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 would like to use sails with sails-disk, migrate: drop so that whenever I run testcase I can have a new database with the following configuration on local.js. I am fine with sails lift. However, once I update migrate: drop or adapter to sails-disk or sails-memory. I am not able to sails lift from bootstrap and under server I can not even get configuration information. the sails lift just handling. without any detail message.
#config.js
module.exports = {
models: {
connection: 'testing',
migrate: 'drop',
},
connections: {
testing: {
adapter: 'sails-disk',
host: '127.0.0.1',
user: 'test',
password: 'test',
database: 'db',
},
},
};
#bootstrap.test.js
const TestConfig = require('./config/local');
before((done) => {
// Increase the Mocha timeout so that Sails has enough time to lift.
Sails.lift({
connections: TestConfig.connections,
models: TestConfig.models,
}, function(err) {
if (err) { return done(err); }
return done(err, server);
});
});
#error message
after adding more debug information before return I can not get config information
1) "before all" hook
0 passing (3s)
1 failing
1) "before all" hook:
Uncaught TypeError: Cannot read property 'config' of undefined
at async.series (test/bootstrap.test.js:29:26)
at node_modules/async/dist/async.js:3888:9
at node_modules/async/dist/async.js:473:16
at replenish (node_modules/async/dist/async.js:1006:25)
at node_modules/async/dist/async.js:1016:9
at eachOfLimit (node_modules/async/dist/async.js:1041:24)
at node_modules/async/dist/async.js:1046:16
at _parallel (node_modules/async/dist/async.js:3879:5)
at Object.series (node_modules/async/dist/async.js:4735:5)
at Sails.lift (test/bootstrap.test.js:19:11)
Since you're not providing any error message, I just can guessing that your config is wrong.
You have to name each connection and tell which one you want to use.
module.exports = {
models: {
migrate: 'drop',
connection : 'testing',
},
connections: {
testing : {
adapter: 'sails-disk',
host: '127.0.0.1',
user: 'user',
password: 'password',
database: 'db',
}
},
},
I created a migration file to add a column as an up and then delete it under down.
Here's the migration file code:
module.exports = {
up: (queryInterface, Sequelize) =>
queryInterface.addColumn('Books', 'Rating', {
allowNull: false,
type: Sequelize.ENUM('like', 'dislike'),
}),
down: (queryInterface, Sequelize) => {
queryInterface.removeColumn('Books', 'Rating');
},
};
When I ran it for the first time using db:migrate, it successfully added the column but when I did a db:migrate:undo:all and then ran the migrations again, it threw me an error sqying
======= 20180211100937-AddedRatingIntoBooks: migrating
======= 2018-02-11 15:42:46.076 IST
[64531] ERROR: type "enum_Books_Rating" already exists 2018-02-11 15:42:46.076 IST
[64531] STATEMENT: CREATE TYPE "public"."enum_Books_Rating" AS ENUM('like', 'dislike');
ALTER TABLE "public"."Boo ks" ADD COLUMN "Rating" "public"."enum_Books_Rating";
ERROR: type "enum_Books_Rating" already exists
The issue is still live here.
Sequelize creates TYPES for each of the enum you define, which you can find here
The name of the ENUM type is the concatenation of "enum", the table name, and the column name in snake casing. (enum_Books_Rating here)
To create migrations for ENUM, you have to modify your down function like so:
module.exports = {
up: (queryInterface, Sequelize) =>
queryInterface.addColumn('Books', 'Rating', {
allowNull: false,
type: Sequelize.ENUM('like', 'dislike')
}),
down: (queryInterface, Sequelize) =>
queryInterface.removeColumn('Books', 'Rating')
.then(() => queryInterface.sequelize.query('DROP TYPE "enum_Books_Rating";'));
};
Hope this helps.
I have a sails app working against a legacy database (MySQL) and I would like to perform integration tests. I am using fixtures to load data into a separate test database using barrels. When I run my tests I get an error:
[Error (E_UNKNOWN) Encountered an unexpected error] Details: Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')' at line 1
Interview.js api/models/Interview.js:
module.exports = {
tableName: 'interview',
attributes: {
interviewId: {
type: 'integer',
columnName: 'interview_id',
primaryKey: true,
unique: true
},
...
}
};
interview.json tests/fixtures:
[
{
"interviewId": 1,
"title": "some string",
"createdDate": "2015-11-23T09:09:03.000Z",
"lastModified": "2015-11-23T09:09:03.000Z"
},
{...}
]
test environment config/env/test.js :
models: {
connection: 'test',
migrate: 'drop',
autoPK: false,
autoCreatedAt: false,
autoUpdatedAt: false
}
The problem seems to lie in defining a primary key in the schema rather than letting sails create one automatically. If I remove the interviewId field from the model and set autoPK: true it works. But this does not accurately represent my data structure.
App info:
sails#0.11.2 sails-mysql#0.11.2 waterline#0.10.27 barrels#1.6.2 node v0.12.7
Many thanks,
Andy
I am not able to lift sails version 0.9.9 with postgresql version 0.9.7
Here is the error message that I get
debug: Lowering sails...
/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:285
if(self._schema[key].type === 'text') caseSensitive = false;
^
TypeError: Cannot read property 'type' of undefined
at Object.sql.and (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:285:27)
at /home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:256:19
at Array.forEach (native)
at [object Object].Query.where (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:195:24)
at /home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:119:14
at Array.forEach (native)
at [object Object].Query._build (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:115:32)
at [object Object].Query.find (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/query.js:35:21)
at __FIND__ (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/adapter.js:362:40)
at after (/home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/adapter.js:506:7)
at /home/mandeep/iqr/thirstt/node_modules/sails-postgresql/lib/adapter.js:492:7
It was running fine earlier. Not sure what went wrong. I have tried removing node_modules directory and doing a npm install after npm cache clear but still keep getting this error. I cannot upgrade to sails version 0.10 since its quite a big project and upgrade will be a really big effort. How can I fix this issue in the same version ? Any help will be appreciated.
I figured out the issue. Seems like a sails-postgresql issue to me. I was doing a findOne on a model in config/bootstrap.js and it was failing when there was no record in that table
Here is the part where it fails ( node_modules/sails-postgresql/lib/query.js ):
Query.prototype.operators = function() {
var self = this;
var sql = {
and: function(key, options, comparator) {
var caseSensitive = true;
// Check if key is a string
if(self._schema[key].type === 'text') caseSensitive = false;
processCriteria.call(self, key, options, '=', caseSensitive);
self._query += (comparator || ' AND ');
},
I logged the value of self. When data exists in the table that I queried in bootstrap.js, self looks like this
{ _values:
[ 2,
1,
'Mon, 29 Sep 2014 09:46:08 GMT',
'Thu, 06 Nov 2014 08:24:34 GMT' ],
_paramCount: 5,
_query: 'UPDATE "cache" SET "val" = $1, "id" = $2, "createdAt" = $3, "updatedAt" = $4 ',
_schema:
{ val: { type: 'integer' },
id: { type: 'integer', primaryKey: true, autoIncrement: true },
createdAt: { type: 'timestamp with time zone' },
updatedAt: { type: 'timestamp with time zone' } }
}
However, when there is no data in the table, then self looks like this
{ _values: [],
_paramCount: 1,
_query: 'SELECT * FROM "cache" ',
_schema: true
}
And then it accesses self._schema[key].type which raises the error since self._schema is not an object in this case. On inserting data to the table, things got fixed but I believe it's a logical bug in sails-postgresql since it should work fine even if there is no data in the table.