Обсуждение: Documentation 9.8. Data Type Formatting Functions: missing behaviour on invalid input at to_date()
Documentation 9.8. Data Type Formatting Functions: missing behaviour on invalid input at to_date()
От
PG Doc comments form
Дата:
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/12/functions-formatting.html Description: For the formatting functions, which convert between a string and a type like date, timestamp or number, there should be a description about the behaviour of i.e. to_date(input, mask) in case of invalid, not convertable input. I expected a return value of NULL and got a execution error.
On Fri, Jun 5, 2020 at 11:16:59AM +0000, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/12/functions-formatting.html > Description: > > For the formatting functions, which convert between a string and a type like > date, timestamp or number, there should be a description about the behaviour > of i.e. to_date(input, mask) in case of invalid, not convertable input. > > I expected a return value of NULL and got a execution error. Well, the value isn't "unknown", it is invalid, so an error seems appropriate. I don't remember anyone complaining the expected a NULL return. -- Bruce Momjian <bruce@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee
Re: Documentation 9.8. Data Type Formatting Functions: missingbehaviour on invalid input at to_date()
От
"David G. Johnston"
Дата:
On Fri, Jun 12, 2020 at 2:28 PM Bruce Momjian <bruce@momjian.us> wrote:
On Fri, Jun 5, 2020 at 11:16:59AM +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/12/functions-formatting.html
> Description:
>
> For the formatting functions, which convert between a string and a type like
> date, timestamp or number, there should be a description about the behaviour
> of i.e. to_date(input, mask) in case of invalid, not convertable input.
>
> I expected a return value of NULL and got a execution error.
Well, the value isn't "unknown", it is invalid, so an error seems
appropriate. I don't remember anyone complaining the expected a NULL
return.
The complaint is about us not explicitly documenting which of "error" or "null" is the outcome so the reader is left to assume or test it themselves. The OP isn't saying our choice is wrong, just our lack of documentation of said choice.
I believe the current reality is the user should assume that problems result in errors unless the function documents that it will return NULL.
David J.
On Fri, Jun 12, 2020 at 02:47:29PM -0700, David G. Johnston wrote: > On Fri, Jun 12, 2020 at 2:28 PM Bruce Momjian <bruce@momjian.us> wrote: > > On Fri, Jun 5, 2020 at 11:16:59AM +0000, PG Doc comments form wrote: > > The following documentation comment has been logged on the website: > > > > Page: https://www.postgresql.org/docs/12/functions-formatting.html > > Description: > > > > For the formatting functions, which convert between a string and a type > like > > date, timestamp or number, there should be a description about the > behaviour > > of i.e. to_date(input, mask) in case of invalid, not convertable input. > > > > I expected a return value of NULL and got a execution error. > > Well, the value isn't "unknown", it is invalid, so an error seems > appropriate. I don't remember anyone complaining the expected a NULL > return. > > > The complaint is about us not explicitly documenting which of "error" or "null" > is the outcome so the reader is left to assume or test it themselves. The OP > isn't saying our choice is wrong, just our lack of documentation of said > choice. > > I believe the current reality is the user should assume that problems result in > errors unless the function documents that it will return NULL. Yeah, it would be annoying to have to read that invalid input returns an error and not null in every place this happens. -- Bruce Momjian <bruce@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee