There's no casting in javascript, so you cannot throw if "casting fails".
Typescript supports casting but that's only for compilation time, and you can do it like this:
const toDo = <IToDoDto> req.body;
// or
const toDo = req.body as IToDoDto;
You can check at runtime if the value is valid and if not throw an error, i.e.:
function isToDoDto(obj: any): obj is IToDoDto {
return typeof obj.description === "string" && typeof obj.status === "boolean";
}
@Post()
addToDo(@Response() res, @Request() req) {
if (!isToDoDto(req.body)) {
throw new Error("invalid request");
}
const toDo = req.body as IToDoDto;
this.toDoService.addToDo(toDo);
return res.status(HttpStatus.CREATED).end();
}
As @huyz pointed out, there's no need for the type assertion because isToDoDto is a type guard, so this should be enough:
if (!isToDoDto(req.body)) {
throw new Error("invalid request");
}
this.toDoService.addToDo(req.body);