FixRecursiveArraySchema TypeAlias
Workaround for fixing errors resulting from an issue with recursive ArrayNode schema exports.
To use, import via fluid-framework/alpha.
For more information about our API support guarantees, see here.
Signature
export type FixRecursiveArraySchema<T> = T extends TreeNodeSchema ? undefined : undefined;
Type Parameters
| Parameter | Description |
|---|---|
| T |
Remarks
Importing a recursive ArrayNode schema via a d.ts file can produce an error like error TS2310: Type 'RecursiveArray' recursively references itself as a base type. if using a tsconfig with "skipLibCheck": false.
This error occurs due to the TypeScript compiler splitting the class definition into two separate declarations in the d.ts file (one for the base, and one for the actual class). For unknown reasons, splitting the class declaration in this way breaks the recursive type handling, leading to the mentioned error.
This type always evaluates to undefined to ensure the dummy export (which doesn't exist at runtime) is typed correctly.
[TypeScript Issue 59550](https://github.com/microsoft/TypeScript/issues/59550) tracks a suggestion which would make this workaround unnecessary.
Example
Usage Since recursive type handling in TypeScript is order dependent, putting just the right kind of usages of the type before the declarations can cause it to not hit this error. For the case of ArrayNodes, this can be done via usage that looks like this:
This example should use a doc comment to ensure the workaround comment shows up in the intellisense for the dummy export, however doing so is impossible due to how this example is included in a doc comment.
// Workaround to avoid
// `error TS2310: Type 'RecursiveArray' recursively references itself as a base type.` in the d.ts file.
export declare const _RecursiveArrayWorkaround: FixRecursiveArraySchema<typeof RecursiveArray>;
export class RecursiveArray extends schema.arrayRecursive("RA", [() => RecursiveArray]) {}
{
type _check = ValidateRecursiveSchema<typeof RecursiveArray>;
}