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Never write your own date parsing library
11–20 of 333 posts
Re: Never write your own date parsing library
#12It's like that joke someone posted on Twitter: "I was in favor of space exploration until I realized what it would mean for date/time libraries"
Re: Never write your own date parsing library
#13I ran into date heck recently in a medical setting for storing birthdates. Eventually I settled on the idea that a birthdate isn’t a physical time, it’s just a string. We can force the user to enter it in the format 02/18/1993 leading zeroes and all, and operations on it other than string equality are invalid. We’ll see if this survives contact with the enemy but it’s already going better than storing and reasoning a…
Even better, just make the user input dates using a calendar date picker widget instead of a text field. This gives you full control of the input.
I've had to click back once per year old I am sometimes. I'd rather just type my birthday.
Re: Never write your own date parsing library
#14I ran into date heck recently in a medical setting for storing birthdates. Eventually I settled on the idea that a birthdate isn’t a physical time, it’s just a string. We can force the user to enter it in the format 02/18/1993 leading zeroes and all, and operations on it other than string equality are invalid. We’ll see if this survives contact with the enemy but it’s already going better than storing and reasoning a…
> in the format 02/18/1993 Is this DD/MM/YYYY or MM/DD/YYYY? I can tell from the 18 that it's the latter, but that convention isn't universal. I'd recommend YYYY/MM/DD as a less ambiguous format, but I don't have a perfect answer.
Furthermore, require dashes over slashes to signal that you are expecting ISO-8601 compatible dates, i.e., YYYY-MM-DD. Most users does not know the standard even exists, but it serves as an affordance that it is different from dd/mm/yyyy, etc.
Re: Never write your own date parsing library
#15Good general rule of thumb, but desperate scenarios call for desperate measures. I would never do this in Python or Rust for example, but it's necessary in Javascript; `Date` and `Moment`, are so full of traps that the ends justify the means: Especially if you have use for a `Date` or `Time` type.
Re: Never write your own date parsing library
#16I ran into date heck recently in a medical setting for storing birthdates. Eventually I settled on the idea that a birthdate isn’t a physical time, it’s just a string. We can force the user to enter it in the format 02/18/1993 leading zeroes and all, and operations on it other than string equality are invalid. We’ll see if this survives contact with the enemy but it’s already going better than storing and reasoning a…
I guess in your case you're never doing date arithmetic or greater than or less than, but only doing equality testing, right? That is, it's part of a composite key.
I faced a similar problem with a form where people were supposed to submit a date and probably not aware of what timezone was involved. I figured that so long as they selected "02/28/1993" and people always saw "02/28/1993" that was correct and if they ever saw it differently it was wrong. So I used non-TZ aware dates throughout the whole system.
Re: Never write your own date parsing library
#17Earlier quoted context omitted.
> in the format 02/18/1993 Is this DD/MM/YYYY or MM/DD/YYYY? I can tell from the 18 that it's the latter, but that convention isn't universal. I'd recommend YYYY/MM/DD as a less ambiguous format, but I don't have a perfect answer.
Furthermore, require dashes over slashes to signal that you are expecting ISO-8601 compatible dates, i.e., YYYY-MM-DD. Most users does not know the standard even exists, but it serves as an affordance that it is different from dd/mm/yyyy, etc.
Those ISO-8601 dates are great for date processing with primitive tools such as GNU sort or awk since they sort lexically, at least if you're not comparing dates in different time zones.
Re: Never write your own date parsing library
#18Good general rule of thumb, but desperate scenarios call for desperate measures. I would never do this in Python or Rust for example, but it's necessary in Javascript; `Date` and `Moment`, are so full of traps that the ends justify the means: Especially if you have use for a `Date` or `Time` type.
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Re: Never write your own date parsing library
#19On a slightly related note, here's an algorithm for parsing time from natural inputs into a normalized time:
Re: Never write your own date parsing library
#20Multiple times in my career I've had a good laugh when a non-technical manager says something along the lines of "it's just the date, how hard can it be?"
Add phone numbers, email addresses and human names to the list.