Date Validator

• To query the weather in a particular date, user need to input two parameters: location and date.

For date parameter, I need to check if the date value and format is valid.

• Check the Value

  1. For the free version, Open Weather Map Daily API provides 16 days forecast.

  2. Thinkpage Daily API only provides 3 days(including today).

     So here, I'll set the valid date from today to today+2

  3. Use timedelta() to get the duration

     date.today() <= date <= date.today()+timedelta(days=2)
     

• Convert the input date string to date object in a particular Format: %Y-%m-%d

  1. datetime.strptime(date_string, format) creates a datetime object from a string representing a date and time.
  2. datetime.date() converts datetime object to date object.

  3. If the input date string is not in '%Y-%m-%d ' format, it will raise a ValueError exception.

     try:
      date = datetime.strptime(date, '%Y-%m-%d').date()
     except ValueError:
      print('输入错误，时间格式为yyyy-mm-dd，请重新输入.')
     

So the entire function is as below:

from datetime import date
from datetime import timedelta
from datetime import datetime


def date_validator(date):
    '''validate the input date value and format'''
    try:
        date = datetime.strptime(date, '%Y-%m-%d').date()
    except ValueError:
        print('输入错误，时间格式为yyyy-mm-dd，请重新输入.')
        return False
    else:
        if date.today() <= date <= date.today()+timedelta(days=2):
            return True
        else:
            print('日期超出范围，仅可查询3日内天气预报，请重新输入!')
            return False