Access array index in custom input component with withDocument HOC

2 replies

Last updated: Dec 1, 2025

Hi! I'd like to get value's from the parent component of my custom input component. However I get stuck at the withDocument HOC, because I'm using the custom input component in an array of which I want the index in my custom input.

{
  name: "filters",
  title: "Filters",
  type: "array",
  of: [
    {
      type: "object",
      name: "category",
      fields: [
        {
          type: "reference",
          name: "category",
          to: [{ type: "category" }],
        },
        {
          name: "productFilters",
          type: "string",
          inputComponent: ProductFilter,
        },
      ],
    },
  ],
}

AI Update

I can help you access parent values and the array index in your custom input component! First, I need to correct the schema definition - in Sanity Studio v3, you need to use components: { input: ProductFilter } instead of inputComponent.

Corrected Schema Definition

{
  name: "filters",
  title: "Filters",
  type: "array",
  of: [
    {
      type: "object",
      name: "category",
      fields: [
        {
          type: "reference",
          name: "category",
          to: [{ type: "category" }],
        },
        {
          name: "productFilters",
          type: "string",
          components: {
            input: ProductFilter  // ✅ Correct syntax for Studio v3
          }
        },
      ],
    },
  ],
}

Accessing Array Index and Parent Values

The modern approach (replacing the deprecated withDocument HOC) is to use the path prop and the useFormValue() hook. Every custom input component receives a path prop that contains an array describing the field's location in the document, including the _key of array items.

Here's how to access both the array index and parent values:

import { useFormValue } from 'sanity'

const ProductFilter = (props) => {
  const { path, value, onChange } = props
  
  // The path will look like: ['filters', {_key: 'some-key'}, 'productFilters']
  // Extract the _key from the path
  const arrayItemKey = path.find(segment => segment._key)?._key
  
  // Get the full filters array from the document
  const filtersArray = useFormValue(['filters'])
  
  // Find the index of this item in the array
  const currentIndex = filtersArray?.findIndex(item => item._key === arrayItemKey) ?? -1
  
  // Access the parent category reference for this specific array item
  const parentCategory = useFormValue([...path.slice(0, -1), 'category'])
  
  return (
    <div>
      <p>Current array index: {currentIndex}</p>
      <p>Parent category reference: {parentCategory?._ref}</p>
      {/* Your custom input logic here */}
    </div>
  )
}

Alternative Approach: Using Parent Object

You can also get the parent object directly by slicing the path:

import { useFormValue } from 'sanity'

const ProductFilter = (props) => {
  const { path, value, onChange } = props
  
  // Get the parent object (the array item) by removing the last path segment
  const parentObject = useFormValue(path.slice(0, -1))
  
  // Get array item key from path
  const arrayItemKey = path.find(segment => segment._key)?._key
  
  // Get the filters array
  const filtersArray = useFormValue(['filters'])
  
  // Calculate the current index
  const currentIndex = filtersArray?.findIndex(item => item._key === arrayItemKey) ?? -1
  
  // Access the category reference from the parent object
  const categoryRef = parentObject?.category
  
  return (
    <div>
      <h3>Product Filter #{currentIndex + 1}</h3>
      <p>Category ID: {categoryRef?._ref}</p>
      <input 
        type="text" 
        value={value || ''} 
        onChange={(e) => onChange(e.target.value)}
      />
    </div>
  )
}

export default ProductFilter

Key Points

props.path gives you the breadcrumb trail to your field, including the _key of array items
useFormValue(path.slice(0, -1)) gives you the parent object by removing the last path segment
You can find the array index by comparing the _key from your path with all items in the array using findIndex()
useFormValue() replaces the deprecated withDocument HOC and gives you access to any value in the document
Use useFormValue([]) to access the entire document if needed

This approach works perfectly for nested objects inside arrays and gives you full access to parent values without needing the old HOC pattern!

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