@ -727,7 +727,7 @@ def validate_param!(attr_name, params)
       it 'does internal validations if the outer group is present' do
         get '/nested_optional_group', items: [{ key: 'foo' }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items[required_subitems] is missing')
+        expect(last_response.body).to eq('items[0][required_subitems] is missing')
 
         get '/nested_optional_group', items: [{ key: 'foo', required_subitems: [{ value: 'bar' }] }]
         expect(last_response.status).to eq(200)
@@ -737,7 +737,7 @@ def validate_param!(attr_name, params)
       it 'handles deep nesting' do
         get '/nested_optional_group', items: [{ key: 'foo', required_subitems: [{ value: 'bar' }], optional_subitems: [{ not_value: 'baz' }] }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items[optional_subitems][value] is missing')
+        expect(last_response.body).to eq('items[0][optional_subitems][0][value] is missing')
 
         get '/nested_optional_group', items: [{ key: 'foo', required_subitems: [{ value: 'bar' }], optional_subitems: [{ value: 'baz' }] }]
         expect(last_response.status).to eq(200)
@@ -747,15 +747,15 @@ def validate_param!(attr_name, params)
       it 'handles validation within arrays' do
         get '/nested_optional_group', items: [{ key: 'foo' }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items[required_subitems] is missing')
+        expect(last_response.body).to eq('items[0][required_subitems] is missing')
 
         get '/nested_optional_group', items: [{ key: 'foo', required_subitems: [{ value: 'bar' }] }]
         expect(last_response.status).to eq(200)
         expect(last_response.body).to eq('nested optional group works')
 
         get '/nested_optional_group', items: [{ key: 'foo', required_subitems: [{ value: 'bar' }], optional_subitems: [{ not_value: 'baz' }] }]
         expect(last_response.status).to eq(400)
-        expect(last_response.body).to eq('items[optional_subitems][value] is missing')
+        expect(last_response.body).to eq('items[0][optional_subitems][0][value] is missing')
       end
 
       it 'adds to declared parameters' do