Typing of findAll seems to be missing the support of undefined values in where

Issue Description

When using sequelize with typescript, we run into the issue of not being able to use objects that have potentially undefined attributes for the where attribute of a findAll call.

What are you doing?

import Sequelize from 'sequelize';

class class user extends Sequelize.Model {
/* define your table here, it shouldn't matter for types */
}
const queryObj:{id:string, optionalValue?:string} = { id: 'someID'};

user.findAll({ where: queryObj }); // This is where the issue appears

What do you expect to happen?

According to my understanding of the discussion in issue #8583 the function should support undefined values as input. (If as null, or ignoring it completely, is irrelevant for this issue)

What is actually happening?

We get type errors, not allowing undefined values inside the whereobject.

Additional context

none

Environment

• Sequelize version: 5.19.6
• Node.js version: ^10, should not be relevant in any way
• Operating System: OS X and WIN 10, should also make no difference
• If TypeScript related: TypeScript version: 3.6.2

Issue Template Checklist

How does this problem relate to dialects?

• I think this problem happens regardless of the dialect.
• I think this problem happens only for the following dialect(s):
• I don’t know, I was using PUT-YOUR-DIALECT-HERE, with connector library version XXX and database version XXX

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start. (if it is simply adjusting the types)
• Yes, I have the time but I don’t know how to start, I would need guidance.
• No, I don’t have the time, although I believe I could do it if I had the time…
• No, I don’t have the time and I wouldn’t even know how to start.

[papb]

Changing the typing would allow runtime errors through accidentally added keys, that have the value undefined though.

Personally I think this drawback is a small price to pay.

I’ve found typescript#13195 though, so I guess there isn’t a better way until that issue is fixed (if ever?).

Let’s see what @SimonSchick thinks about it 😃

[Altimar21]

Hi ! Did you have time to check this one ?