More convenient way to implement raw/custom operators

[kblomster]

Problem

When we want to call a function that Jet doesn't support natively, we can use jet.Func("funcname", SomeExpression, ...). This is convenient; only the function name needs to be a hardcoded string, while the arguments can be any Jet expression. Jet will take care of serializing the expressions to SQL.

However, if we want to use an operator that Jet doesn't support, say for example ILIKE (aka. ~~*) in postgres, then we have to resort to jet.Raw, which is not nearly as convenient: we have to serialize the operands ourselves in some way. Expressions that are actual columns are easy enough, we can just say someColumn.Name() and put that into the raw string, but if it's a more complex expression I don't see an obvious way of doing it.

Proposed solution

I see that internally Jet does have a function that does almost exactly what I'd like: NewBinaryOperatorExpression(lhs Serializer, rhs Serializer, operator string). If the public API exposed a wrapper around this, something like jet.BinaryOperator(lhs jet.Expression, rhs jet.Expression, operator string) jet.Expression then I could do things like this to implement my own operators:

func ILIKE(lhs jet.StringExpression, rhs jet.StringExpression) jet.BoolExpression {
    return jet.BoolExp(jet.BinaryOperator(lhs, rhs, "~~*"))
}

[go-jet]

Makes sense.

[kblomster]

Thanks! I'm happy with this so I'll close the issue :)

[kblomster]

Actually, reopening this. I've cloned the wiki and added documentation about BinaryOperator to the FAQ in my cloned repo: https://github.com/kblomster/jet/wiki/FAQ#how-to-use-custom-or-currently-unsupported-sql-operators

I'm not sure how easy it is to get wiki changes upstreamed, but this gist suggests a workflow at least: https://gist.github.com/omaraboumrad/35654da0a376c57a2e0ab4d92ad0c339#core-contributors

Let me know if you have feedback on the docs.

[go-jet]

Merged. :+1:

[kblomster]

Thanks! With that I'll consider this issue well addressed. :)