Set slug on publish with referenced field value

{
  "parts": [
    {
      "implements": "part:@sanity/base/document-actions/resolver",
      "path": "./schemas/documentActions.js"
    }
  ]
}

// schemas/documentActions.js

import defaultResolve, {
    PublishAction,
  } from 'part:@sanity/base/document-actions';
  import SetSlugAndPublishAction from "./actions/setSlugAndPublishAction.js"
  
  /// Publish Actions
  export default function useDocumentActions(props) {
    /// Leave the code below commented out to run this action for all documents
    /// Uncomment the code below to restrict this action to specific documents only
    // if (["tag"].indexOf(props.type) !== -1) {
      return defaultResolve(props).map((Action) =>
        Action === PublishAction ? SetSlugAndPublishAction : Action
      );
    // }

    // return defaultResolve(props)
  }

// schemas/actions/setSlugAndPublishAction.js

import {useState, useEffect} from 'react'
import {useDocumentOperation} from '@sanity/react-hooks'
import sanityClient from '@sanity/client'

const sanityClientConfig = {
  projectId: process.env.SANITY_STUDIO_API_PROJECT_ID,
  dataset: process.env.SANITY_STUDIO_API_DATASET,
  token: process.env.SANITY_STUDIO_API_TOKEN,
  useCdn: true,
}

export default function SetSlugAndPublishAction(props) {
  const {patch, publish} = useDocumentOperation(props.id, props.type)
  const [isPublishing, setIsPublishing] = useState(false)
  
  useEffect(() => {
    // if the isPublishing state was set to true and the draft has changed
    // to become `null` the document has been published
    if (isPublishing && !props.draft) {
      setIsPublishing(false)
    }
  }, [props.draft])
  
  return {
    disabled: publish.disabled,
    label: isPublishing ? 'Publishing…' : 'Publish',
    onHandle: async () => {
      // This will update the button text 
      setIsPublishing(true)

      /// Get the sanity client for fetching referenced field values
      const client = sanityClient(sanityClientConfig)

      /// Set the initial slug value to the name field
      let slug = props.draft.name
      
      /// Set the slug based on the document type
      switch (props.type) {
        case 'tag':
          /// The type of the reference field to get the value from
          const referenceNameType = 'category'
          /// Query for the referenced "category" and return the "name" field of that referenced document
          const query = `*[_type == "${referenceNameType}" && _id == $nameRef][0] {name}`
          /// Start with the "category: reference id in the draft
          let referenceName = props.draft.category._ref
          /// Fetch the category referenced in this document
          await client.fetch(query, {nameRef: referenceName}).then(category => {
            /// Set the referenceName to the category.name field
            referenceName = !!category ? category.name : referenceName
          })

          /// For the "tag" type document, set the slug to [category.name]-[type]-[number]
          slug = `${referenceName}-${props.type}-${props.draft.number}`
          /// Set name field for the "tag" type document to be the same value as the slug
          patch.execute([{set: { name: slug.toLowerCase() }}])
          break;

        default:
          /// Doing nothing? Consider deleting this switch statement to simplify your code.
          break;
      }

      /// Set the slug field of this document
      patch.execute([{set: { slug: { _type: 'slug', current: slug.toLowerCase() }}}])
      
      // Perform the publish
      publish.execute()
      
      // Signal that the action is completed
      props.onComplete() 
    }
  }
}