The Rails Style Guide recommends using self[:attr]
over read_attribute(:attr)
.
You can use it like this:
def name
name_trans || self[:name]
end
質問
I'm trying to overwrite a getter method for an ActiveRecord model. I have an attribute called name
in the model Category
, and I'd like to be able to do something like this:
def name
name_trans || name
end
If name_trans
attribute is not nil, then return it, else return name
attribute. How would I do this?
This should then be called normally like this:
@category.name
解決
The Rails Style Guide recommends using self[:attr]
over read_attribute(:attr)
.
You can use it like this:
def name
name_trans || self[:name]
end
他のヒント
Update: The preferred method according to the Rails Style Guide is to use self[:name]
instead of read_attribute
and write_attribute
. I would encourage you to skip my answer and instead prefer this one.
You can do it exactly like that, except that you need to use read_attribute
to actually fetch the value of the name attribute and avoid the recursive call to the name
method:
def name
name_trans || read_attribute(:name)
end
I would like to add another option for overwriting getter method, which is simply :super.
def name
name_trans || super
end
this works not just on attributes getter method, but also associations getter methods, too。
Overriding the getter and using read_attribute
does not work for associations, but you can use alias_method_chain
instead.
def name_with_override
name_trans || name_without_override
end
alias_method_chain :name, :override
If you using store attributes like this
store :settings, accessors: [:volume_adjustment]
or
using gems like
hstore_accessor
gem link
So you ended up using store
method on model, then to override those method you can't use self.read_attribute
, you must use instead super
like that:
def partner_percentage
super.to_i || 10
end
If someone want update the value after name_trans
in getter method, you could use self[:name]=.
def name
self[:name] = name_trans || self[:name]
# don't do this, it will cause endless loop
# update(name: name_trans)
end
You can use Rails read_attribute method. Rails docs