NodeJS: Unhandled Promise Rejection at the end of a method - node.js

Question

At the moment, I'm working on a RESTful-API with express and mongoose and I now have a problem.
First, my method:
public create() : Promise<UserDocument> {
return new Promise((user) => {
User.exists(this.username).then((exists) => {
if (exists) {
throw Errors.mongoose.user_already_exists;
} else {
UserModel.create(this.toIUser()).then((result) => {
user(result);
}).catch(() => {
throw Errors.mongoose.user_create
});
}
}).catch((error) => {
throw error;
})
});
}
I get a unhandled promise rejections when I execute this method. This happens even if I handle the error when I execute the method like this:
User.fromIUser(user).create().then(() => {
return response.status(200).send({
message: "Created",
user
});
}).catch((error) => {
return response.status(500).send({
message: error
});
});
Full stacktrace:
(node:23992) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): User already exists
(node:23992) DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
How i can avoid this situation?
Thanks for your help,
felixoi

Answer 1

I found the solution! Just use "resolve, request" for creating a promise.
Here is now my method:
public create() : Promise<any> {
return new Promise((resolve, reject) => {
User.exists(this.username).then((exists) => {
if (exists) {
reject( Errors.mongoose.user_already_exists);
} else {
UserModel.create(this.toIUser()).then((result) => {
resolve(result);
}).catch(() => {
reject(Errors.mongoose.user_create);
});
}
}).catch((error) => {
reject(error);
})
})
}
If you call the method now you can use the catch() method and everything works! Call it like this:
User.fromIUser(user).create().then((user) => {
return response.status(200).send({
message: "Created",
user
});
}).catch((error) => {
return response.status(500).send({
message: error
})
})