I am learning to use mongoDB AND ExpressJS by building a Rest API that I would use with ReactJS.
I have always chosen MySQL for the management of my database, but the mongoDB database is not relational and it is still difficult for me to understand.
An example of what I want to do
Let's say that I have created a blog and want to get all the articles from a user logged in with an account.
All these operations are managed with a REST API and MongoDB.
How to create a OneToMany relationship between articles and a user.
With MySQL I just had to specify a user_id key for each article in an article table.
But with mongoDB how to create this and especially for a user who is logged in with an account, so that only a logged in user can view his articles.
EDIT
I have tried something, it works but I don't know if it's the right approach.
Context:
I made a REST API with NodeJS and ExpressJS.
The API will allow a user to organize their applications to facilitate the search for a job.
A user must create an account and log in to take advantage of all of the application's features, so no information is publicly available.
For registration and authentication of a user, I use PassportJS, mongoConnect and ExpressSession
To start, the User model of mongoDB
const userSchema = mongoose.Schema({
name: {
type:String
},
email: {
type:String,
required:true,
unique:true
},
email_is_verified: {
type:Boolean,
default:false
},
password: {
type:String,
},
referral_code : {
type:String,
default: function() {
let hash = 0;
for(let i=0; i < this.email.length; i++){
hash = this.email.charCodeAt(i) + ((hash << 5) - hash);
}
let res = (hash & 0x00ffffff).toString(16).toUpperCase();
return "00000".substring(0, 6 - res.length) + res;
}
},
referred_by : {
type: String,
default:null
},
third_party_auth: [ThirdPartyProviderSchema],
date: {
type:Date,
default: Date.now
}
},
{ strict: false }
);
module.exports = mongoose.model('Users', userSchema);
The Apply model represents an apply for a job, for now there is only the title.
To create the OneToMany relationship, I add a User field which refers to my User model
Function to retrieve all applies, so I retrieve the user id of the session.
const applySchema = mongoose.Schema({
title: { type:String, required:true },
user: {
type: mongoose.Schema.Types.ObjectId,
ref: "User"
}
})
module.exports = mongoose.model('Apply', applySchema);
I created a controller for the management of a user's applies
exports.getAllApplies = (req, res, next) => {
res.locals.currentUser = req.user;
const userId = res.locals.currentUser.id
Apply.find({ user:userId })
.then(applies => res.status(200).json({ message:'success',
applies:applies }))
.catch(error => res.status(400).json({ error:error, message: 'Failed'}))
}
Function allowing to consult an apply
exports.getOneApply = (req, res, next) => {
res.locals.currentUser = req.user;
const userId = res.locals.currentUser.id
Apply.findOne({ _id:req.params.id, user:userId })
.then(apply => res.status(200).json({ message: `Apply with id
${apply._id} success`, apply:apply}))
.catch(error => res.status(500).json({ error:error, message:'Failed'}))
}
The routes of my api, I add an auth middleware to allow requests only for a user with a token
const express = require('express');
const router = express.Router();
const auth = require('../middleware/auth');
const applyCtrl = require('../controllers/apply');
router.get('/', auth, applyCtrl.getAllApplies);
router.get('/:id', auth, applyCtrl.getOneApply);
module.exports = router;
I apologize for the length of the post, if you have any questions, I would be happy to answer them.
Thank you in advance for your help and your answers.
GraphQL has mutations, Postgres has INSERT; GraphQL has queries, Postgres has SELECT's; etc., etc.. I haven't found an example showing how you could use both in a project, for example passing all the queries from front end (React, Relay) in GraphQL, but to a actually store the data in Postgres.
Does anyone know what Facebook is using as DB and how it's connected with GraphQL?
Is the only option of storing data in Postgres right now to build custom "adapters" that take the GraphQL query and convert it into SQL?
GraphQL is database agnostic, so you can use whatever you normally use to interact with the database, and use the query or mutation's resolve method to call a function you've defined that will get/add something to the database.
Without Relay
Here is an example of a mutation using the promise-based Knex SQL query builder, first without Relay to get a feel for the concept. I'm going to assume that you have created a userType in your GraphQL schema that has three fields: id, username, and created: all required, and that you have a getUser function already defined which queries the database and returns a user object. In the database I also have a password column, but since I don't want that queried I leave it out of my userType.
// db.js
// take a user object and use knex to add it to the database, then return the newly
// created user from the db.
const addUser = (user) => (
knex('users')
.returning('id') // returns [id]
.insert({
username: user.username,
password: yourPasswordHashFunction(user.password),
created: Math.floor(Date.now() / 1000), // Unix time in seconds
})
.then((id) => (getUser(id[0])))
.catch((error) => (
console.log(error)
))
);
// schema.js
// the resolve function receives the query inputs as args, then you can call
// your addUser function using them
const mutationType = new GraphQLObjectType({
name: 'Mutation',
description: 'Functions to add things to the database.',
fields: () => ({
addUser: {
type: userType,
args: {
username: {
type: new GraphQLNonNull(GraphQLString),
},
password: {
type: new GraphQLNonNull(GraphQLString),
},
},
resolve: (_, args) => (
addUser({
username: args.username,
password: args.password,
})
),
},
}),
});
Since Postgres creates the id for me and I calculate the created timestamp, I don't need them in my mutation query.
The Relay Way
Using the helpers in graphql-relay and sticking pretty close to the Relay Starter Kit helped me, because it was a lot to take in all at once. Relay requires you to set up your schema in a specific way so that it can work properly, but the idea is the same: use your functions to fetch from or add to the database in the resolve methods.
One important caveat is that the Relay way expects that the object returned from getUser is an instance of a class User, so you'll have to modify getUser to accommodate that.
The final example using Relay (fromGlobalId, globalIdField, mutationWithClientMutationId, and nodeDefinitions are all from graphql-relay):
/**
* We get the node interface and field from the Relay library.
*
* The first method defines the way we resolve an ID to its object.
* The second defines the way we resolve an object to its GraphQL type.
*
* All your types will implement this nodeInterface
*/
const { nodeInterface, nodeField } = nodeDefinitions(
(globalId) => {
const { type, id } = fromGlobalId(globalId);
if (type === 'User') {
return getUser(id);
}
return null;
},
(obj) => {
if (obj instanceof User) {
return userType;
}
return null;
}
);
// a globalId is just a base64 encoding of the database id and the type
const userType = new GraphQLObjectType({
name: 'User',
description: 'A user.',
fields: () => ({
id: globalIdField('User'),
username: {
type: new GraphQLNonNull(GraphQLString),
description: 'The username the user has selected.',
},
created: {
type: GraphQLInt,
description: 'The Unix timestamp in seconds of when the user was created.',
},
}),
interfaces: [nodeInterface],
});
// The "payload" is the data that will be returned from the mutation
const userMutation = mutationWithClientMutationId({
name: 'AddUser',
inputFields: {
username: {
type: GraphQLString,
},
password: {
type: new GraphQLNonNull(GraphQLString),
},
},
outputFields: {
user: {
type: userType,
resolve: (payload) => getUser(payload.userId),
},
},
mutateAndGetPayload: ({ username, password }) =>
addUser(
{ username, password }
).then((user) => ({ userId: user.id })), // passed to resolve in outputFields
});
const mutationType = new GraphQLObjectType({
name: 'Mutation',
description: 'Functions to add things to the database.',
fields: () => ({
addUser: userMutation,
}),
});
const queryType = new GraphQLObjectType({
name: 'Query',
fields: () => ({
node: nodeField,
user: {
type: userType,
args: {
id: {
description: 'ID number of the user.',
type: new GraphQLNonNull(GraphQLID),
},
},
resolve: (root, args) => getUser(args.id),
},
}),
});
We address this problem in Join Monster, a library we recently open-sourced to automatically translate GraphQL queries to SQL based on your schema definitions.
This GraphQL Starter Kit can be used for experimenting with GraphQL.js and PostgreSQL:
https://github.com/kriasoft/graphql-starter-kit - Node.js, GraphQL.js, PostgreSQL, Babel, Flow
(disclaimer: I'm the author)
Have a look at graphql-sequelize for how to work with Postgres.
For mutations (create/update/delete) you can look at the examples in the relay repo for instance.
Postgraphile https://www.graphile.org/postgraphile/ is Open Source
Rapidly build highly customisable, lightning-fast GraphQL APIs
PostGraphile is an open-source tool to help you rapidly design and
serve a high-performance, secure, client-facing GraphQL API backed
primarily by your PostgreSQL database. Delight your customers with
incredible performance whilst maintaining full control over your data
and your database. Use our powerful plugin system to customise every
facet of your GraphQL API to your liking.
You can use an ORM like sequelize if you're using Javascript or Typeorm if you're using Typescript
Probably FB using mongodb or nosql in backend. I've recently read a blog entry which explain how to connect to mongodb. Basically, you need to build a graph model to match the data you already have in your DB. Then write resolve, reject function to tell GQL how to behave when posting a query request.
See https://www.compose.io/articles/using-graphql-with-mongodb/
Have a look at SequelizeJS which is a promise based ORM that can work with a number of dialects; PostgreSQL, MySQL, SQLite and MSSQL
The below code is pulled right from its example
const Sequelize = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password', {
host: 'localhost',
dialect: 'mysql'|'sqlite'|'postgres'|'mssql',
pool: {
max: 5,
min: 0,
acquire: 30000,
idle: 10000
},
// SQLite only
storage: 'path/to/database.sqlite',
// http://docs.sequelizejs.com/manual/tutorial/querying.html#operators
operatorsAliases: false
});
const User = sequelize.define('user', {
username: Sequelize.STRING,
birthday: Sequelize.DATE
});
sequelize.sync()
.then(() => User.create({
username: 'janedoe',
birthday: new Date(1980, 6, 20)
}))
.then(jane => {
console.log(jane.toJSON());
});
I want to change my Rest-API validation to node simple schema for schema definition and collection2#core for schema validation.
I want to use the Person schema to validate the data provided by the users.
Schemas = {};
Schemas.Person = new SimpleSchema({
name: {
type: String,
label: "Person's Name",
unique: true,
max: 200
},
surname: {
type: String,
unique: true,
label: "person's surname"
},
};
validData = API.utility.validate(data, Schemas.Person });
API: {
utility: {
validate: function(data, schema) {
return "The SimpleSchema Validation";
}
}
};
This case is described in the simpl-schema documentation
With your schema definition you can just do:
Schemas.person.validate(data);
If right after that you want to look at the result or the errors:
Schemas.person.isValid();
Schemas.person.validationErrors();
I'm using several one to many associations in Sails.JS that look like the following:
User
email: {
type: 'string',
required: true,
unique: true
},
projects: {
collection: 'project',
via: 'user'
}
Project
name: {
type: 'string',
required: true,
minLength: 3,
maxLength: 50
},
user: {
model: 'user',
required: true
},
sites: {
collection: 'site',
via: 'project'
}
Site
project: {
model: 'project',
required: true
},
name: {
type: 'string',
required: true
}
Now when I fire off a POST request to /project it creates the project fine, and specifying the param 'user' (taken from the session) associates the project with that particular user.
The same goes for when I create a new site. However, I appear to be able to specify any number for the param 'project', even if that particular project ID doesn't exist. Really it should fail the validation if the project doesn't exist and not create the site. I thought it'd look up the association with project and check that the project ID specified is valid?
Also, I only want to be able to create a site that is associated with a project that belongs to the current user. How would I go about doing this?
Thanks in advance.
I'm not sure if it's a bug or intended behavior with your non-existent project ID association, but one work-around is to have a beforeCreate hook in your models to verify that the project ID exists:
// In your Site model
beforeCreate: function(values, next) {
...
var projectID = values['project'];
Project.findOne(projectID, function (err, project) {
if (err || !project) return next("some error message");
return next();
});
}
You can also do a check in the beforeCreate hook for your second question:
// In your Site model
beforeCreate: function(values, next) {
...
var projectID = values['project'];
Project.findOne(projectID).populate('user').exec(function (err, project) {
if (err || !project) return next("some error message");
if (project.user.id != values['userID']) return next("some other error message");
return next();
});
}
Note that you'll have to pass 'userID' as a param into the params for creating a Site instance.
I'm new to tastypie and am trying to post to the following model:
class UserScore(models.Model):
"""
User Scores, used to categorise users
"""
user = models.OneToOneField(User)
category = models.ForeignKey(Category)
score = models.IntegerField()
and this is my api:
class UserScoreResource(ModelResource):
category = fields.ForeignKey(CategoryResource, 'category')
user = fields.OneToOneField(UserResource, 'user')
class Meta:
queryset = UserScore.objects.all()
resource_name = 'score'
authorization=Authorization()
allowed_methods = ['post', 'put', 'get']
In my unit tests I'm trying to run the following:
def test_no_post_to_userscore(self):
post_data = {
'user': {'resource_uri':'/api/v1/user/0/'},
'category': {'resource_uri':'/api/v1/category/0/'},
'score': 50,
}
print response.status_code
But am receiving a 500 error. Any help greatly appreciated!
Solved - bad syntax. Long day
Thanks