feathers/docs/api/databases/knex.md

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SQL Databases

Support for SQL databases like PostgreSQL, MySQL, MariaDB, SQLite or MSSQL is provided in Feathers via the @feathersjs/knex database adapter which uses KnexJS. Knex is a fast and flexible query builder for SQL and supports many databases without the overhead of a full blown ORM like Sequelize. It still provides an intuitive syntax and more advanced tooling like migration support.

$ npm install --save @feathersjs/knex

The Knex adapter implements the common database adapter API and querying syntax.

API

service(options)

Returns a new service instance initialized with the given options.

const knex = require('knex')
const service = require('feathers-knex')

const db = knex({
  client: 'sqlite3',
  connection: {
    filename: './db.sqlite'
  }
})

// Create the schema
db.schema.createTable('messages', (table) => {
  table.increments('id')
  table.string('text')
})

app.use(
  '/messages',
  service({
    Model: db,
    name: 'messages'
  })
)
app.use('/messages', service({ Model, name, id, events, paginate }))

Options:

• Model (required) - The KnexJS database instance
• name (required) - The name of the table
• schema (optional) - The name of the schema table prefix (example: schema.table)
• id (optional, default: 'id') - The name of the id field property.
• events (optional) - A list of custom service events sent by this service
• paginate (optional) - A pagination object containing a default and max page size
• multi (optional) - Allow create with arrays and update and remove with id null to change multiple items. Can be true for all methods or an array of allowed methods (e.g. [ 'remove', 'create' ])
• whitelist (optional) - A list of additional query parameters to allow (e..g [ '$regex', '$geoNear' ]). Default is the supported operators

adapter.createQuery(query)

Returns a KnexJS query with the common filter criteria (without pagination) applied.

params.knex

When making a service method call, params can contain an knex property which allows to modify the options used to run the KnexJS query. See customizing the query for an example.

Example

Here's a complete example of a Feathers server with a messages SQLite service. We are using the Knex schema builder and SQLite as the database.

$ npm install @feathersjs/feathers @feathersjs/errors @feathersjs/express @feathersjs/socketio feathers-knex knex sqlite3

In app.js:

const feathers = require('@feathersjs/feathers')
const express = require('@feathersjs/express')
const socketio = require('@feathersjs/socketio')

const service = require('feathers-knex')
const knex = require('knex')

const db = knex({
  client: 'sqlite3',
  connection: {
    filename: './db.sqlite'
  }
})

// Create a feathers instance.
const app = express(feathers())
// Turn on JSON parser for REST services
app.use(express.json())
// Turn on URL-encoded parser for REST services
app.use(express.urlencoded({ extended: true }))
// Enable REST services
app.configure(express.rest())
// Enable Socket.io services
app.configure(socketio())
// Create Knex Feathers service with a default page size of 2 items
// and a maximum size of 4
app.use(
  '/messages',
  service({
    Model: db,
    name: 'messages',
    paginate: {
      default: 2,
      max: 4
    }
  })
)
app.use(express.errorHandler())

// Clean up our data. This is optional and is here
// because of our integration tests
db.schema
  .dropTableIfExists('messages')
  .then(() => {
    console.log('Dropped messages table')

    // Initialize your table
    return db.schema.createTable('messages', (table) => {
      console.log('Creating messages table')
      table.increments('id')
      table.string('text')
    })
  })
  .then(() => {
    // Create a dummy Message
    app
      .service('messages')
      .create({
        text: 'Message created on server'
      })
      .then((message) => console.log('Created message', message))
  })

// Start the server.
const port = 3030

app.listen(port, () => {
  console.log(`Feathers server listening on port ${port}`)
})

Run the example with node app and go to localhost:3030/messages

Querying

In addition to the common querying mechanism, this adapter also supports:

$and

Find all records that match all of the given criteria. The following query retrieves all messages that have foo and bar attributes as true.

app.service('messages').find({
  query: {
    $and: [{ foo: true }, { bar: true }]
  }
})

Through the REST API:

/messages?$and[][foo]=true&$and[][bar]=true

$like

Find all records where the value matches the given string pattern. The following query retrieves all messages that start with Hello:

app.service('messages').find({
  query: {
    text: {
      $like: 'Hello%'
    }
  }
})

Through the REST API:

/messages?text[$like]=Hello%

$notlike

The opposite of $like; resulting in an SQL condition similar to this: WHERE some_field NOT LIKE 'X'

app.service('messages').find({
  query: {
    text: {
      $notlike: '%bar'
    }
  }
})

Through the REST API:

/messages?text[$notlike]=%bar

$ilike

For PostgreSQL only, the keywork $ilike can be used instead of $like to make the match case insensitive. The following query retrieves all messages that start with hello (case insensitive):

app.service('messages').find({
  query: {
    text: {
      $ilike: 'hello%'
    }
  }
})

Through the REST API:

/messages?text[$ilike]=hello%

Transaction Support

The Knex adapter comes with three hooks that allows to run service method calls in a transaction. They can be used as application wide (app.hooks.js) hooks or per service like this:

// A common hooks file
const { hooks } = require('feathers-knex')

const { transaction } = hooks

module.exports = {
  before: {
    all: [transaction.start()],
    find: [],
    get: [],
    create: [],
    update: [],
    patch: [],
    remove: []
  },

  after: {
    all: [transaction.end()],
    find: [],
    get: [],
    create: [],
    update: [],
    patch: [],
    remove: []
  },

  error: {
    all: [transaction.rollback()],
    find: [],
    get: [],
    create: [],
    update: [],
    patch: [],
    remove: []
  }
}

To use the transactions feature, you must ensure that the three hooks (start, end and rollback) are being used.

At the start of any request, a new transaction will be started. All the changes made during the request to the services that are using the feathers-knex will use the transaction. At the end of the request, if sucessful, the changes will be commited. If an error occurs, the changes will be forfeit, all the creates, patches, updates and deletes are not going to be commited.

The object that contains transaction is stored in the params.transaction of each request.

Important: If you call another Knex service within a hook and want to share the transaction you will have to pass context.params.transaction in the parameters of the service call.

Customizing the query

In a find call, params.knex can be passed a KnexJS query (without pagination) to customize the find results.

Combined with .createQuery({ query: {...} }), which returns a new KnexJS query with the common filter criteria applied, this can be used to create more complex queries. The best way to customize the query is in a before hook for find.

app.service('messages').hooks({
  before: {
    find(context) {
      const query = context.service.createQuery(context.params)

      // do something with query here
      query.orderBy('name', 'desc')

      context.params.knex = query
      return context
    }
  }
})

Configuring migrations

For using knex's migration CLI, we need to make the configuration available by the CLI. We can do that by providing a knexfile.js (OR knexfile.ts when using TypeScript) in the root folder with the following contents:

knexfile.js

const app = require('./src/app')
module.exports = app.get('postgres')

OR

knexfile.ts

import app from './src/app'
module.exports = app.get('postgres')

You will need to replace the postgres part with the adapter you are using. You will also need to add a migrations key to your feathersjs config under your database adapter. Optionally, add a seeds key if you will be using seeds.

// src/config/default.json
...
  "postgres": {
    "client": "pg",
    "connection": "postgres://user:password@localhost:5432/database",
    "migrations": {
      "tableName": "knex_migrations"
    },
    "seeds": {
      "directory": "../src/seeds"
    }
  }

Then, by running: knex migrate:make create-users, a migrations directory will be created, with the new migration.

Error handling

As of version 4.0.0 feathers-knex only throws Feathers Errors with the message. On the server, the original error can be retrieved through a secure symbol via error[require('feathers-knex').ERROR]

const { ERROR } = require('feathers-knex')

try {
  await knexService.doSomething()
} catch (error) {
  // error is a FeathersError with just the message
  // Safely retrieve the Knex error
  const knexError = error[ERROR]
}

Waiting for transactions to complete

Sometimes it can be important to know when the transaction has been completed (committed or rolled back). For example, we might want to wait for transaction to complete before we send out any realtime events. This can be done by awaiting on the transaction.committed promise which will always resolve to either true in case the transaction has been committed, or false in case the transaction has been rejected.

app.service('messages').publish((data, context) => {
  const { transaction } = context.params

  if (transaction) {
    const success = await transaction.committed
    if (!success) {
      return []
    }
  }

  return app.channel(`rooms/${data.roomId}`)
})

This also works with nested service calls and nested transactions. For example, if a service calls transaction.start() and passes the transaction param to a nested service call, which also calls transaction.start() in it's own hooks, they will share the top most committed promise that will resolve once all of the transactions have succesfully committed.