如何访问RubyOnrails中的查询集合中的特定对象

我是rubyonrails的新手。现在正在为Shopify项目工作。我从我的桌子上收集了一个集合，我无法在视图中打印任何特定的字段值。如何访问RubyOnrails中的查询集合中的特定对象

My Query in controller（its helper method）。

def getcustomoptions product_id 
    customoptions = Productoption.where(product_id: product_id).first 
    return ActiveSupport::JSON.encode(customoptions) 
end 

helper_method :getcustomoptions

而且在我看来，当我调试视图中的输出，

pdtoption = getcustomoptions(option.id) 
debug pdtoption

是

{"id":3,"product_id":10647391438,"front_preview":"tomrain.s3.eu-central-1.amazonaws.com/productoptions/front_previews/000/000/003/original/collar-green-front.png?1496132797","left_side_preview":"tomrain.s3.eu-central-1.amazonaws.com/productoptions/left_side_previews/000/000/003/original/t-shirt-left-side.jpg?1496132798","back_preview":"tomrain.s3.eu-central-1.amazonaws.com/productoptions/back_previews/000/000/003/original/collar-green-back.png?1496132798","right_side_preview":"tomrain.s3.eu-central-1.amazonaws.com/productoptions/right_side_previews/000/000/003/original/tshirt-brightlights-side.jpg?1496132798","front_preview_file_name":"collar-green-front.png","front_preview_content_type":"image/png","front_preview_file_size":275338,"front_preview_updated_at":"2017-05-30T08:26:37.864Z","left_side_preview_file_name":"t-shirt-left-side.jpg","left_side_preview_content_type":"image/jpeg","left_side_preview_file_size":79742,"left_side_preview_updated_at":"2017-05-30T08:26:38.280Z","back_preview_file_name":"collar-green-back.png","back_preview_content_type":"image/png","back_preview_file_size":250070,"back_preview_updated_at":"2017-05-30T08:26:38.437Z","right_side_preview_file_name":"tshirt-brightlights-side.jpg","right_side_preview_content_type":"image/jpeg","right_side_preview_file_size":56997,"right_side_preview_updated_at":"2017-05-30T08:26:38.618Z"}

虽然我考虑的结果进行解码，

pdtoption = ActiveSupport::JSON.decode(getcustomoptions(option.id)) 
debug pdtoption

是

{"id"=>3, "product_id"=>10647391438, "front_preview"=>"tomrain.s3.eu-central-1.amazonaws.com/productoptions/front_previews/000/000/003/original/collar-green-front.png?1496132797", "left_side_preview"=>"tomrain.s3.eu-central-1.amazonaws.com/productoptions/left_side_previews/000/000/003/original/t-shirt-left-side.jpg?1496132798", "back_preview"=>"tomrain.s3.eu-central-1.amazonaws.com/productoptions/back_previews/000/000/003/original/collar-green-back.png?1496132798", "right_side_preview"=>"tomrain.s3.eu-central-1.amazonaws.com/productoptions/right_side_previews/000/000/003/original/tshirt-brightlights-side.jpg?1496132798", "front_preview_file_name"=>"collar-green-front.png", "front_preview_content_type"=>"image/png", "front_preview_file_size"=>275338, "front_preview_updated_at"=>"2017-05-30T08:26:37.864Z", "left_side_preview_file_name"=>"t-shirt-left-side.jpg", "left_side_preview_content_type"=>"image/jpeg", "left_side_preview_file_size"=>79742, "left_side_preview_updated_at"=>"2017-05-30T08:26:38.280Z", "back_preview_file_name"=>"collar-green-back.png", "back_preview_content_type"=>"image/png", "back_preview_file_size"=>250070, "back_preview_updated_at"=>"2017-05-30T08:26:38.437Z", "right_side_preview_file_name"=>"tshirt-brightlights-side.jpg", "right_side_preview_content_type"=>"image/jpeg", "right_side_preview_file_size"=>56997, "right_side_preview_updated_at"=>"2017-05-30T08:26:38.618Z"}

但我无法打印/显示特定的值（例如：front_preview）。我为此奋斗了3个多小时，但找不到处理这种情况的正确方法。任何帮助/详细解释赞赏。

谢谢。

来源

2017-05-30 Ram Kumar

做'pdtoption ['front_preview']' –

你如何访问哈希值内？你可以发布视图的示例代码吗？ – Niklas

嗨，我的看法。我想这一点， 'code' <％ pdtoption = ::的ActiveSupport JSON.decode（getcustomoptions（option.id））％> <％= pdtoption [ 'front_view']％> 'code' 它引发ActionView :: Template :: Error（未定义方法'[]'为零：NilClass –

如果仔细查看ActiveSupport::Json.decode方法，它会解析您的Json字符串并返回Ruby Hash。要访问Hash pdtoption的数据，您需要使用普通的Ruby哈希访问器方法。

pdtoption["id"] #=> 3

要将数据从控制器传递到视图，您不需要每次对数据进行编码和解码。您可以将您的customoptions用您的帮助方法返回并在视图中进行访问。

来源

2017-05-30 11:37:46 Niklas

当我直接使用查询输出它似乎像这样， ---红宝石/对象：Productoption concise_attributes：？！ - 红宝石/对象：ActiveRecord的::属性:: FromDatabase 名称：ID value_before_type_cast：3 - 红宝石/对象：ActiveRecord的::属性:: FromDatabase 名称：PRODUCT_ID value_before_type_cast：10647391438 - 红宝石/对象：ActiveRecord的::属性:: FromDatabase 名：front_preview value_before_type_cast：collar-green-front.png 但找不到显示t的方法他列的价值。 –

如何访问RubyOnrails中的查询集合中的特定对象

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