Newbie question

[Williams, Chris]

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Hi all,
I'm developing a rails web app here at work and I keep running into
a common thing in terms of setting instance variables with the property of a
form's parameter value. Basically I want the variable to take the
parameter's value if it exists, and to otherwise use a reasonable default.

I keep writing code like this:
if @params["limit"]
@limit = @params["limit"]
else
@limit = 50
end

if @params["chain"]
chain = @params["chain"]
else
chain = 1
end

Can someone please point me to a simpler, more succinct "ruby" way of doing
this?

Thanks,
Chris

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[Francis Hwang]

@limit = @params["limit"] || 50

Hi all,
I'm developing a rails web app here at work and I keep running into
a common thing in terms of setting instance variables with the
property of a
form's parameter value. Basically I want the variable to take the
parameter's value if it exists, and to otherwise use a reasonable
default.

I keep writing code like this:
if @params["limit"]
@limit = @params["limit"]
else
@limit = 50
end

if @params["chain"]
chain = @params["chain"]
else
chain = 1
end

Can someone please point me to a simpler, more succinct "ruby" way of
doing
this?

Thanks,
Chris

Francis Hwang
http://fhwang.net/

 

[Florian Gross]

I keep writing code like this:
if @params["limit"]
@limit = @params["limit"]
else
@limit = 50
end

if @params["chain"]
chain = @params["chain"]
else
chain = 1
end

I'd do something like this

defaults = {
"limit" => 50,
"chain" => 1
# more defaults
}
@values = defaults.merge(@params)

And then do @values["limit"] instead of @limit. This however only makes
sense when there is a logical connection between those values. I'd
prefer it in that case because it is way less duplication.