I think you’re perhaps misunderstanding some of the core concepts of Meteor and its use of Fibers for sync-style programming.
It may be helpful to just go over some of the fundamentals.
On the server, Meteor code uses Fibers to achieve sync-style programming, in which callbacks are not used. However, Fibers are an example of coroutines, and have nothing to do do with Promises and async/await syntax. Meteor normally hides the underlying Fiber code for you, which makes it really easy to get started.
Meteor.wrapAsync ensures that a function having a callback with a signature of (error, result) runs within a Fiber. However, await is a Promise-based syntax and you cannot use await to get the result of a Fiber.
In Meteor, it’s fine to mix Fibers with Promises (and async/await), but it’s important to remember that they are completely different things and you should be aware of how they can be used together.
Consider an aynchronous function getData, which has a callback with an (error, result) signature. We can get the result in 4 ways (I’ve ignored error handling for simplicity):
// Get the result in the callback (traditional JavaScript)
getData((error, result) => {
console.log(result); // result is available here
});
// result is undefined (NOT available here)
// Use Meteor's Fibers (traditional Meteor)
const getDataWrapped = Meteor.wrapAsync(getData);
const result = getDataWrapped();
console.log(result);
// Use Promises
const getDataPromise = () => {
return new Promise(resolve => {
getData((error, result) => {
resolve(result);
});
});
}
getDataPromise()
.then(result => {
console.log(result); // Result is available here
)};
// Result is undefined (NOT available here)
// Using async/await
const getDataPromise = () => {
return new Promise(resolve => {
getData((error, result) => {
resolve(result);
});
});
}
const result = await getDataPromise();
You will notice that Meteor’s Fibers and async/await both result in sync-style programming, where the result is available “inline”.
However, there is a gotcha with async/await. You must wrap your sync-style await code in an async function. Results and “inlining” are only available inside that function.
Finally, on the client, there are no Fibers. You must use callbacks, or wrap callbacks in Promises to use async/await.
Take a look at these articles, where I go into a bit more depth:
