Address ruby-grape#543 - raise proper validation errors on array/hash…

… types

 * Also adds a :type option to group/requires/optional with block,
   which can either be Array or Hash. It defaults to Array.

 * Fixes (2) and (3) as mentioned in ruby-grape#543

 * There is a quirk around query parameters: an empty array should
   pass validation if the array itself is required, but with how
   query parameters work, it doesn't. It does work fine with body
   parameters using JSON or similar, which do have a concept of an
   empty array.

lib/grape.rb

@@ -6,6 +6,7 @@
 require 'rack/auth/basic'
 require 'rack/auth/digest/md5'
 require 'hashie'
+require 'set'
 require 'active_support/core_ext/hash/indifferent_access'
 require 'active_support/ordered_hash'
 require 'active_support/core_ext/object/conversions'

lib/grape/validations.rb

@@ -91,6 +91,7 @@ def initialize(opts, &block)
         @parent   = opts[:parent]
         @api      = opts[:api]
         @optional = opts[:optional] || false
+        @type     = opts[:type]
         @declared_params = []
 
         instance_eval(&block)
@@ -99,29 +100,35 @@ def initialize(opts, &block)
       end
 
       def should_validate?(parameters)
-        return false if @optional && params(parameters).all?(&:blank?)
+        return false if @optional && params(parameters).respond_to?(:'all?') && params(parameters).all?(&:blank?)
         return true if parent.nil?
         parent.should_validate?(parameters)
       end
 
       def requires(*attrs, &block)
-        return new_scope(attrs, &block) if block_given?
+        orig_attrs = attrs.clone
 
         validations = { presence: true }
         validations.merge!(attrs.pop) if attrs.last.is_a?(Hash)
+        validations[:type] ||= Array if block_given?
+        validates(attrs, validations)
+
+        return new_scope(orig_attrs, &block) if block_given?
 
         push_declared_params(attrs)
-        validates(attrs, validations)
       end
 
       def optional(*attrs, &block)
-        return new_scope(attrs, true, &block) if block_given?
+        orig_attrs = attrs
 
         validations = {}
         validations.merge!(attrs.pop) if attrs.last.is_a?(Hash)
+        validations[:type] ||= Array if block_given?
+        validates(attrs, validations)
+
+        return new_scope(orig_attrs, true, &block) if block_given?
 
         push_declared_params(attrs)
-        validates(attrs, validations)
       end
 
       def group(element, &block)
@@ -132,9 +139,11 @@ def params(params)
         params = @parent.params(params) if @parent
         if @element
           if params.is_a?(Array)
-            params = params.map { |el| el[@element] || {} }
-          else
+            params = params.map { |el| el[@element] || {} }.flatten
+          elsif params.is_a?(Hash)
             params = params[@element] || {}
+          else
+            params = {}
           end
         end
         params
@@ -154,8 +163,9 @@ def push_declared_params(attrs)
       private
 
       def new_scope(attrs, optional = false, &block)
-        raise ArgumentError unless attrs.size == 1
-        ParamsScope.new(api: @api, element: attrs.first, parent: self, optional: optional, &block)
+        opts = attrs[1] || { :type => Array }
+        raise ArgumentError unless opts.keys.to_set.subset? [ :type ].to_set
+        ParamsScope.new(api: @api, element: attrs.first, parent: self, optional: optional, type: opts[:type], &block)
       end
 
       # Pushes declared params to parent or settings
@@ -237,7 +247,7 @@ def reset_validations!
       end
 
       def params(&block)
-        ParamsScope.new(api: self, &block)
+        ParamsScope.new(api: self, type: Hash, &block)
       end
 
       def document_attribute(names, opts)

lib/grape/validations/coerce.rb

@@ -6,6 +6,7 @@ class API
   module Validations
     class CoerceValidator < SingleOptionValidator
       def validate_param!(attr_name, params)
+        raise Grape::Exceptions::Validation, param: @scope.full_name(attr_name), message_key: :coerce unless params.is_a? Hash
         new_value = coerce_value(@option, params[attr_name])
         if valid_type?(new_value)
           params[attr_name] = new_value
@@ -45,6 +46,10 @@ def valid_type?(val)
       end
 
       def coerce_value(type, val)
+        # Don't coerce things other than nil to Arrays or Hashes
+        return val || [] if type == Array
+        return val || {} if type == Hash
+
         converter = Virtus::Attribute.build(type)
         converter.coerce(val)
 

lib/grape/validations/presence.rb

@@ -7,7 +7,7 @@ def validate!(params)
       end
 
       def validate_param!(attr_name, params)
-        unless params.has_key?(attr_name)
+        unless params.respond_to? :'has_key?' and params.has_key?(attr_name)
           raise Grape::Exceptions::Validation, param: @scope.full_name(attr_name), message_key: :presence
         end
       end