Add getMany: get multiple documents by id

[thomastoye]

Didn't find any test instructions, some help to finish this would be appreciated :)

[kossnocorp]

Wow, I work with Firestore since the day it was released and I didn't know this ability exists! Thank you so much for the PR! Sorry for nonexisting docs about contributing and testing. Let me fix that and write you an instruction on how you can run tests.

[kossnocorp]

Here we go: https://github.com/kossnocorp/typesaurus/blob/master/CONTRIBUTING.md

Please tell me if you have any questions regarding it.

[kossnocorp]

Please fix the undefined problem.

[thomastoye]

What do you think about the onMissing strategy like this?

async function getMany<Model>(
  collection: Collection<Model>,
  ids: readonly string[],
  onMissing: (id: string) => Model = (id) => { throw new Error(`Missing document with id ${id}`) }
): Promise<Doc<Model>[]> {
  ...

[thomastoye]

Hi @kossnocorp, I added tests and fixed the undefined problem.

[kossnocorp]

What do you think about the onMissing strategy like this?

I love it, it totally makes sense!

[kossnocorp]

Please accept my fixes: thomastoye#1

[kossnocorp]

Thank you a lot for the PR! I'll ship it with a new version.

[kossnocorp]

I've shipped getMany with v2.1.0