Ruby Loop through some attributes of an object

Question

In Rails, I have a class name User, in which I just want to look at :name, :address, :age

I would like to write a piece of code that's something like:

user = User.new
[name, address, age].zip(["Name", "Address", 10]).each do |attribute, val|
  user.attribute = val
end

The thing is I don't know how to do it properly, since user.attribute is obviously not a valid line. In other word, is there anyway so that user.attribute gets evaluated as user.name, user.address, user.age depends on the loop?

Sergio Tulentsev · Accepted Answer · 2012-07-12 19:20:16Z

5

You should use send method

user.send "#{attribute}=", val

If attribute is, say, :name, then the line above is equivalent to

user.name = val

answered Jul 12, 2012 at 19:20

Sergio Tulentsev

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3 Comments

tokland Over a year ago

I'd use send as last resort, Rails provides write_attribute(attribute, value).

Sergio Tulentsev Over a year ago

Oh yes, he did actually mention rails. Just not in the tags :)

tokland Over a year ago

check again :-p. It's ok to show send as the basic metaprogramming method, but given that the OP is using rails we can mention both (and another way in my answer).

u19964 · Accepted Answer · 2012-07-12 20:14:13Z

1

Actually I can do it this way:

[name, address, age].zip(["Name", "Address", 10]).each do |attribute, val|
    user[attribute] = val
end

This way works, too

edited Jul 12, 2012 at 20:14

answered Jul 12, 2012 at 19:20

u19964

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Comments

tokland · Accepted Answer · 2012-07-12 20:20:04Z

1

user.send(:name) would be the same as calling user.name, so you may want to try that.

edited Jul 12, 2012 at 20:20

tokland

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answered Jul 12, 2012 at 19:21

nickgroenke

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Comments

tokland · Accepted Answer · 2012-07-13 18:06:20Z

1

user = User.new
[name, address, age].zip(["Name", "Address", 10]).each do |attribute, val|
  user.write_attribute(attribute, val)
end

But that's what I'd write:

user = User.new
user.attributes = {name => "Name", address => "Address", age => 10}

edited Jul 13, 2012 at 18:06

answered Jul 12, 2012 at 20:12

tokland

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