uploadLink.js

// METHOD #1 - More performant/preferred

/**
 * Apollo Terminating link
 * The split will skip Batching if an
 * operation's context contains hasUpload: true
 */
const httpLink = ApolloLink.split(
  operation => operation.getContext().hasUpload,
  createUploadLink(OPTS),
  new BatchHttpLink(OPTS)
)

/**
 * Then within a mutation component, specify the context
 * with hasUpload to activate the Upload link.
 */
const { data } = await uploadMutation({
  variables: { file },
  context: {
    hasUpload: true, // activate Upload link
  }
})


// METHOD #2 - Doesn't require dev interaction, but less performant.

const isObject = node => typeof node === 'object' && node !== null

const hasFiles = (node, isRecursive) => {
  if (!isRecursive) {
    if (typeof File === undefined || typeof Blob === undefined) return false
  }

  const keys = Object.keys(node)
  let i = 0
  let exit
  let found
  
  try {
    while (!found && !exit && i < keys.length) {
      if (!isObject(node[keys[i]])) {
        i++
      } else if (node[keys[i]] instanceof File || node[keys[i]] instanceof Blob) {
        found = true
      } else if (hasFiles(node[keys[i]], true)) {
        found = true
      } else {
        i++
      }
    }
  } catch (e) {
    exit = true
  }
  return found
}

const httpLink = ApolloLink.split(
  ({ variables }) => hasFiles(variables),
  createUploadLink(UPLOAD_OPTS),
  ApolloLink.from([createOmitTypenameLink(), new BatchHttpLink(BATCH_OPTS)])
)