Ruby prasing csv date to format invalid date(argumentError) - ruby

Question

I am parsing a csv file and i need to change the dob to match a certain format of YYY-MM-DD I keep getting this error of parse': invalid date (ArgumentError)
it happens when it tries to parse this date of "6/6/99" How can i fix this so I don't get any errors for any of the dates I have?
list of all dates in csv, I am not sure if any of the other dates following the one above would error out as well.
"12/12/2010"
"1/1/1988"
"2/2/1966"
"6/6/99"
"1/4/88"
"4/4/1948"
"1/6/1988"
"1/7/1988"
"1/8/88"
"1/9/88"
"1988-02-12"
"1-11-88"
"1/12/88"
"1/13/88"
my code
require 'csv'
require 'time'
require 'date'
def parse_csv
table = CSV.parse(File.read("input.csv", encoding: 'bom|utf-8' ), headers: true, col_sep: ",")
formatted = table.map(&:to_h)
formatted.each do |x|
if x["dob"] =~ /^\d{4}-\d{2}-\d{2}$/
p "correct"
else
parsed = Date.parse(x["dob"], "%Y-%m-%d")
p parsed
end
end
end
parse_csv

Answer 1

From the documentation:
Date.parse
Parses the given representation of date and time, and creates a date
object.
This method does not function as a validator. If the input string
does not match valid formats strictly, you may get a cryptic result.
Should consider to use Date.strptime instead of this method as
possible.
Your current implementation doesn't really make sense; it's not doing what you think it is:
Date.parse('6/6/99', "%Y-%m-%d")
#=> Date::Error: invalid date
This isn't saying "convert "6/6/99" into "1999-06-06", it's saying "try to parse "6/6/99" into a Date object (and the second argument is essentially being ignored!).
If you're confident what format that date is supposed to be, then (as per the documentation referenced above!) you can use Date.strptime to try explicitly parsing it as this format. For example:
Date.strptime('6/6/99', "%m/%d/%y")
#=> #<Date: 1999-06-06 ((2451336j,0s,0n),+0s,2299161j)>
Or if you're not confident whether the first two values are supposed to represent month-day or day-month, then you'd need to handle this explicitly in the code and treat the error appropriately.
tl;dr:
Date.parse is unreliable for arbitrary inputs; it only makes a "best guess" for the date format. And unsurprisingly here, it fails for at least one of the ambiguous formats you're throwing at it.
Date.strptime is the correct way to parse each date, when you know which format you expect.