Add ability to get field values

[doytch]

Are you submitting a bug report or a feature request?

Feature Request

What is the current behavior?

FieldArray components get a fields prop which is an object containing various methods.

What is the expected behavior?

It'd be great if it were possible to get the values of those, similar to redux-form's fields.getAll() functionality.

I realise that many problems can be solved by rendering the FieldArray's members as a Field and managing the value there. However, this pattern can be pretty ugly in some situations.

For example, here's an HOC that uses getAll() in production. The point of that HOC is mainly to abstract away the complexity in how our backends handle array member deletion from form fields. The complexity is that when we want to delete an array member object, we need to send back an array that contains an object with the member's id and a _delete key set to true.

The reason the backend operates that way is to basically support PATCH-like requests where an entire array doesn't need to be PUT, just the array members that have changed.

Other information

Similar issue: #13

[to-sh-1]

+1 would love this as well

[erikras]

Ha! This is already there (it's used in tests), but is totally undocumented and untyped.

I'll remedy that shortly.

[erikras]

Published fix in v3.1.1.

[nvaken]

@erikras Is it possible when using subscription={{}} value will be undefined? Is that as designed?

[vufrontend]

@nvaken I think it is impossible. We have to subscription value to call fields.value. It's weird