Rails 3：呈现 JSON 中对象数组的某些属性
在我看来，我正在尝试将一些数据传递给javascript。我只想要数组中对象的某些属性。
json gem 似乎不支持 :only 选项。我尝试使用 ActiveSupport::JSON
<script>
test1=<%=raw ActiveSupport::JSON.encode(@sectionDatas.values, :only => [ :left, :width ])%>;
</script>
但忽略 :only 并打印整个对象。
然后我想我会很聪明，从控制器中获取 render 方法：
test2=<%=raw render :json => @sections.as_json(:only => [:left, :width])%>
但我得到了 Nil:Nilclass 错误。
我还尝试将其放入我的模型中并运行 to_json:
include ActiveModel::Serialization::JSON
def attributes
@attributes ||= {'left' => 0, 'width'=>0}
end
同样，这会忽略属性方法并序列化整个对象。
当然，这一定很简单。我缺少什么？
I'm trying to pass some data to javascript in my view. I only want certain attributes of the objects in the array.
The json gem doesn't appear to support the :only option. I tried to use ActiveSupport::JSON
<script>
test1=<%=raw ActiveSupport::JSON.encode(@sectionDatas.values, :only => [ :left, :width ])%>;
</script>
but that ignores the :only and prints the whole object.
Then I thought I would be clever and take the render method from the controller:
test2=<%=raw render :json => @sections.as_json(:only => [:left, :width])%>
but I get Nil:Nilclass errors.
I also tried to put this in my model and run to_json:
include ActiveModel::Serialization::JSON
def attributes
@attributes ||= {'left' => 0, 'width'=>0}
end
Again, this ignores the attributes method and serializes the whole object.
Surely this must be simple. What am I missing?
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假设数组中的对象是
ActiveRecord::Base的实例或包含ActiveModel::Serialization::JSON：Assuming the objects in the array are instances of
ActiveRecord::Baseor includeActiveModel::Serialization::JSON:当您使用
select从数据库获取对象时，您可以过滤掉不需要的列。当然，这不是Rails3的方式。这里是：
更新
如果您想要原始的对象数组和 json 但带有过滤属性的 json，您将需要覆盖 to_json：
此 帖子解释了如何做到这一点：
如何在Rails中覆盖to_json？
You can filter out the columns you don't need when you get objects from the db with
select.Of course, this is not the Rails3 way. Here that is:
Update
If you want to have the original array of objects and json but the json with filtered attributes you will need to override to_json:
This post explains how to do that:
How to override to_json in Rails?