Ruby on Rails

On 20 September 2013 08:30, Fai Wong <wong...@gmail.com> wrote:
> If I store 1.month as a string in the database, how do I convert "1.month"
> into 1.month?
>
> This way I can use the "1.month" value stored in database to perform the
> following calculation.
>
> Time.now + 1.month

If you really feel you need to do this then you can store "1.month" as
a string and use eval

1.9.3p194 :007 > delta = "1.month"
 => "1.month"
1.9.3p194 :008 > Time.now
 => 2013-09-22 08:52:13 +0100
1.9.3p194 :009 > Time.now + eval( delta )
 => 2013-10-22 08:52:23 +0100

However if you do this be /very/ careful about what can get into the
database as arbitrary code can be executed using eval and conceivably
your machine could be hacked.  I DO NOT recommend that you do this.
If your requirement is for a delta with values such as 1 month 3 weeks
and so on, then I suggest having two fields, one for the quantity and
an enumerated value for the period (month, week and so on).  Then work
it out in code.  Less efficient but /much/ safer.

Colin

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