The scenario: I am currently working with MongoDB and a REST API that communicates using JSON. MongoDB uses objects instead of identifiers for documents, but when these objects are stringified (such as in a response body), they get converted into strings.
The following example is quite condensed, but it serves the purpose of illustrating my question.
// This function should recursively convert all ObjectId types to string types
type JsonDocument<D> = {
[K in keyof D]: D[K] extends ObjectId ? string : D[K] extends object ? JsonDocument<D[K]> : D[K];
};
// The document type structure in the database
type FooDocument = {
_id: ObjectId;
updatedBy?: ObjectId;
};
// The document type structure in a response body
type FooJsonDocument = JsonDocument<FooDocument>;
// The expected structure of FooJsonDocument
type ExpectedResult = {
_id: string;
updatedBy?: string;
};
// The actual structure of FooJsonDocument
type ActualResult = {
_id: string;
updatedBy?: ObjectId;
};
All mandatory properties of type ObjectId are successfully changed to string, however, none of the optional properties of type ObjectId are modified.
How can I adjust JsonDocument to correctly handle optional properties as well?
I found this question on Typescript change property type recursively, but it doesn't address optional properties, so I believe it's not an exact duplicate. Nonetheless, it does provide some valuable insights.