createAssetValidator • tldraw Docs

Creates a validator for a specific asset record type. This factory function generates a complete validator that validates the entire asset record structure including the base properties (id, typeName, type, meta) and the type-specific props.

function createAssetValidator<Type extends string, Props extends JsonObject>(
  type: Type,
  props: T.Validator<Props>
): T.ObjectValidator<
  import('@tldraw/utils').Expand<
    {
      [P in
        | 'id'
        | 'meta'
        | 'typeName'
        | (undefined extends Props ? never : 'props')
        | (undefined extends Type ? never : 'type')]: {
        id: TLAssetId
        meta: JsonObject
        props: Props
        type: Type
        typeName: 'asset'
      }[P]
    } & {
      [P_1 in
        | (undefined extends Props ? 'props' : never)
        | (undefined extends Type ? 'type' : never)]?:
        | {
            id: TLAssetId
            meta: JsonObject
            props: Props
            type: Type
            typeName: 'asset'
          }[P_1]
        | undefined
    }
  >
>

Example

import { createAssetValidator, TLBaseAsset } from '@tldraw/tlschema'
import { T } from '@tldraw/validate'

// Define a custom asset type
type TLCustomAsset = TLBaseAsset<
  'custom',
  {
    url: string
    title: string
    description?: string
  }
>

// Create validator for the custom asset
const customAssetValidator = createAssetValidator(
  'custom',
  T.object({
    url: T.string,
    title: T.string,
    description: T.string.optional(),
  })
)

// Use the validator
const assetData = {
  id: 'asset:custom123',
  typeName: 'asset' as const,
  type: 'custom' as const,
  props: {
    url: 'https://example.com',
    title: 'My Custom Asset',
  },
  meta: {},
}

const validatedAsset = customAssetValidator.validate(assetData)

Parameters

Name	Description
`type`	`Type` The asset type identifier (e.g., 'image', 'video', 'bookmark')
`props`	`T.Validator<Props>` The validator for the asset's type-specific properties

Returns

T.ObjectValidator<
  import('@tldraw/utils').Expand<
    {
      [P in
        | 'id'
        | 'meta'
        | 'typeName'
        | (undefined extends Props ? never : 'props')
        | (undefined extends Type ? never : 'type')]: {
        id: TLAssetId
        meta: JsonObject
        props: Props
        type: Type
        typeName: 'asset'
      }[P]
    } & {
      [P_1 in
        | (undefined extends Props ? 'props' : never)
        | (undefined extends Type ? 'type' : never)]?:
        | {
            id: TLAssetId
            meta: JsonObject
            props: Props
            type: Type
            typeName: 'asset'
          }[P_1]
        | undefined
    }
  >
>

A complete validator for the asset record type