List filter crashes when you switch a relationship filter from exists to equals

[rishabhmehta]

What?

On a relationship field, set the filter to exists → True, then switch the operator to equals without touching the value. The list view goes blank. The URL ends up with where[or][0][and][0][authors][equals]=true, and on Postgres the server throws:

params: version.authors,true,NaN,10
error: invalid input syntax for type integer: "NaN"

If you go straight to Authors → equals and pick a user, it works fine. So it's the value carried over from exists that does it.

Why?

I think this is what #10648 was about. #11136 closed that one by resetting the value when the new operator can't take it, but keeping it when it can, so flipping between equals and not_equals doesn't wipe what you typed.

The catch is in getOperatorValueTypes. equals is 'any', and exists stores its value as the string 'true' / 'false' (there's a comment about that in validOperators), so the leftover 'true' passes as a valid value for equals. The check only looks at the operator you're switching to, so it has no idea the value came from exists. On a relationship field that string then gets cast for the integer id, comes out as NaN, and Postgres rejects it.

Same on 3.90.1, which was the latest when I checked. I ran into it on 3.87.1 in a real project and then reproduced it on a blank template.

The repro has drafts on, which is why the failing query hits _posts_v, and I haven't tried it without them. Also only tested on Postgres, so no idea what Mongo does.

How?

Same rule as #11136: only reset when the value stops making sense. A value that came from exists doesn't make sense for any other operator, so reset it. equals / not_equals / in would keep their value like they do now. Haven't checked whether other operator pairs have the same problem.

@jacobsfletch @JessRynkar was equals: 'any' meant to cover this, or did exists just not get thought of as a starting point? If it's a bug I'll open a PR.

Reproduction

Repo: https://github.com/rishabhmehta/payload-filter-repro

1. pnpm install, point DATABASE_URL at a Postgres db, pnpm dev, create two users.
2. Posts → Filters → Add Filter.
3. Authors, exists, True.
4. Switch the operator to equals.

List view goes blank and the server logs invalid input syntax for type integer: "NaN".

Areas: area: ui, db: postgres

Environment: Payload 3.90.1, @payloadcms/db-postgres 3.90.1, Next 16.3.3, Node v24.11.1, pnpm 10.33.2, macOS 26.5.2