Example of custom document actions on Sanity. See documentation for more https://www.sanity.io/docs/document-actions-api

actions.js

import defaultResolve from "part:@sanity/base/document-actions";
import Custom from "./Custom";

// All actions are just functions that receive props (current document
// information) and return an object with at least a label and an onHandle
// function that is invoked if the editor wants to perform the action. See
// documentation for more possibilities.
// https://www.sanity.io/docs/document-actions-api
function MinimalCustomActionExample(props) {
  return {
    label: "Click me",
    onHandle: () => {
      alert("Editor performed action")
    }
  }
}

// This is how Sanity determines which document actions to display to an Editor.
// It calls this function, and whatever actions are returned are presented.
export default function resolveDocumentActions(props) {

  // For this example, we will return the built in document actions and our own
  // custom actions appended (if we returned an empty array here, no document
  // would have any available action).  The first action in the list is the
  // main action, and this is by default the Publish button, but you are free
  // to re-arrange that here as you see fit.  You can also inspect `props` to
  // determine which actions you want to show, and maybe which action should be
  // the default in a given case.
  const builtIn = defaultResolve(props);
  return [...builtIn, Custom, MinimalCustomActionExample];
}

Custom.js

import React from "react";
import sanityClient from "part:@sanity/base/client";
import userStore from "part:@sanity/base/user";

// A more involved custom action example, doing some queries etc.

export default function Custom(props) {
  // const {draft, published, id, type} = props
 
  // Common operation in custom actions are to inspect the document (draft ||
  // published) and make decisions on if the action should be enabled or not,
  // or use some of its fields for custom business logic. If you want to do
  // custom mutations to the document, inspect its validation status etc,
  // please have a look at the built in hooks
  // https://www.sanity.io/docs/studio-react-hooks

  // Perhaps use another sanity API client to query a different dataset
  const dynamicSanityClient = sanityClient.withConfig({
    apiVersion: "2021-04-15",
    dataset: "sync",
  });

  return {
    disabled: false,
    label: "Custom",
    // This function is what happends when editors perform your action by clicking the button
    onHandle: async () => {
      // You may do whatever you want in here

      return Promise.all([
        dynamicSanityClient.fetch("count(*)"),
        // Get some info about the current user
        userStore.getUser("me"),
      ]).then(([count, user]) => {
        alert(
          `Hello ${user.displayName}! There are ${count} documents in the other dataset`
        );
      })
    }
  };
}

sanity.json

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