[RFC]: Add support for Realtime Cells

[Tobbe]

How about Cedar supports cells that instead of just firing off a gql query when they load, they set up a subscription (or a live query). So that their data is always up-to-date.

It'd be cool if they could just detect if there's a second subscription query exported in the cell, and then also wire up useSubscription() in addition to useQuery()

Outstanding questions:

• Are all the same states needed as for regular queries?
• How do we make sure users don't over-reach for subscriptions (when a simple polling solution would suffice)
• What would support for live queries look like?
• What updates would be needed to our generators?

[Tobbe]

Here's an AI generated hook that does both query and sub. Not sure if that's helpful or not

import { useQuery, useSubscription } from '@apollo/client'
import { useState, useEffect } from 'react'

export function useQueryWithSubscription(query, subscription, options = {}) {
  const [data, setData] = useState(null)
  
  const queryResult = useQuery(query, options)
  const subscriptionResult = useSubscription(subscription, {
    shouldResubscribe: true,
    ...options
  })
  
  useEffect(() => {
    if (queryResult.data && !data) {
      // Extract the relevant field from query result
      const fieldName = Object.keys(queryResult.data)[0]
      setData(queryResult.data[fieldName])
    }
  }, [queryResult.data, data])
  
  useEffect(() => {
    if (subscriptionResult.data) {
      // Extract the relevant field from subscription result
      const fieldName = Object.keys(subscriptionResult.data)[0]
      setData(subscriptionResult.data[fieldName])
    }
  }, [subscriptionResult.data])
  
  return {
    data,
    loading: queryResult.loading,
    error: queryResult.error || subscriptionResult.error
  }
}

[github-actions]

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