Discussion on setting initial values for an array field in Sanity, including suggestions for using a custom input component and reviewing the content model.

{
      type: 'array',
      name: 'options',
      title: 'Opzioni',
      options: {
        sortable: false,
        list: [],
      },
      of: [{ type: 'string' }],
      initialValue: [{value: 'myValue', title: 'myTitle'}],
    },

// @ts-ignore
import sanityClient from 'part:@sanity/base/client';
export const client = sanityClient.withConfig({ apiVersion: 'v1' });
import { kebabCase } from 'lodash';

const getHeadquarters = async () => {
  const results = await client.fetch(`(*[_type == "formMultistepBuilder"] [0] {
    "list": headquarters.headquartersOptions
 }).list`);
  return results.map((res) => {
    return {
      value: kebabCase(res.name),
      title: res.name,
    };
  });
};

export default {
  name: 'formOperator',
  type: 'object',
  title: 'Operatore',
  fields: [
    ...,
    {
      type: 'array',
      name: 'headquarters',
      title: 'Sedi',
      options: {
        list: [],
      },
      of: [{ type: 'string' }],
      initialValue: async () => {
        return await getHeadquarters();
      },
    },
  ],
};

{
      type: 'array',
      name: 'headquarters',
      title: 'Sedi',
      options: {
        list: [],
      },
      of: [{ type: 'string' }],
      initialValue: ['test-1', 'test-2'],
    },

{
  type: 'array',
  name: 'headquarters',
  title: 'Sedi',
  options: {
    sortable: false,
    list: [
      {value: 'test-1', title: 'Test 1'},
      {value: 'test-2', title: 'Test 2'},
    ],
  },
  of: [{ type: 'string' }],
  initialValue: ['test-1', 'test-2'],
},

{
      type: 'array',
      name: 'headquarters',
      title: 'Sedi',
      options: {
        list: async () => {
          return await getHeadquarters();
        },
      },
      of: [{ type: 'string' }],
    },