Sequelize transaction always returning null - node.js

Question

I'm writing the backend for creating audit protocols. The user should be able to create criterias for the audit protocol. For this, i have the following backend-method to make sure, the protocol gets only created completely or the process of creating is canceled. It is possible to set several kinds of forms / criterias. But it could be, that only one kind of form is required. I do check that with the if-statement.
The creating works as expected. But the REST API always returns null to the clients. So i can't do further processing on the frontend regarding to the result of the creation process.
Technologies: Node.js and Sequelize. Frontend in angular / ionic. Database in mySQL.
I tried around with some transaction passing and return statements. I tried to compare it to a similiar code snippet, which works as expected.
exports.setAudit = (req, res, next) => {
trueFalseCriteria = req.body.trueFalseForms;
isShouldCriteria = req.body.isShouldForms;
generalCriteria = req.body.generalForms;
measurementCriteria = req.body.measurementForms;
toolId = req.body.toolId;
// Transaction is used to roll the whole transaction back if something wents wrong
return sequelize
.transaction(t => {
return audit
.create(
{
// Creating an audit referencing the tool
toolId: toolId
},
{ transaction: t }
)
.then(
// Getting the id of the audit that we just created
audit => {
return audit.id;
},
{ transaction: t }
)
.then(auditId => {
// Check wether the kind of form is used or not. If so, sequelize tries to do a bulk insert into the databases.
// Each bulk insert throws an error if it fails to cancel the whole transaction
if (trueFalseCriteria) {
console.log(1);
trueFalseCriteria.forEach(dataEl => {
dataEl.auditId = auditId;
});
trueFalseCriterion.bulkCreate(trueFalseCriteria).catch(err => {
// Throw error to cancel transaction
throw new Error(err);
});
}
if (isShouldCriteria) {
console.log(2);
isShouldCriteria.forEach(dataEl => {
dataEl.auditId = auditId;
});
isShouldCriterion.bulkCreate(isShouldCriteria).catch(err => {
// Throw error to cancel transaction
throw new Error(err);
});
}
if (generalCriteria) {
console.log(3);
generalCriteria.forEach(dataEl => {
dataEl.auditId = auditId;
});
generalCriterion.bulkCreate(generalCriteria).catch(err => {
// Throw error to cancel transaction
throw new Error(err);
});
}
if (measurementCriteria) {
console.log(4);
measurementCriteria.forEach(dataEl => {
dataEl.auditId = auditId;
});
measurementCriterion.bulkCreate(measurementCriteria).catch(err => {
// Throw error to cancel transaction
throw new Error(err);
});
}
}, { transaction: t });
})
.then(data => {
console.log(5);
res.status(200).json(data);
})
.catch(err => {
console.log(6);
if (!err.statusCode) {
err.statusCode = 500;
}
next(err);
});
};
Expected result: Http response with status code 200 on success
Actual result: null

Answer 1

I think you are missing a return for the last .then():
.then(auditId => {
// Check wether the kind of form is used or not. If so, sequelize tries to do a bulk insert into the databases.
.....
if (measurementCriteria) {
....
}
// RETURN SOMETHING HERE
}, { transaction: t });