sqlite math functions don't accept character fields as input

[Zachary Croker]

We have a view that performs some trig calculations. It works when testing in MySQL, but fails when using sqlite.

I have overridden the "RADIANS" function implementation from django in our conftest.py file. Details not that important, but essentially is this:

connection.create_function("RADIANS", 1, lambda x: math.radians(float(x)) if x is not None else None)

The issue is, there is a lat/lon field in our database, which is stored as a CharField (we can debate that decision later...), so when it gets passed into the _sqlite_radians function the test fails as it is invalid input. I think that these functions should be able to take in string values.

I have started a PR but thought before I submit it I should see if it is a 'genuine' bug or a decision not to support this field.

[Mariusz Felisiak]

Thanks for this ticket, however radians should not accept strings. You can cast values before passing them to this function.

[Zachary Croker]

Replying to Mariusz Felisiak:

Thanks for this ticket, however radians should not accept strings. You can cast values before passing them to this function.

Hi Mariusz, the sqlite docs specify that these functions should accept strings (see ​https://www.sqlite.org/lang_mathfunc.html)

"The arguments to math functions can be integers, floating-point numbers, or strings or blobs that look like integers or real numbers. If any argument is NULL or is a string or blob that is not readily converted into a number, then the function will return NULL."

Also - in this instance I am unable to cast the values because they are calculated wholly within the view (which I can't change)

[Mariusz Felisiak]

Replying to Zachary Croker:

Hi Mariusz, the sqlite docs specify that these functions should accept strings (see ​https://www.sqlite.org/lang_mathfunc.html)

We're trying to unify behavior for all backends. Accepting strings on SQLite may be confusing.

Please ​follow the triaging guidelines with regards to wontfix tickets and take this to DevelopersMailingList or the Django Forum, if you don't agree.