Check If Date is Valid in Python

This tutorial will discuss about a unique way to check if date is valid in Python.

Suppose we have a date in this string format like this,

dateStr1 = '2023-04-24'

We want to check if it is a valid date or not. By valid we mean that this date actually exist. Suppose if someone give us a date like 2023-02-30 i.e. 30th february, it does not exist or suppose 45th March, that too does not exist. So we need to check if a given date is valid or not.

We have created a method for this,

from datetime import datetime

def is_valid(dateStr):
    # Checks if a given date string is a valid date.
    # Returns True, if date string is valid, False otherwise.
    result = True
    try:
        datetime.strptime(dateStr, '%Y-%m-%d')
    except ValueError:
        result = False
    return result

It accepts a date in the string format and check sif the given date string is valid or not. It returns True, if the give date string is valid, otherwise it returns false.

Inside the method, we will convert the date in string format to datetime object using the strptime() method. In which, we will pass the date string as first argument and the format in which date is stored in the string as a second argument. If it is a valid date, then strptime() will return a datetime object, but if it is not a valid date did then strptime() method will raise the value error.

We can catch this exception to check if the given date is valid or not. In the below example, we can use the this method to check if we given date string is valid or not.

Let’s see the complete example,

from datetime import datetime

def is_valid(dateStr):
    # Checks if a given date string is a valid date.
    # Returns True, if date string is valid, False otherwise.
    result = True
    try:
        datetime.strptime(dateStr, '%Y-%m-%d')
    except ValueError:
        result = False
    return result

## Example 1

dateStr1 = '2023-04-24'

# Check if dateStr1 is a Valid date
if is_valid(dateStr1):
    print('Yes, Date is Valid')
else:
    print('No, Date is not Valid')

## Example 2

dateStr2 = '2023-02-31'

# Check if dateStr2 is a Valid date
if is_valid(dateStr2):
    print('Yes, Date is Valid')
else:
    print('No, Date is not Valid')

Output

Yes, Date is Valid
No, Date is not Valid

Summary

We learned about a way to check if a date is valid or not in Python.