I'm new to sequelize. I'm using mysql as my database. I've a sequelize query which finds the email-id from the database. By using the result of this query, I got the ID of that row. Now I need to return this value. Can someone please help me how to do that.
Here is my code.
var userId = getUserId(email_address);
function getUserId(email_address) {
models.users.findOne({
where: {
email: email_address
}
}).then(function(result) {
if (result) {
var applicantId = result.id;
return applicantId; // This is what I need to do
} else {
console.log("Could not find Email");
}
});
}
Here I need to return the variable applicantId to the calling function.
The Sequelize call to the database is asynchronous so you need to alter your code a bit to work with promises. Something like this:
function getUserId(email_address) {
return models.users.findOne({
where: {
email: email_address
}
});
}
getUserId("some#email.com").then(function(result){
console.log(result.id);
});
check out this fiddle that mocks your scenario
Related
I have a function in node.js that looks like this:
exports.getAllFlights = function(getRequest) {
// this is the package from npm called "async"
async.map(clients, getFlight, function(err, results) {
getRequest(results);
});
}
The variable clients should be a JSON that looks like this:
{'"A4Q"': 'JZA8187', "'B7P"': 'DAL2098' }.
I expect that the map function will pass the individual indices of the array of the variable clients to getFlight. However, instead it passed the values of that each(ex: 'DAL2098', 'JZA8187' and so on).
Is this the expected functionality? Is there a function in async that will do what I want?
The signature of getFlight is getFlight(identifier, callback). Identifier is what is currently messed up. It returns callback(null, rtn). Null reprsents the nonexistence of an error, rtn represents the JSON that my function produces.
Yes, that's the expected result. The documentation is not very clear but all iterating functions of async.js pass the values of the iterable, not the keys. There is the eachOf series of functions that pass both key and value. For example:
async.eachOf(clients, function (value, key, callback) {
// process each client here
});
Unfortunately there is no mapOf.
If you don't mind not doing things in parallel you can use eachOfSeries:
var results = [];
async.eachOfSeries(clients, function (value, key, callback) {
// do what getFlight needs to do and append to results array
}, function(err) {
getRequest(results);
});
Another (IMHO better) workaround is to use proper arrays:
var clients = [{'A4Q': 'JZA8187'},{'B7P': 'DAL2098'}];
Then use your original logic. However, I'd prefer to use a structure like the following:
var clients = [
{key: 'A4Q', val: 'JZA8187'},
{key: 'B7P', val: 'DAL2098'}
];
First create a custom event. Attach a listener for return data. then process it.
var EventEmitter = require('events');
var myEmitter = new EventEmitter();
myEmitter.emit('clients_data',{'"A4Q"': 'JZA8187'}); //emit your event where ever
myEmitter.on('clients_data', (obj) => {
if (typeof obj !=='undefined') {
if (obj.contructor === Object && Object.keys(obj).lenth == 0) {
console.log('empty');
} else {
for(var key in obj) {
var value = obj[key];
//do what you want here
}
}
}
});
Well, you need to format your clients object properly before you can use it with async.map(). Lodash _.map() can help you:
var client_list = _.map(clients, function(value, key) {
var item = {};
item[key] = value;
return item;
});
After that, you will have an array like:
[ { A4Q: 'JZA8187' }, { B7P: 'DAL2098' } ]
Then, you can use async.map():
exports.getAllFlights = function(getRequest) {
async.map(client_list, getFlight, function(err, results) {
getRequest(results);
});
};
I've been struggling with the Bluebird promise library and MySQL for the past week. I'm constantly finding that what doco there is assumes I'm totally immersed in their terminology and often only gives half the answer in it's examples, or none at all. Leaving me hanging trying to figure out how to use it.
Currently I'm trying to execute a series of SQL commands for creating a database record inside a transaction. I'm using this code:
var Promise = require('bluebird');
var mysql = require('mysql');
Promise.promisifyAll(mysql);
Promise.promisifyAll(require('mysql/lib/Connection').prototype);
Promise.promisifyAll(require('mysql/lib/Pool').prototype);
function getConnection() {
return pool.getConnectionAsync().disposer(function (connection) {
connection.release();
});
}
function getTransaction(connection) {
return connection.beginTransactionAsync().disposer(function (tx, promise) {
if (promise.isFulfilled()) {
tx.commitAsync();
} else {
tx.rollbackAsync();
}
});
}
Database.prototype.addStory = function (projectId, title, text) {
return Promise.using(getConnection(), function (connection) {
return Promise.using(getTransaction(connection), function () {
return connection.queryAsync('INSERT INTO story SELECT ?, MAX(storyNumber) + 1, ?, ?, 0 FROM story WHERE projectID = ?',
[projectId, title, text, projectId])
.then(connection.queryAsync('select LAST_INSERT_ID()'))
.then(function (rows) {
debug("Returning story for %s", rows[0]);
return getStory(connection, rows[0]);
});
});
});
}
And currently I'm getting this error:
TypeError: tx.rollbackAsync is not a function
From what I've read my code should work. Does anyone know what's wrong with it?
Thanks for the answers guys.
I've now found the Knex API which solves all my problems with less code.
I've found the initial error and used this approach in my code:
function getTransaction(connection) {
return connection.beginTransactionAsync().disposer(function (tx, promise) {
if (promise.isFulfilled()) {
connection.commitAsync();
} else {
connection.rollbackAsync();
}
});
}
I'm pretty new to nodejs and I'm having some difficulties to understand how to use the mysql connection object.
My problem is not in the code but in the design pattern.
lets say I have a user module
module.exports = function(){
return{
id: "",
load: function(id){
var sql = 'SELECT * from users where id = '+ DB.escape(id);
console.log(1);
DB.query(sql, function (err, rows) {
this.id = rows[0].id; // not working
console.log(rows[0].id); // prints the id 4
console.log(2);
});
console.log(3);
}
}
}
from outside the module i run the next code
var user = require('../modules/user');
var selected_user = user();
console.log("entering users me route");
selected_user.load(4);
console.log("user id is " + selected_user.id); //This does not print the id 4
when I run the code, the console logs 1, then 3, and then 2.
This is due to the asynchronous flow of node js.
But if I'm building a website, and I need the query to end in order to populate my user object before I send the HTML to the browser???
What's the right way to do it ?
Also when I try to populate the id property of user in the id i receive from the DB it does not work.
Any ideas?
Thanks
There are several ways to do this. I would go with Promises.
Suppose you have an asynchronous function "getUsers".
It looks like this:
function getUsers() {
longQuery(function(err, result){
// What to do with result?
});
You need to rewrite it to be able to use the result.
Let's try:
function getUsers() {
return new Promise(function(resolve, reject) {
longQuery(function(err, result){
if(err) reject(err)
else resolve(result)
});
});
Now this function returns a promise. What do we do with that promise?
function handleRequest(req, res) {
getUsers().then(function(result) {
// Do stuff with result
res.send(myProcessedData);
}).catch(function(err) {console.log(err)};
}
This could also have been done with callbacks, passing the response object as a parameter to the query function, and many other ways, but I think promises are a very elegant way for handling this.
this.id = rows[0].id; // not working
The above line is not working because you are setting it to this.id from inside a callback function. When you are inside a callback function this does not mean the this in the main object.
For more discussion about this: see How to access the correct `this` context inside a callback?
To tackle the asynchronous nature of javascript you can either use promise like the answer from matanso or you can pass a callback function to your load method. So your load: function(id) method will be load: function(id, callbackFunction) and call the callback function when you get all the data that you need.
I have a webserver with JSON data in it. This is what my data looks like
[
{
iduser: 1,
username: "joe",
password: "****"
},
{
iduser: 2,
username: "gina",
password: "****"
}
]
In my app I take some user input and wish to compare it to the username and password field. Here is where I check the data
.service('LoginService', function ($q, $http) {
return {
loginUser: function (name, pw) {
var deferred = $q.defer();
var promise = deferred.promise;
var user_data = $http.get("http://<my ip address>:<port>/login");
user_data.then(function ($scope, result) {
$scope.user = result.data;
})
for (var x in $scope.user) {
if (name == x.username && pw == x.password) {
deferred.resolve('Welcome ' + name + '!');
} else {
deferred.reject('Wrong credentials.');
}
}
promise.success = function (fn) {
promise.then(fn);
return promise;
}
promise.error = function (fn) {
promise.then(null, fn);
return promise;
}
return promise;
}
}
})
I am still learning angularJS and I know this is not a secure way to check the data I just want this loop to work.
My understanding of what I have here is that $scope.user holds my JSON data. Then the data is cycled through with the for loop and the user input name is compared to the field username of each iteration. But this is not the case as I am getting a fail every time.
I'm almost certain its a syntax error, but I don't know JavaScript or AngularJS well enough to find the problem. Any help is really appreciated, Thanks.
Edit 1
After what Nujabes said I made some changes since I don't need $scope.
//previous code the same
user_data.then(function (result) {
var user = result.data;
})
for (var x in user) {
if (name == x.username && pw == x.password) {
//prior code the same
I don't think var can hold the data and thats why I'm still getting errors. I think it should be in an array.
I think your syntax error is that you omit $scope.
You should inject $scope service to this line:
.service('LoginService',function($q,$http,$scope){ ...
});
And this code :
user_data.then(function ($scope, result) {
$scope.user = result.data;
});
Omit the $scope.
->
user_data.then(function (result) {
$scope.user = result.data;
});
like this.
Give it a try.
I hope it work.
(However, why do you want to use $scope service in your 'service'?
I think, defining local value and returning some method is a better choice.
and you use the $scope service in your 'controller'.)
$scope.user you are trying to loop through is array right ?
using (for/in) will store the key in the variable x which is in your case the index of each element (0,1,2,..) , to loop through arrays use (for/of) like this :
for (var value of array)
this will give you the values ...
I'm using Sequelize in my Nodejs project and I found a problem that I'm having a hard time to solve.
Basically I have a cron that gets an array of objects from a server than inserts it on my database as a object ( for this case, cartoons ). But if I already have one of the objects, I have to update it.
Basically I have a array of objects and a could use the BulkCreate() method. But as the Cron starts again, it doesn't solve it so I was needing some sort of update with an upsert true flag. And the main issue: I must have a callback that fires just once after all these creates or updates. Does anyone have an idea of how can I do that? Iterate over an array of object.. creating or updating it and then getting a single callback after?
Thanks for the attention
From the docs, you don't need to query where to perform the update once you have the object. Also, the use of promise should simplify callbacks:
Implementation
function upsert(values, condition) {
return Model
.findOne({ where: condition })
.then(function(obj) {
// update
if(obj)
return obj.update(values);
// insert
return Model.create(values);
})
}
Usage
upsert({ first_name: 'Taku' }, { id: 1234 }).then(function(result){
res.status(200).send({success: true});
});
Note
This operation is not atomic.
Creates 2 network calls.
which means it is advisable to re-think the approach and probably just update values in one network call and either:
Look at the value returned (i.e. rows_affected) and decide what to do.
Return success if update operation succeeds. This is because whether the resource exists is not within this service's responsibility.
You can use upsert
It's way easier.
Implementation details:
MySQL - Implemented as a single query INSERT values ON DUPLICATE KEY UPDATE values
PostgreSQL - Implemented as a temporary function with exception handling: INSERT EXCEPTION WHEN unique_constraint UPDATE
SQLite - Implemented as two queries INSERT; UPDATE. This means that the update is executed regardless of whether the row already
existed or not
MSSQL - Implemented as a single query using MERGE and WHEN (NOT) MATCHED THEN Note that SQLite returns undefined for created, no
matter if the row was created or updated. This is because SQLite
always runs INSERT OR IGNORE + UPDATE, in a single query, so there
is no way to know whether the row was inserted or not.
Update 07/2019 now with async/await
async function updateOrCreate (model, where, newItem) {
// First try to find the record
const foundItem = await model.findOne({where});
if (!foundItem) {
// Item not found, create a new one
const item = await model.create(newItem)
return {item, created: true};
}
// Found an item, update it
const item = await model.update(newItem, {where});
return {item, created: false};
}
I liked the idea of Ataik, but made it a little shorter:
function updateOrCreate (model, where, newItem) {
// First try to find the record
return model
.findOne({where: where})
.then(function (foundItem) {
if (!foundItem) {
// Item not found, create a new one
return model
.create(newItem)
.then(function (item) { return {item: item, created: true}; })
}
// Found an item, update it
return model
.update(newItem, {where: where})
.then(function (item) { return {item: item, created: false} }) ;
}
}
Usage:
updateOrCreate(models.NewsItem, {slug: 'sometitle1'}, {title: 'Hello World'})
.then(function(result) {
result.item; // the model
result.created; // bool, if a new item was created.
});
Optional: add error handling here, but I strongly recommend to chain all promises of one request and have one error handler at the end.
updateOrCreate(models.NewsItem, {slug: 'sometitle1'}, {title: 'Hello World'})
.then(..)
.catch(function(err){});
This might be an old question, but this is what I did:
var updateOrCreate = function (model, where, newItem, onCreate, onUpdate, onError) {
// First try to find the record
model.findOne({where: where}).then(function (foundItem) {
if (!foundItem) {
// Item not found, create a new one
model.create(newItem)
.then(onCreate)
.catch(onError);
} else {
// Found an item, update it
model.update(newItem, {where: where})
.then(onUpdate)
.catch(onError);
;
}
}).catch(onError);
}
updateOrCreate(
models.NewsItem, {title: 'sometitle1'}, {title: 'sometitle'},
function () {
console.log('created');
},
function () {
console.log('updated');
},
console.log);
User.upsert({ a: 'a', b: 'b', username: 'john' })
It will try to find record by hash in 1st param to update it, if it will not find it - then new record will be created
Here is example of usage in sequelize tests
it('works with upsert on id', function() {
return this.User.upsert({ id: 42, username: 'john' }).then(created => {
if (dialect === 'sqlite') {
expect(created).to.be.undefined;
} else {
expect(created).to.be.ok;
}
this.clock.tick(1000);
return this.User.upsert({ id: 42, username: 'doe' });
}).then(created => {
if (dialect === 'sqlite') {
expect(created).to.be.undefined;
} else {
expect(created).not.to.be.ok;
}
return this.User.findByPk(42);
}).then(user => {
expect(user.createdAt).to.be.ok;
expect(user.username).to.equal('doe');
expect(user.updatedAt).to.be.afterTime(user.createdAt);
});
});
Sound likes you want to wrap your Sequelize calls inside of an async.each.
This can be done with the custom event emitter.
Assuming your data is in a variable called data.
new Sequelize.Utils.CustomEventEmitter(function(emitter) {
if(data.id){
Model.update(data, {id: data.id })
.success(function(){
emitter.emit('success', data.id );
}).error(function(error){
emitter.emit('error', error );
});
} else {
Model.build(data).save().success(function(d){
emitter.emit('success', d.id );
}).error(function(error){
emitter.emit('error', error );
});
}
}).success(function(data_id){
// Your callback stuff here
}).error(function(error){
// error stuff here
}).run(); // kick off the queries
you can use findOrCreate and then update methods in sequelize. here is a sample with async.js
async.auto({
getInstance : function(cb) {
Model.findOrCreate({
attribute : value,
...
}).complete(function(err, result) {
if (err) {
cb(null, false);
} else {
cb(null, result);
}
});
},
updateInstance : ['getInstance', function(cb, result) {
if (!result || !result.getInstance) {
cb(null, false);
} else {
result.getInstance.updateAttributes({
attribute : value,
...
}, ['attribute', ...]).complete(function(err, result) {
if (err) {
cb(null, false);
} else {
cb(null, result);
}
});
}
}]
}, function(err, allResults) {
if (err || !allResults || !allResults.updateInstance) {
// job not done
} else {
// job done
});
});
Here is a simple example that either updates deviceID -> pushToken mapping or creates it:
var Promise = require('promise');
var PushToken = require("../models").PushToken;
var createOrUpdatePushToken = function (deviceID, pushToken) {
return new Promise(function (fulfill, reject) {
PushToken
.findOrCreate({
where: {
deviceID: deviceID
}, defaults: {
pushToken: pushToken
}
})
.spread(function (foundOrCreatedPushToken, created) {
if (created) {
fulfill(foundOrCreatedPushToken);
} else {
foundOrCreatedPushToken
.update({
pushToken: pushToken
})
.then(function (updatedPushToken) {
fulfill(updatedPushToken);
})
.catch(function (err) {
reject(err);
});
}
});
});
};
2022 update:
You can use the upsert function:
https://sequelize.org/api/v6/class/src/model.js~model#static-method-upsert
Insert or update a single row. An update will be executed if a row which matches the supplied values on either the primary key or a unique key is found. Note that the unique index must be defined in your sequelize model and not just in the table. Otherwise you may experience a unique constraint violation, because sequelize fails to identify the row that should be updated.
Implementation details:
MySQL - Implemented with ON DUPLICATE KEY UPDATE`
PostgreSQL - Implemented with ON CONFLICT DO UPDATE. If update data contains PK field, then PK is selected as the default conflict key.
Otherwise first unique constraint/index will be selected, which can satisfy conflict key requirements.
SQLite - Implemented with ON CONFLICT DO UPDATE
MSSQL - Implemented as a single query using MERGE and WHEN (NOT) MATCHED THEN
Note that Postgres/SQLite returns null for created, no matter if the row was created or updated