Transform decorator in class-transformer does not wait for asynchronous function and returns a Promise instead of the transformed value about class-transformer

[2astm]

the same

[diffy0712]

The Transform decorator signature calls for a function

class-transformer/src/decorators/transform.decorator.ts

Line 10 in 69cd8cc

transformFn: (params: TransformFnParams) => any,

with return type any, which is a bit misleading (as it will work with a promise in your case at least in ts). I do not see anything that is should support for async calls. it will not await for it I. (if it would support async I think the plainToInstance, instanceToInstance and instanceToPlain functions should support async as well.

The plainToInstance function should be called with the concrete data and awaited before it.

I think you would need something like

const resolvedValue = await something.organization;
const organisation = resolvedValue && 'name' in resolvedValue ? resolvedValue.name : null;

const user = plainToInstance(User, {..., organization});

I hope this helps

[diffy0712]

Closing as answered.
Note that there is an ongoing issue on async support. #549