feat(actions): uniqueSet() for transaction capability

[prescottprue]

What is the feature?
Exposing a uniqueSet() in props.firestore that is similar to the one within props.firebase would be fantastic for use cases where multiple clients are writing to the same document.

Originally requested in 419 of react-redux-firebase by @giles-t

What version would this apply to?

Do you have thoughts/examples on how the feature would be used (i.e. API)?

uniqueSet would match what react-redux-firebase does for RTDB, so that makes the most sense

[illuminist]

const uniqueSet = (docRef, value, onComplete) => firebase
  .runTransaction(
    transaction => transaction
      .get(docRef)
      .then(docSnap => {
        if (docSnap.exists) {
          const newError = new Error('Document already exists.')
          if (onComplete) onComplete(newError)
          return Promise.reject(newError)
        }
        return transaction.set(value)
      })
    }
  )
  .then(() => {
    if (onComplete) onComplete()
  })
}

What do you think? Haven't tested yet. Just want to know if this is a desire behavior or not.

[prescottprue]

Yup, that is the desired behavior @illuminist, thanks for posting. Feel free to make a PR with the changes, and we can get them in 😄

[illuminist]

Does it need to use redux-firestore function? Somehow I feel like I need to make it accept QueryOption like the other functions.

[prescottprue]

@illuminist yeah, it would live in redux-firestore since that is where the other Firestore specific actions live. Accepting QueryOption like you mentioned would be good to match the other call signatures