Question

In rails we can access db column through attributes rails provided, but can we change this ?
for example I have db with name column could I implement something like.

def name
  "sir" + name
end

I tried it, but it result in stack overflow. There is a way to accomplish this.

more question, Is there any difference between name and self.name.

Answer 1

def name
  "sir" + read_attribute(:name)
end

But avoid this practice. Use an additional getter/setter instead, also known as “virtual attribute”.
For more information read this answer: decorating an attribute in rails

In your case, there’s also a weird side effect. Each time the attribute is accessed, it appends the name. After 3 calls, you end up with

"sir sir sir name"

Indeed, you can do

def name
  n = read_attribute(:name)
  if /^sir/.match(name)
    n
  else
    "sir #{n}"
  end
end

but, seriously, don’t do this.