CODEWITHSUNDEEP
ruby-on-railsruby
Joe
Joe

Reputation: 795

Ruby - I need to convert string into a timestamp

I need to convert a string that represents a date to a timestamp object in Ruby.

For example:

   date_string = "18-Feb-2016 09:01:04"

   convert to a timestamp like so

   2016-02-18 14:01:04

I need to save this to a mysql database were the column is type timestamp.

I have researched this for most of the day and can not find a solution. I know you can use Time.parse but that includes timezone and DateTime.parse().to_time includes the timezone. Since it has to be a timestamp i can not use strftime method.

I need the time to be included because it will be used for calculation purposes.

Any help would be greatly appreciated.

Thank you

Upvotes: 3

Views: 14490

Answers (4)

Albert Paul
Albert Paul

Reputation: 1208

Use to_datetime method in Rails.

"12-10-2015".to_datetime

=> Mon, 12 Oct 2015 10:36:00 +0000

http://apidock.com/rails/String/to_datetime

Edited to add precise answer.

Upvotes: 2

Cary Swoveland
Cary Swoveland

Reputation: 110665

I've interpreted the question to be that you wish to convert the string "18-Feb-2016 09:01:04" to the string "2016-02-18 14:01:04" (generalized to arbitrary date-time strings, of course).

Let:

str = "18-Feb-2016 09:01:04"

What you want is done in two steps. The first is to convert this string to a DateTime object, that is, an instance of the class DateTime. The second step is to construct the desired string from the DateTime object.

One way to create the DateTime object is to use the method DateTime::parse:

require 'date'

DateTime.parse(str)
  #=> #<DateTime: 2016-02-18T09:01:04+00:00 ((2457437j,32464s,0n),+0s,2299161j)>

That works fine for the string format you gave, but can be problematic with other formats. For example:

DateTime.parse "4-5-16 09:01:04"
  #=> #<DateTime: 2004-05-16T09:01:04+00:00 ((2453142j,32464s,0n),+0s,2299161j)>

As long as you know the format that will be used, it's generally better to use DateTime#strptime with the appropriate pattern comprised of format directives:

pattern = "%d-%m-%y %H:%M:%S"
DateTime.strptime("4-5-16 09:01:04", pattern)
  #=> #<DateTime: 2016-05-04T09:01:04+00:00((2457513j,32464s,0n),+0s,2299161j)>

See DateTime#strftime for the format directives.

For the problem at hand:

dt = DateTime.strptime(str, "%d-%b-%Y %H:%M:%S")
  #=> #<DateTime: 2016-02-18T09:01:04+00:00 ((2457437j,32464s,0n),+0s,2299161j)>

The second step is to construct the desired string with the above-referenced strftime method:

dt.strftime("%Y-%m-%d %H:%M:%S")
  #=> "2016-02-18 09:01:04"

Upvotes: 1

Andrew Hendrie
Andrew Hendrie

Reputation: 6415

TL;DR 

datetime = DateTime.parse("18-Feb-2016 09:01:04").to_s(:db)

returns 

"2016-02-18 09:01:04"

Here's a quick explanation...

1. Convert your string to a Date object with DateTime.parse

You can use the .parse method from the Date or DateTime class in order to parse a string. The parse method will return a Date object like this:

$ DateTime.parse("18-Feb-2016 09:01:04")
$ => #<DateTime: 2016-02-18T09:01:04+00:00 ((2457437j,32464s,0n),+0s,2299161j)>

.parse is a method provided by Ruby.

2. Format the string with DateTime.parse.to_s

Ruby on Rails gives you access to the DateTime.to_formatted_s method to change the formatting of the Date object prior to storing it in your database.

To match the format that you specified:

$ datetime = DateTime.parse("18-Feb-2016 09:01:04").to_formatted_s

Note: to_s is aliased from to_formatted_s and to_formatted_s is a method provided by Rails, not Ruby.

Upvotes: 6

Amit Sharma
Amit Sharma

Reputation: 3477

You can use .to_time or .to_datetime, the .to_time returns the date and time with timezone but the .to_datetime returns full date with week name but it shows +0000 as timezone, you will see the difference in both the formats, see the following example.

# used .to_time

"18-Feb-2016 09:01:04".to_time
## Output
2016-02-18 09:01:04 +0530

# used .to_datetime

"18-Feb-2016 09:01:04".to_datetime
## Output
Thu, 18 Feb 2016 09:01:04 +0000

Upvotes: 1

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