如何使用Ruby Grape实体自定义格式属性？

Question

我有一个属性价格在我的模型，目前它正在格式化科学记数法，我宁愿显示十进制符号。

ruby-grape提出了定制下面的代码格式化字段：

class ExampleEntity < Grape::Entity 
    expose :formatted_value 
    # ... 
private 

    def formatted_value 
    "+ X #{object.value}" 
    end 
end 

不过，我已经注意到，值，这是对象的属性，是不是在这个范围内都有效。这里＃的输出{} object.methods：

[ 
{ 
"price": "0.12E3", 
"formatted_value": "+ X [:rehash, :to_hash, :to_h, :to_a, :inspect, :to_s, :==, :[], :hash, :eql?, :fetch, :[]=, :store, :default, :default=,  :default_proc, :default_proc=, :key, :index, :size, :length, :empty?,  :each_value, :each_key, :each_pair, :each, :keys, :values, :values_at, :shift, :delete, :delete_if, :keep_if, :select, :select!, :reject, :reject!, :clear, :invert, :update, :replace, :merge!, :merge, :assoc, :rassoc, :flatten, :include?, :member?, :has_key?, :has_value?, :key?, :value?, :compare_by_identity, :compare_by_identity?, :any?, :transform_keys, :transform_keys!, :stringify_keys, :stringify_keys!, :symbolize_keys, :to_options, :symbolize_keys!, :to_options!, :assert_valid_keys, :deep_transform_keys, :deep_transform_keys!, :deep_stringify_keys, :deep_stringify_keys!, :deep_symbolize_keys, :deep_symbolize_keys!, :reverse_merge, :reverse_merge!, :reverse_update, :with_indifferent_access, :nested_under_indifferent_access, :blank?, :extractable_options?, :deep_merge, :deep_merge!, :except, :except!, :slice, :slice!, :extract!, :to_query, :to_param, :to_xml, :to_json, :entries, :sort, :sort_by, :grep, :count, :find, :detect, :find_index, :find_all, :collect, :map, :flat_map, :collect_concat, :inject, :reduce, :partition, :group_by, :first, :all?, :one?, :none?, :min, :max, :minmax, :min_by, :max_by, :minmax_by, :each_with_index, :reverse_each, :each_entry, :each_slice, :each_cons, :each_with_object, :zip, :take, :take_while, :drop, :drop_while, :cycle, :chunk, :slice_before, :slice_after, :slice_when, :lazy, :to_set, :present?, :presence, :acts_like?, :try, :try!, :psych_to_yaml, :to_yaml, :to_yaml_properties, :nil?, :===, :=~, :!~, :<=>, :class, :singleton_class, :clone, :dup, :itself, :taint, :tainted?, :untaint, :untrust, :untrusted?, :trust, :freeze, :frozen?, :methods, :singleton_methods, :protected_methods, :private_methods, :public_methods, :instance_variables, :instance_variable_get, :instance_variable_set, :instance_variable_defined?, :remove_instance_variable, :instance_of?, :kind_of?, :is_a?, :tap, :send, :public_send, :respond_to?, :extend, :display, :method, :public_method, :singleton_method, :define_singleton_method, :object_id, :to_enum, :enum_for, :class_eval, :silence_warnings, :enable_warnings, :with_warnings, :silence_stderr, :silence_stream, :suppress, :capture, :silence, :quietly, :equal?, :!, :!=, :instance_eval, :instance_exec, :__send__, :__id__]" 
} 
] 

所以下面的代码抛出我{ “错误”：“未定义的方法'价格”的哈希：0x0055a87576f660" }

def formatted_price 
"#{object.price}" 
end 

Answer 1

由于异常说，暴露的对象是一个散列。因此，可以使用对象[：value]而不是object.value来查找属性，如下所示

 private 
      def formatted_price 
      "%f" % "#{object[:price]}" 
      end 
     end