I just recently came across Andy Croll's article about using
strftime to format date and time values in a Rails View.
He makes a strong argument that you shouldn't use
strftime in a Rails View:
<%= @user.last_sign_in_at.strftime('%m-%e-%y %H:%M') %>
Because Rails has built in date and time formats, and you can also define your own. To use one of the built in formats you can just call
to_s on a
Time class and pass in the format you wish to use:
<%= @user.last_sign_in_at.to_s(:long) %>
See Andy Croll's article for the nitty gritty details.
If you've spent much time writing Ruby or Rails code you probably already see an issue with the
to_s call above. What if the
last_sign_in_at value is
You might think... "Hmm, no problem. Calling
nil just returns an empty string, so no harm, no foul."
nil.to_s => ""
Well, there are two problems with that line of thinking. First, Rails actually creates a
to_formatted_s method that takes a single argument which references the format to use. The
to_formatted_s method is aliased too
Time objects. If you try to pass an argument to
nils version of
to_s you get an error.
nil.to_s(:long) ArgumentError (wrong number of arguments (given 1, expected 0))
Second, you might actually want to have some visual representation that the date or time is missing or unset. I like to show a couple of dash characters when a date or time is missing.
Best of Both Worlds
Here is how I handle date and time formatting in my Rails apps.
application_helper module I add a
format_date method, so it is available to every view.
def format_date(date, format = :long) date.blank? ? '--' : date.to_s(format) end
In your views you can call it like so:
<%= format_date @user.last_sign_in_at %>
If the user has never signed in you will see the two dashes that signify there is no
last_sign_in_at time set. Otherwise the
last_sign_in_at will be formatted with the
If you want to override the default format you can always pass in a different one.
<%= format_date @user.last_sign_in_at, :db %>
Or use your own format (provided you defined one as outlined in Andy Croll's article).
<%= format_date @user.last_sign_in_at, :myformat %>
Be aware of
nils in your code. Anytime you see a
. in your code think to yourself, "What happens if the thing on the left side of that
Originally posted at davidlains.com.
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