How to use a variable as object attribute in rails?

Question

I have a PaymentDetail model with attribute 'home_address_country', so i can use

    @payment_detail.home_address_country //where @payment_detail is object of that model.

I want to use something like this:---

country_attribute=address_type+"_address_country"  //where address type is equal to 'home'
 @payment_detail."#{country_attribute}"

Means attribute name is stored in a variable. How can i do this?

EDIT

country_attribute=address_type+"_address_country"
country_list=Carmen::country_names
eval("@#{country_attribute} = #{country_list}")

Harish Shetty · Accepted Answer · 2012-06-26 20:01:10Z

43

Reading AR attribute

@payment_detail.send("#{address_type}_address_country")

OR

@payment_detail.read_attribute("#{address_type}_address_country")

Writing AR attribute

@payment_detail.send("#{address_type}_address_country=", value)

OR

@payment_detail.write_attribute("#{address_type}_address_country", value)

Setting instance variable

@payment_detail.instance_variable_set("@#{address_type}_address_country", value)

Getting instance variable

@payment_detail.instance_variable_get("@#{address_type}_address_country")

Reference

send method documentation
read_attribute method documentation
write_attribute method documentation
instance_variable_get method documentation
instance_variable_set method documentation

edited Jun 26, 2012 at 20:01

answered Oct 12, 2010 at 10:56

Harish Shetty

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Comments

Denis Malinovsky · Accepted Answer · 2013-07-19 04:58:32Z

4

Recommended way for Rails 3 is to use dictionary-like access:

attr = @payment_detail["#{address_type}_address_country"]
attr = "new value"
@payment_detail["#{address_type}_address_country"] = attr

read_attribute and write_attribute methods work for Rails 2 only.

answered Jul 19, 2013 at 4:58

Denis Malinovsky

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1 Comment

Dylan Over a year ago

FYI, I'm testing this in Rails 4 and #read_attribute is still operational -- not sure about #write_attribute. I'm switching to use #send instead, though.

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