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
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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());
});
What is the idiomatic way for doing an 'insert if not exists'?
Can this be done without transactions?
Try this:
with upsert creates a record if it doesn't exists, unless it updates
var OrientDB = require('orientjs');
var server = OrientDB({
host: 'localhost',
port: 2424,
username: 'root',
password: 'root'
});
var db = server.use({
name: 'GratefulDeadConcerts',
username: 'root',
password: 'root'
})
db.query('UPDATE V SET id = 23 UPSERT WHERE id = 23')
.then(function (response) {
console.log(response);
});
server.close();
Hope it helps.
Regards
You can use this code for example
db.query('select from v where rid = 23')
.then(function (record) {
if(record.length==0){
db.query('insert into v(rid) values (23)');
}
});
Hope it helps.
If the data is quite small (that you can hold in memory in the server), you can do 1 get call to fetch all the data and do a batch insert only for those which are not already there.
If your creation data is very huge (that exceeds the runtime memory), you will have to follow Alessandro's method (which will be slow because for each insertion you'll have to check).
Per the docs, StrongLoop doesn't support running custom sql statements.
https://docs.strongloop.com/display/public/LB/Executing+native+SQL
How anyone thinks you can build an enterprise app with just simple joins is beyond me, but I did find this post which says you can do it:
Execute raw query on MySQL Loopback Connector
But this is for MySql. When I try it with Postgres I get the error: "Invalid value for argument 'byId' of type 'object': 0. Received type was converted to number." And it returns no data. Here is my code:
module.exports = function(account) {
account.byId = function(byId, cb){
var ds=account.dataSource;
var sql = "SELECT * FROM account where id > ?";
ds.connector.execute(sql, [Number(byId)], function(err, accounts) {
if (err) console.error(err);
console.info(accounts);
cb(err, accounts);
});
};
account.remoteMethod(
'byId',
{
http: {verb: 'get'},
description: "Get accounts greater than id",
accepts: {arg: 'byId', type: 'integer'},
returns: {arg: 'data', type: ['account'], root: true}
}
);
};
For the part [Number(byId)], I've also tried [byId] and just byId. Nothing works.
Any ideas? So far I really like StrongLoop, but it looks like the Postgresql connector is not ready for production. I'll be doing a prototype with Sails next if this doesn't work. :-(
Here's the thing arg is of type 'integer' which is not a valid Loopback Type. Use `Number instead. Check the corrected code below:
module.exports = function(account) {
account.byId = function(byId, cb){
var ds = account.dataSource;
var sql = "SELECT * FROM account WHERE id > $1";
ds.connector.execute(sql, byId, function(err, accounts) {
if (err) console.error(err);
console.info(accounts);
cb(err, accounts);
});
};
account.remoteMethod(
'byId',
{
http: {verb: 'get'},
description: "Get accounts greater than id",
accepts: {arg: 'byId', type: 'Number'},
returns: {arg: 'data', type: ['account'], root: true} //here 'account' will be treated as 'Object'.
}
);
};
Note: MySQL's prepared statements natively use ? as the parameter placeholder, but PostgreSQL uses $1, $2 etc.
Hope this works for you. Else try with [byId] instead of byId as per the docs.
I'm using an OrientDB graph database, I have two vertexes Room and Participant, I have created a few edges between Room and Participant records and I want to execute the following command using orientjs driver:
select from (traverse out() from (select from room where name='room test 1')) where #class='Participant'
Updated
I have in mind to use something like this:
db.let('firstSelect', function(s){
s.select().from('room').where({name:'room test 1'});
}).let('traverse', function(s){
s.traverse('out()').from('$firstSelect').while('$depth<=1');
}).let('finalSelect', function(s){
s.select().from('$traverse').where({'#class':'Participant'});
}).commit()
.return('$finalSelect')
.all()
.then(function(participants){
console.log(participants);
})
In the future I will put this code in a function with some parametters
You could use the db.query API:
var OrientDB = require('orientjs');
var server = OrientDB({
host: 'localhost',
port: 2424,
username: 'root',
password: 'root'
});
var db = server.use({
name: 'OrientJStest',
username: 'root',
password: 'root'
});
db.query('select from (traverse out() from (select from room where name="room test 1")) where #class = :inputClass', {
params: {
inputClass: "Participant"
},
limit: -1
}).then(function (results) {
console.log('Vertexes found: ');
console.log();
console.log(results);
});
Hope it helps
I would like to pars url after form submit.
I have simple form:
form(method='post', action='/recipe/create')
hr
div
div.input.text
label(for='recipeTitle') Tytuł przepisu:
input(type='text', name='recipeTitle', id='recipeTitle')
div.input.text
label(for='photoFileName') Nazwa zdjęcia:
input(type='text', name='photoFileName', id='photoFileName')
After submit this code is executed.
exports.create = function(req, res){
var url = require('url');
var url_parts = url.parse(req.url, true);
console.log(url_parts);
My question is why console shows empty query
{ protocol: null,
slashes: null,
auth: null,
host: null,
port: null,
hostname: null,
hash: null,
search: '',
query: {},
pathname: '/recipe/create',
path: '/recipe/create',
href: '/recipe/create' }
This happens because you're posting to an URL which doesn't have a query string - /recipe/create.
Also, you seem to be using Express, which will give you the current query string already parsed:
// GET /search?q=tobi+ferret
req.query.q
// => "tobi ferret"
// GET /shoes?order=desc&shoe[color]=blue&shoe[type]=converse
req.query.order
// => "desc"
req.query.shoe.color
// => "blue"
req.query.shoe.type
// => "converse"
Reference