如何格式化 Rails 编辑字段中显示的值? [英] How can I format the value shown in a Rails edit field?

问题描述

我想让编辑表单字段尽可能方便用户使用.例如，对于数值，我希望该字段以逗号显示(如 number_with_precision).

I would like to make editing form fields as user-friendly as possible. For example, for numeric values, I would like the field to be displayed with commas (like number_with_precision).

这在显示方面很容易，但是编辑呢?有什么好的办法吗?

This is easy enough on the display side, but what about editing? Is there a good way to do this?

我正在使用 Rails FormBuilder.经过调查，我发现它使用 InstanceTag，它通过使用 _value_before_type_cast 获取字段的值，这意味着不会调用覆盖 .

I am using the Rails FormBuilder. Upon investigation, I found that it uses InstanceTag, which gets the values for fields by using <attribute>_value_before_type_cast which means overriding <attribute> won't get called.

推荐答案

到目前为止，我想出的最好的东西是这样的:

The best I have come up with so far is something like this:

<%= f.text_field :my_attribute, :value => number_with_precision(f.object.my_attribute) %>

或者 my_attribute 可以返回格式化的值，像这样:

Or my_attribute could return the formatted value, like this:

def my_attribute
  ApplicationController.helpers.number_with_precision(read_attribute(:my_attribute))
end

但是你还是要使用:value

<%= f.text_field :my_attribute, :value => f.object.my_attribute %>

这看起来工作量很大.

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