Support fail_fast param validation option

.rubocop_todo.yml

@@ -1,29 +1,29 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2016-09-11 17:59:25 +0900 using RuboCop version 0.39.0.
+# on 2016-09-28 13:52:41 +0200 using RuboCop version 0.39.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 42
+# Offense count: 41
 Metrics/AbcSize:
   Max: 44
 
 # Offense count: 1
 Metrics/BlockNesting:
   Max: 4
 
-# Offense count: 7
+# Offense count: 8
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 277
+  Max: 279
 
 # Offense count: 28
 Metrics/CyclomaticComplexity:
   Max: 14
 
-# Offense count: 933
+# Offense count: 955
 # Configuration parameters: AllowHeredoc, AllowURI, URISchemes.
 # URISchemes: http, https
 Metrics/LineLength:

CHANGELOG.md

@@ -5,6 +5,7 @@
 * [#1486](https://github.com/ruby-grape/grape/pull/1486): Implemented except in values validator - [@jonmchan](https://github.com/jonmchan).
 * [#1470](https://github.com/ruby-grape/grape/pull/1470): Drop support for ruby-2.0 - [@namusyaka](https://github.com/namusyaka).
 * [#1490](https://github.com/ruby-grape/grape/pull/1490): Switch to Ruby-2.x+ syntax - [@namusyaka](https://github.com/namusyaka).
+* [#1499](https://github.com/ruby-grape/grape/pull/1499): Support fail_fast param validation option - [@dgasper](https://github.com/dgasper).
 * Your contribution here.
 
 #### Fixes

README.md

@@ -1355,6 +1355,25 @@ subject.rescue_from Grape::Exceptions::ValidationErrors do |e|
 end
 ```
 
+Grape returns all validation and coercion errors found by default.
+To skip all subsequent validation checks when a specific param is found invalid, use `fail_fast: true`.
+
+The following example will not check if `:wine` is present unless it finds `:beer`.
+```ruby
+params do
+  required :beer, fail_fast: true
+  required :wine
+end
+```
+The result of empty params would be a single `Grape::Exceptions::ValidationErrors` error.
+
+Similarly, no regular expression test will be performed if `:blah` is blank in the following example.
+```ruby
+params do
+  required :blah, allow_blank: false, regexp: /blah/, fail_fast: true
+end
+```
+
 ### I18n
 
 Grape supports I18n for parameter-related error messages, but will fallback to English if

lib/grape/endpoint.rb

@@ -343,8 +343,10 @@ def run_validators(validators, request)
           validator.validate(request)
         rescue Grape::Exceptions::Validation => e
           validation_errors << e
+          break if validator.fail_fast?
         rescue Grape::Exceptions::ValidationArrayErrors => e
           validation_errors += e.errors
+          break if validator.fail_fast?
         end
       end
 

lib/grape/validations/params_scope.rb

@@ -230,20 +230,24 @@ def validates(attrs, validations)
         full_attrs = attrs.collect { |name| { name: name, full_name: full_name(name) } }
         @api.document_attribute(full_attrs, doc_attrs)
 
+        # slice out fail_fast attribute
+        opts = {}
+        opts[:fail_fast] = validations.delete(:fail_fast) || false
+
         # Validate for presence before any other validators
         if validations.key?(:presence) && validations[:presence]
-          validate('presence', validations[:presence], attrs, doc_attrs)
+          validate('presence', validations[:presence], attrs, doc_attrs, opts)
           validations.delete(:presence)
           validations.delete(:message) if validations.key?(:message)
         end
 
         # Before we run the rest of the validators, let's handle
         # whatever coercion so that we are working with correctly
         # type casted values
-        coerce_type validations, attrs, doc_attrs
+        coerce_type validations, attrs, doc_attrs, opts
 
         validations.each do |type, options|
-          validate(type, options, attrs, doc_attrs)
+          validate(type, options, attrs, doc_attrs, opts)
         end
       end
 
@@ -308,7 +312,7 @@ def check_coerce_with(validations)
       # composited from more than one +requires+/+optional+
       # parameter, and needs to be run before most other
       # validations.
-      def coerce_type(validations, attrs, doc_attrs)
+      def coerce_type(validations, attrs, doc_attrs, opts)
         check_coerce_with(validations)
 
         return unless validations.key?(:coerce)
@@ -318,7 +322,7 @@ def coerce_type(validations, attrs, doc_attrs)
           method: validations[:coerce_with],
           message: validations[:coerce_message]
         }
-        validate('coerce', coerce_options, attrs, doc_attrs)
+        validate('coerce', coerce_options, attrs, doc_attrs, opts)
         validations.delete(:coerce_with)
         validations.delete(:coerce)
         validations.delete(:coerce_message)
@@ -337,12 +341,12 @@ def check_incompatible_option_values(values, default)
         raise Grape::Exceptions::IncompatibleOptionValues.new(:default, default, :values, values)
       end
 
-      def validate(type, options, attrs, doc_attrs)
+      def validate(type, options, attrs, doc_attrs, opts)
         validator_class = Validations.validators[type.to_s]
 
         raise Grape::Exceptions::UnknownValidator.new(type) unless validator_class
 
-        value = validator_class.new(attrs, options, doc_attrs[:required], self)
+        value = validator_class.new(attrs, options, doc_attrs[:required], self, opts)
         @api.namespace_stackable(:validations, value)
       end
 

lib/grape/validations/validators/base.rb

@@ -10,11 +10,13 @@ class Base
       # @param options [Object] implementation-dependent Validator options
       # @param required [Boolean] attribute(s) are required or optional
       # @param scope [ParamsScope] parent scope for this Validator
-      def initialize(attrs, options, required, scope)
+      # @param opts [Hash] additional validation options
+      def initialize(attrs, options, required, scope, opts = {})
         @attrs = Array(attrs)
         @option = options
         @required = required
         @scope = scope
+        @fail_fast = opts[:fail_fast] || false
       end
 
       # Validates a given request.
@@ -76,6 +78,10 @@ def options_key?(key, options = nil)
         options = instance_variable_get(:@option) if options.nil?
         options.respond_to?(:key?) && options.key?(key) && !options[key].nil?
       end
+
+      def fail_fast?
+        @fail_fast
+      end
     end
   end
 end

lib/grape/validations/validators/default.rb

@@ -1,7 +1,7 @@
 module Grape
   module Validations
     class DefaultValidator < Base
-      def initialize(attrs, options, required, scope)
+      def initialize(attrs, options, required, scope, opts = {})
         @default = options
         super
       end

lib/grape/validations/validators/values.rb

@@ -1,7 +1,7 @@
 module Grape
   module Validations
     class ValuesValidator < Base
-      def initialize(attrs, options, required, scope)
+      def initialize(attrs, options, required, scope, opts = {})
         @excepts = (options_key?(:except, options) ? options[:except] : [])
         @values = (options_key?(:value, options) ? options[:value] : [])
 

spec/grape/validations/params_scope_spec.rb

@@ -584,4 +584,44 @@ def initialize(value)
     get '/nested', bar: { a: 'x', c: { b: 'yes' } }
     expect(JSON.parse(last_response.body)).to eq('bar' => { 'a' => 'x', 'c' => { 'b' => 'yes' } })
   end
+
+  context 'failing fast' do
+    context 'when fail_fast is not defined' do
+      it 'does not stop validation' do
+        subject.params do
+          requires :one
+          requires :two
+          requires :three
+        end
+        subject.get('/fail-fast') { declared(params).to_json }
+
+        get '/fail-fast'
+        expect(last_response.status).to eq(400)
+        expect(last_response.body).to eq('one is missing, two is missing, three is missing')
+      end
+    end
+    context 'when fail_fast is defined it stops the validation' do
+      it 'of other params' do
+        subject.params do
+          requires :one, fail_fast: true
+          requires :two
+        end
+        subject.get('/fail-fast') { declared(params).to_json }
+
+        get '/fail-fast'
+        expect(last_response.status).to eq(400)
+        expect(last_response.body).to eq('one is missing')
+      end
+      it 'for a single param' do
+        subject.params do
+          requires :one, allow_blank: false, regexp: /[0-9]+/, fail_fast: true
+        end
+        subject.get('/fail-fast') { declared(params).to_json }
+
+        get '/fail-fast', one: ''
+        expect(last_response.status).to eq(400)
+        expect(last_response.body).to eq('one is empty')
+      end
+    end
+  end
 end