Iterate inside the sequlize result set - promise

Question

I need to iterate over result set from the sequelize result. I have a code that works, but I think something is wrong with it, and it should not be done this way.
I have a feeling this is a blocking code.
This is the code that works:
models.Project.findAll({
where: {ProjectId: projectId}
})
.then(function (projects) {
//Iteration is here
var projectList = [];
projects.forEach(function (res) {
projectList.push(res.dataValues.PartId);
});
//then bulk lookup for the result
models.Customers.findAll({
where: {'id': {in: [projectList]}}
}).then(function (customers) {
reply(customers).code(200);
}, function (rejectedPromiseError) {
reply(rejectedPromiseError).code(401);
});
//reply(sameparts).code(200);
}, function (rejectedPromiseError) {
reply(rejectedPromiseError).code(401);
});
This iteration parts is done:
projects.forEach(function (res) {
projectList.push(res.dataValues.PartId);
});
And then this code is executed as another query:
models.Customers.findAll({
where: {'id': {in: [projectList]}}
}).then(function (customers) {
reply(customers).code(200);
}, function (rejectedPromiseError) {
reply(rejectedPromiseError).code(401);
});
How can I rearange it so it uses Promises?
EDIT (Possible solution):
After playing a bit, I believe I have implemented promises.
getAll: function (request, reply) {
var projectId = request.params.projectid;
var promises = [];
var post;
models.SamePart.findAll({
where: {ProjectId: projectId}
})
.then(function (sameparts) {
//Iteration is here
sameparts.forEach(function (res) {
promises.push(
Promise.all([
models.Parts.findAll({where: {id: res.dataValues.PartId}})
]))
});
//Bulk lookup for the parts that were marked as identical
return Promise.all(promises);
}).then(function (completepartslist) {
reply(completepartslist).code(200);
});
Is this a correct approach? It seems that completepartslist contains many unwanted objects, including Promise stuff. How can I flatten it, so to avoid complex for loops?

Answer 1

If you are using .then(), then you are, in all probability, already using promises.
Your original, working code doesn't appear to be blocking.
Your final getAll() looks like it should simplify to :
getAll: function (request, reply) {
models.SamePart.findAll({
where: { ProjectId: request.params.projectid }
}).then(function (sameparts) {
return Promise.all(sameparts.map(function (res) {
return models.Parts.findAll({ where: { id: res.dataValues.PartId } });
}));
}).then(function (completepartslist) {
reply(completepartslist).code(200);
});
}
However, you need to add error handling back in.

Answer 2

even more simplified
getAll: function (request, reply) {
models.SamePart.findAll({
where: { ProjectId: request.params.projectid }
}).reduce(function (completepartslist, sameparts) {
return models.Parts.findAll({ where: { id: sameparts.PartId } }).
then(function(res){
completepartslist.concat(res)
});
}), []);
}).then(function (completepartslist) {
reply(completepartslist).code(200);
});
}