Hi Jody,
null is not particularly useful in most expressions, as a consequence I'm
not surprised there is not a NULL literal.
However, just like in SQL, there is a "IS NULL" operator. From our examples
<https://docs.geotools.org/latest/userguide/library/cql/ecql.html>:
Filter filter = ECQL.toFilter(" Name IS NULL");
What other "null" needs do you have?
Cheers
Andrea
On Fri, May 15, 2020 at 4:17 AM Jody Garnett <jody.garn...@gmail.com> wrote:
> I have been updating mbstyle filter to support expressions, and ran into
> something odd when writing tests (using ECQL to compare the output). It
> appears that a literal null value does not have a representation in ECQL.
> Indeed right now this causes a nice stacktrace to ECQL.toECQL( filter ).
>
> I am not sure how we made it this far without one? Options:
>
> - '' - empty string is not quite NULL but close
> - NULL - already a reserved word, may actually be correct?
>
> At a minimum I would like to throw a kinder error message -
> ExpressionToText:
>
> public Object visit(Literal expression, Object extraData) {
> ...
> } else {
> if (literal == null) {
> throw new NullPointerException("ECQL does not support null
> literal value");
> } else {
> String escaped = literal.toString().replaceAll("'", "''");
> output.append("'" + escaped + "'");
> }
> }
> return output;
> }
>
> Searching online is difficult as the presence of "IS NULL" and "IS NOT
> NULL".
> --
> Jody Garnett
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>
--
Regards, Andrea Aime
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