CODEWITHSUNDEEP
ruby-on-railsrubydatetime
Aurimas
Aurimas

Reputation: 2717

How to check if variable is Date or Time or DateTime in Ruby?

Any easy way to check if a variable / object is of Date / Time / DateTime type? Without naming all the types

Upvotes: 22

Views: 24251

Answers (9)

Lief
Lief

Reputation: 593

In Rails you can use the acts_like? method. Time does not act_like_date? so you need to check for date and time.

var.acts_like?(:date) || var.acts_like?(:time)

Upvotes: 3

CamiloVA
CamiloVA

Reputation: 731

In rails 5.2+ you can test if an object is_a?

Date.today.is_a?(Date) # -> true
Date.today.is_a?(DateTime) # -> false

Upvotes: 4

zeke
zeke

Reputation: 3663

Another option:

def is_datetime(d)
  d.methods.include? :strftime
end

Or alternatively:

if d.respond_to?(:strftime)
  # d is a Date or DateTime object
end

Upvotes: 35

Tímor Espallargas
Tímor Espallargas

Reputation: 9

For the sake of completion, another option would be:

def responds_to_datetime?(date)
  true if date.to_datetime rescue false
end

Upvotes: 0

wuyuedefeng
wuyuedefeng

Reputation: 61

The Column objects returned by columns and columns_hash can then be used to get information such as the data type and default values, for example:

User.columns_hash['email'].type
=> :string
User.columns_hash['email'].default
=> nil
User.columns_hash['email'].sql_type
=> "varchar(255)"

(Source)

Upvotes: 1

13aal
13aal

Reputation: 1674

To find what class the module (or method) is located in, you use the .class function, this allows you to inspect Ruby objects to find out what class they are located in. The syntax for this looks like this: object.class. Here's some examples:

irb(main):001:0> require 'date'
=> true
irb(main):002:0> d = Date.today
=> #<Date: 2016-06-22 ((2457562j,0s,0n),+0s,2299161j)>
irb(main):003:0> t = Time.now
=> 2016-06-22 18:52:24 -0500
irb(main):004:0> t.class
=> Time
irb(main):005:0> d.class
=> Date

As you can see this is an easy and simple way to find the class that the object is in.

Upvotes: 1

Ronan Lopes
Ronan Lopes

Reputation: 3398

you can inspect the class of a object doing

object.class

It should return Date, String or whatever it is. You can also do the reverse and check if an object is an instance of a class:

object.instance_of?(class)

where class is the one you want to check (String, Date), returning true/false

Upvotes: 6

robert.otherone
robert.otherone

Reputation: 48

I do not think there is an "easy way" without typing all the type variations of Date / Time / DateTime / Timezone out.

The simplest and fastest way is to do dateTime.is_a?(DateTime) or Time.is_a?(Time), repeat ad nausem - which all will return a boolean.

Conversely you can also use kind_of?.

You might also be able to find a framework that has a function to check all of the variations of date and time.

Upvotes: 1

nisevi
nisevi

Reputation: 626

If you want to verify the object, here you have a couple of examples:

nisevi@nisevi ~:$ irb
irb(main):001:0> require "date"
=> true
irb(main):002:0> require "time"
=> true
irb(main):003:0> d = Date.new
=> #<Date: -4712-01-01 ((0j,0s,0n),+0s,2299161j)>
irb(main):004:0> dt = DateTime.new
=> #<DateTime: -4712-01-01T00:00:00+00:00 ((0j,0s,0n),+0s,2299161j)>  
irb(main):005:0> t = Time.new
=> 2016-06-22 21:33:09 +0200

irb(main):014:0> d.instance_of?(Date)
=> true
irb(main):015:0> d.instance_of?(DateTime)
=> false
irb(main):016:0> d.instance_of?(Time)
=> false
irb(main):017:0> dt.instance_of?(DateTime)
=> true
irb(main):018:0> dt.instance_of?(Time)
=> false
irb(main):019:0> dt.instance_of?(Date)
=> false
irb(main):020:0> t.instance_of?(Time)
=> true
irb(main):021:0> t.instance_of?(DateTime)
=> false
irb(main):022:0> t.instance_of?(Date)
=> false

Also I think that TimeZone is from Rails and not from Ruby.

As per your comment if you want to convert a Time object to DateTime I think that something like this it should work:

def time_to_datetime time
  return time.to_datetime if time.instance_of?(Time)
  false
end

Here you have some code:

irb(main):026:0> t.instance_of?(Time)
=> true
irb(main):027:0> t.methods.sort.to_s
=> "[:!, :!=, :!~, :+, :-, :<, :<=, :<=>, :==, :===, :=~, :>, :>=, :__id__, :__send__, :asctime, :between?, :class, :clone, :ctime, :day, :define_singleton_method, :display, :dst?, :dup, :enum_for, :eql?, :equal?, :extend, :freeze, :friday?, :frozen?, :getgm, :getlocal, :getutc, :gmt?, :gmt_offset, :gmtime, :gmtoff, :hash, :hour, :httpdate, :inspect, :instance_eval, :instance_exec, :instance_of?, :instance_variable_defined?, :instance_variable_get, :instance_variable_set, :instance_variables, :is_a?, :isdst, :iso8601, :itself, :kind_of?, :localtime, :mday, :method, :methods, :min, :mon, :monday?, :month, :nil?, :nsec, :object_id, :private_methods, :protected_methods, :public_method, :public_methods, :public_send, :remove_instance_variable, :respond_to?, :rfc2822, :rfc822, :round, :saturday?, :sec, :send, :singleton_class, :singleton_method, :singleton_methods, :strftime, :subsec, :succ, :sunday?, :taint, :tainted?, :tap, :thursday?, :to_a, :to_date, :to_datetime, :to_enum, :to_f, :to_i, :to_r, :to_s, :to_time, :trust, :tuesday?, :tv_nsec, :tv_sec, :tv_usec, :untaint, :untrust, :untrusted?, :usec, :utc, :utc?, :utc_offset, :wday, :wednesday?, :xmlschema, :yday, :year, :zone]"
irb(main):028:0> t.to_datetime
=> #<DateTime: 2016-06-22T21:33:09+02:00 ((2457562j,70389s,767750206n),+7200s,2299161j)>
irb(main):029:0> t.instance_of?(Time)
=> true
irb(main):030:0> t.instance_of?(DateTime)
=> false
irb(main):031:0> tdt = t.to_datetime
=> #<DateTime: 2016-06-22T21:33:09+02:00 ((2457562j,70389s,767750206n),+7200s,2299161j)>
irb(main):032:0> tdt.instance_of?(Time)
=> false
irb(main):033:0> tdt.instance_of?(DateTime)
=> true

Here you have some interesting info In Ruby on Rails, what's the difference between DateTime, Timestamp, Time and Date?

Upvotes: 5

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