Firestore: Support Custom Marsheling and Unmarsheling

[giautm]

I wish firestore support custom data type as (google/uuid) via custom marshal/unmarshal.

Currently: firestore: cannot convert type uuid.UUID to value

[jeanbza]

Could you provide a small code snippet how you're passing google/uuid to firestore?

[giautm]

I added a field named ID to structure. Then ran into the error.

type State struct {
	ID         uuid.UUID `firestore:"id"`
	Capital    string    `firestore:"capital"`
	Population float64   `firestore:"pop"` // in millions
}

[giautm]

Hi @jadekler , Do you have any comment?

[jeanbza]

Looks like the issue is that we don't handle arrays properly (uuid.UUID is a byte array). I've submitted a CL to fix this: https://code-review.googlesource.com/c/gocloud/+/40996

[giautm]

Yes, This fix worked. But not the way that I want. UUID was converted to an array of bytes.

[jeanbza]

Right, that's because uuid.UUID is an array of bytes. :) If you're looking for a string representation, you will have to change the type and do the string conversion yourself.

[giautm]

@jadekler : If firestore support encoding(https://golang.org/pkg/encoding/) package, we can do it easier

[giautm]

Hi @jadekler , I created a PR to support encoding/text https://github.com/googleapis/google-cloud-go/pull/1425/files

[marwan-at-work]

@giautm @jadekler I stumbled upon this for a similar (but not exact) reason: it would be really helpful if the client also supported custom JSON Marshaler/Unmarshaler interfaces

Do you mind re-opening this issue or maybe I can create a new/separate issue for it? Thanks

[jeanbza]

@marwan-at-work Yes, please file a new issue.

[marwan-at-work]

@jadekler done (#1475)
thanks!