Comparing parameters with constants

[ghuysmans]

Hi,

I'm building a search webservice using Caqti. The parser rejects my query if it compares input parameters with constants (Parse error at byte xxx: '=' is not allowed after parameter reference '?'); here's a simplified but meaningful example using ppx_rapper:

WHERE %string{mod_}='none' AND NOT EXISTS(SELECT * FROM required_module WHERE id_mission=m.id)
OR EXISTS(SELECT * FROM required_module WHERE id_mission=m.id AND mod_=%string{mod_}))

It can be reduced to a single line of code producing the same error message:

Caqti_query.of_string_exn "SELECT ?=1"

Would it be difficult to modify the parser to handle this case?

Thanks!

[paurkedal]

I suggest adding spaces around the equality sign. Sequences of starting with ? followed by operator characters are reserved for future extensions, though the issue gets a bit obscured when using ppx_rapper, making it less obvious why it fails. I'm considering whether the best solution to that may be the adjust ppx_rappers code generator to insert a space in this case.

[ghuysmans]

Thanks, I completely overlooked that!