Forum: Ruby on Rails Date Comparison Problems

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Charley M. (Guest)
on 2008-11-24 18:35
I'm trying to compare two dates (one from a database, and the other is
the current date).  Here is the code I'm using:

------
    if document.nil?
      "doc_none"
    elsif document.status == 'archived'
      "doc_archived"
    elsif document.expiration_on < 720.days.ago
      "doc_expired_720"
    elsif document.expiration_on < 360.days.ago
      "doc_expired_360"
    elsif document.expiration_on < 90.days.ago
      "doc_expired_90"
    elsif document.expiration_on < 60.days.ago
      "doc_expired_60"
    elsif document.expiration_on < 30.days.ago
      "doc_expired_30"
    elsif document.expiration_on < 0.days.ago
      "doc_expired"
    elsif document.expiration_on < 30.days.from.now
     "doc_expiring_30"
    elsif document.expiration_on < 60.days.from.now
      "doc_expiring_60"
    else
      "doc_current"
    end
------

Here is the error in my log:

------
ActionView::TemplateError (comparison of Date with Time failed) on line
#46 of app/views/admin/documents/list.rhtml:
43:   <tr>
44:             <td><%= link_to
document.expiration_on.strftime("%Y.%m.%d"), :action => 'show', :id =>
document %></td>
45:             <td><%= link_to_organization(document.organization)
%></td>
46:             <td class="<%= expiration_class(document) %>">
47:                                     <%=hh document.status_readable
%> </td>
48:             <td><%= link_to_doctype(document.doctype) %></td>
49:         <td><%= link_to document.service_date.strftime("%Y.%m.%d"),
:action => 'show', :id => document %></td>

    #{RAILS_ROOT}/app/helpers/organizations_helper.rb:12:in `<'
    #{RAILS_ROOT}/app/helpers/organizations_helper.rb:12:in
`expiration_class'
    #{RAILS_ROOT}/app/views/admin/documents/list.rhtml:46
    #{RAILS_ROOT}/app/views/admin/documents/list.rhtml:42:in `each'
    #{RAILS_ROOT}/app/views/admin/documents/list.rhtml:42
------

It sounds like my dates aren't in the same format, but I'm not sure what
the solution is.  I'm using mySQL, and the field that I'm grabbing the
data from is of type "date".
Frederick C. (Guest)
on 2008-11-24 19:40
(Received via mailing list)
On 24 Nov 2008, at 16:35, Charley M. wrote:

>      "doc_expired_720"
>    elsif document.expiration_on < 30.days.from.now
>     "doc_expiring_30"
>    elsif document.expiration_on < 60.days.from.now
>      "doc_expiring_60"
>    else
>      "doc_current"
>    end
> ------
>
So ruby has several classes to do with dates and times.
- Time which is implemented as a number of seconds since an epoch
(usually a 32bit which restricts the range of representable dates)
- Date which is a number of days (with all the niceties to do with
Julian reform, Gregorian reform etc...)
- DateTime which is sort of like Date but which also has time of day
info

date columns on the database comes back as instances of Date, but
0.days.ago etc.. will be instances of Time.
You can convert these around with to_date/to_s.

I might write this as
delta = Date.today - document.expiration_on
case delta
when 720..360 then 'doc_expired_360'
when 360..90 then 'doc_expired_90'

etc...

Fred
Charley M. (Guest)
on 2008-11-24 20:40
I've written it as this:

----
  def expiration_class(document)

    delta = Date.today - document.expiration_on

    result = case delta
        when 720..360: "doc_expired_360"
        when 360..90:  "doc_expired_90"
        when 90..60:   "doc_expired_60"
        when 60..30:   "doc_expired_30"
        when 30..1:    "doc_expired"
        else 'doc_current'
    end

  end
end
----

The problem, though, is that it's returning all deltas as "doc_current",
when I know they're not.  Any ideas?


Frederick C. wrote:
> I might write this as
> delta = Date.today - document.expiration_on
> case delta
> when 720..360 then 'doc_expired_360'
> when 360..90 then 'doc_expired_90'
>
> etc...
>
> Fred
Frederick C. (Guest)
on 2008-11-24 20:47
(Received via mailing list)
On 24 Nov 2008, at 18:40, Charley M. wrote:

>        when 360..90:  "doc_expired_90"
> The problem, though, is that it's returning all deltas as
> "doc_current",
> when I know they're not.  Any ideas?
>
because your ranges are back to front. ranges must be
smallest..largest (check whether you want ... instead of .. i never
remember which is which)

Fred
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