Support for JSON functions with mixed type/arity like json_build_object

[kelleyvanevert]

First of all: I love 🎉 that this library exists, and want to use it super much :)

But, in my project, I use a bunch of JSON stuff. I tried adding json_build_object via db.public.registerFunction, but can't get it to work due to its variable arity and typing. I'm thinking, maybe the overload-checking of registerFunction could be (optionally) inverted? E.g. instead of setting the args option, setting an option like acceptArgs: (args) => boolean? ..and then also passing the types along with the args when invoking the function somehow.

Has this idea, or the JSON functions, been floated before? I could put it some work into a fork, if this proposal or something similar sounds reasonable?

(Another issue I'm running into, btw, is using table.*, which I use a lot as in json_agg(table.*).)

[oguimbal]

We could think of something like that, yes. That makes sense.
Thanks for considering a contribution !

That said, I think it would be more like acceptArgs: (args: IType[]) => { returns: IType, args: IType[]} to give the chance to the end user to tell which kind of argument are actually accepted (so the runner can try to convert arguments before calling the types), and which is the return type of this overload.

For instance:

• If you declared jsonb_set the way you describe, the runner would call acceptArgs with types string, string, string when executing select jsonb_set('{"a":42}', '{b}', '55'), but jsonb, string, string when executing select jsonb_set('{"a":42}'::jsonb, '{b}', '55').
  👉 The actual implementation of this function would receive either serialized strings, or plain objects, depending on the performed query.

• If you do it the way I suggest, it should fix the problem:

  1. The acceptArgs will be given string, string, string, and will return {returns: json, args: [json, text, json]}
  2. The runner will force-convert the given arguments to the argument types specified by acceptArgs
  3. The fn implementation will receive correct types :)

As for the json_agg, that's another topic ! I suggest we discuss it on another thread 🙂

Sorry for the late reply.