Better way to build string

[marcus]

I'm trying to build a query string based on an array of properties. Is
there a shorter/nicer way to do the following?

def build_query_string(properties, prop_type)
result = ""

properties.each do |item|
if prop_type == "tag"
result += " #{item.name}=#{item.value}"
else
if result == ""
result = "?"
else
result += "&"
end
result += "#{item.name}=#{item.value}"
end
end

result
end

/Marcus

[Peter Ertl]

I always find it useful to post code that is runnable
by copy+paste so people trying to help me don't have
to implement all the helper stuff first.

> --- Ursprüngliche Nachricht ---
> Von: marcus <m-l...@bristav.se>
> An: ruby...@ruby-lang.org (ruby-talk ML)
> Betreff: Better way to build string
> Datum: Wed, 9 Nov 2005 03:41:28 +0900

[Peter Ertl]

def build_query_string(properties, prop_type)
query = properties.map {|p| "#{p.name}=#{p.value}"}
case prop_type
when "tag": (" " + query.join(" "))
else ("?" + query.join("&"))
end
end

> --- Ursprüngliche Nachricht ---
> Von: marcus <m-l...@bristav.se>
> An: ruby...@ruby-lang.org (ruby-talk ML)
> Betreff: Better way to build string
> Datum: Wed, 9 Nov 2005 03:41:28 +0900
>

[Eero Saynatkari]

Perhaps you can modify this for your needs:

properties.inject('?') {|memo, (key, value)| memo << "#{key}=#{value}&" }

> /Marcus

E

[Eric Schwartz]

Eero Saynatkari <rub...@magical-cat.org> writes:
> Perhaps you can modify this for your needs:
>
> properties.inject('?') {|memo, (key, value)| memo << "#{key}=#{value}&" }

FWIW, I've had a mental block about inject for some time, and this
example very nicely clarified for me what it does and how. Thanks for
the handy example.

Note to OP: Don't forget to use CGI::escape() to properly URL-encode
everything.

-=Eric

[Eric Hodel]

"?" + properties.map { |pair| pair.join('=') }.join('&')

Shorter, more expressive, omits the trailing '&'

--
Eric Hodel - drb...@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E 7C11 332A 551C 796C 9F04

[Daniel Sheppard]

I'm guessing your code either includes name/value pairs for html/xml tag
attributes or for a query string. I don't see why those two things would
be put in the same function, but if you REALLY want them to spend their
lives together:

return "" if properties.empty?
if prop_type == "tag"
properties.map {|item| " #{item.name}=#{item.value}"}
#or alternatively:
#" " + properties.map {|item|
"#{item.name}=#{item.value}"}.join(" ")
else
"?" properties.map {|item| "#{item.name}=#{item.value}"}
end

If you're using this function for what I think you're using it for...
make sure you escape things properly. For the query strings, use:

require 'uri'
"?" + properties.map {|item| "#{item.name}=#{URI.escape(item.value)}"}

For the attributes, make sure that you escape the values to remove &,"
and ' and any other character that doesn't belong in your encoding. Even
better, use something like Builder if you're building up XML/XHTML.

> -----Original Message-----
> From: marcus [mailto:m-l...@bristav.se]
> Sent: Wednesday, 9 November 2005 5:41 AM
> To: ruby-talk ML
> Subject: Better way to build string
>
> I'm trying to build a query string based on an array of
> properties. Is there a shorter/nicer way to do the following?
>
> def build_query_string(properties, prop_type)
> result = ""
>
> properties.each do |item|
> if prop_type == "tag"
> result += " #{item.name}=#{item.value}"
> else
> if result == ""
> result = "?"
> else
> result += "&"
> end
> result += "#{item.name}=#{item.value}"
> end
> end
>
> result
> end
>

> /Marcus
>
>
>
>
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[marcus]

Thank you everyone. I went with this one as it was the only one who took
everything into account

Peter Ertl wrote:
> def build_query_string(properties, prop_type)
> query = properties.map {|p| "#{p.name}=#{p.value}"}
> case prop_type
> when "tag": (" " + query.join(" "))
> else ("?" + query.join("&"))
> end
> end

/Marcus