I am trying to write this code with Promise. but I don't know how to write promise inside Promise and loop. I tried to think like this but insertBook function become asynchronously. How can I get bookId synchronously?
update: function(items, quotationId) {
return new Promise(function(resolve, reject) {
knex.transaction(function (t) {
Promise.bind(result).then(function() {
return process1
}).then(function() {
return process2
}).then(function() {
var promises = items.map(function (item) {
var people = _.pick(item, 'familyName', 'firstNumber', 'tel');
if (item.type === 'book') {
var book = _.pick(item, 'name', 'bookNumber', 'author');
var bookId = insertBook(t, book);
var values = _.merge({}, people, {quotation: quotationId}, {book: bookId});
} else {
var values = _.merge({}, people, {quotation: quotationId});
}
return AModel.validateFor(values);
});
return Promise.all(promises);
}).then(function(items) {
var insertValues = items.map(function (item) {
return People.columnize(item);
});
return knex('people').transacting(t).insert(insertValues);
}).then(function() {
return process5
}).then(function() {
...........
}).then(function() {
t.commit(this);
}).catch(t.rollback);
}).then(function (res) {
resolve(res);
}).catch(function(err) {
reject(err);
});
});
}
function insertBook(t, book){
return Promise.bind(this).then(function () {
return Book.columnizeFor(book);
}).then(function (value) {
return knex('book').transacting(t).insert(value, "id");
});
}
You dont need to get bookid synchronously, you can handle it asynchronously correctly. Also, it is possible you want all book insertions happen sequentially, so I refactored the Promise.all
part. (done that just to give you an idea. Promise.all
should work fine if insertions in parallel are allowed). Furthermore, I think you shouldn't use Promise.bind
. To be honest I dont even know what it does, one thing for sure: it doesn't work with standard promises. So here is an example how I think it should work:
update: function(items) {
return new Promise(function(resolve) {
knex.transaction(function (t) {
resolve(Promise.resolve().then(function() {
return process1;
}).then(function() {
return process2;
}).then(function() {
var q = Promise.resolve(), results = [];
items.forEach(function (item) {
q = q.then(function() {
var book = _.pick(item, 'name', 'bookNumber', 'author');
return insertBook(t, book);
}).then(function(bookId) {
var people = _.pick(item, 'familyName', 'firstNumber', 'tel');
var values = _.merge({}, people, {book: bookId});
return AModel.validateFor(values);
}).then(function(item) {
results.push(item);
});
});
return q.then(function() {
return results;
});
}).then(function(items) {
return process4
}).then(function() {
t.commit(result);
}).catch(function(e) {
t.rollback(e);
throw e;
}));
});
});
}
function insertBook(t, book){
return Promise.resolve().then(function () {
return Book.columnizeFor(book);
}).then(function (value) {
return knex('book').transacting(t).insert(value, "id");
});
}