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Connecting to a Database ​

To set a database connection for Remult, set the dataProvider property of the options argument of the remult Express middleware.

Here are examples of connecting to some commonly used back-end databases:

Remult can also be used to connect entities to local frontend databases.

Postgres ​

Using node-postgres (pg) only ​

Install node-postgres:

sh
npm i pg

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createPostgresConnection } from "remult/postgres"

const app = express()

const connectionString = "postgres://user:password@host:5432/database"

app.use(
  remultExpress({
    dataProvider:
      createPostgresConnection({
        connectionString // default: process.env["DATABASE_URL"]
      })
  })
)
  • If connectionString is not provided the DATABASE_URLenvironment will be used
Additional options
  • configuration - can be set to the pg.PoolConfig options object or to heroku. When set to heroku, it'll:
    • Use ssl, with the rejectUnauthorized:false flag as required by postgres on heroku
    • Disable ssl for non production environments (process.env["NODE_ENV"] !== "production"). To use ssl also for dev, set the sslInDev option to true.
  • sslInDev - see configuration:"heroku"

Using Knex.js ​

Install knex and node-postgres:

sh
npm i knex pg

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createKnexDataProvider } from "remult/remult-knex"

const app = express()

app.use(
  remultExpress({
    dataProvider: createKnexDataProvider({
      // Knex client configuration for Postgres
      client: "pg",
      connection: "postgres://user:password@host:5432/database"
    })
  })
)

MySQL ​

Install knex and mysql2:

sh
npm i knex mysql2

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createKnexDataProvider } from "remult/remult-knex"

const app = express()

app.use(
  remultExpress({
    dataProvider: createKnexDataProvider({
      // Knex client configuration for MySQL
      client: "mysql2",
      connection: {
        user: "your_database_user",
        password: "your_database_password",
        host: "127.0.0.1",
        database: "test"
      }
    })
  })
)

MongoDB ​

Install mongodb:

sh
npm i mongodb

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { MongoClient } from "mongodb"
import { MongoDataProvider } from "remult/remult-mongo"

const app = express()

app.use(
  remultExpress({
    dataProvider: async () => {
      const client = new MongoClient("mongodb://localhost:27017/local")
      await client.connect()
      return new MongoDataProvider(client.db("test"), client)
    }
  })
)

SQLite ​

Install knex and sqlite3:

sh
npm i knex sqlite3

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createKnexDataProvider } from "remult/remult-knex"

const app = express()

app.use(
  remultExpress({
    dataProvider: createKnexDataProvider({
      // Knex client configuration for SQLite
      client: "sqlite3",
      connection: {
        filename: "./mydb.sqlite"
      }
    })
  })
)

Microsoft SQL Server ​

Install knex and tedious:

sh
npm i knex tedious

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createKnexDataProvider } from "remult/remult-knex"

const app = express()

app.use(
  remultExpress({
    dataProvider: createKnexDataProvider({
      // Knex client configuration for MSSQL
      client: "mssql",
      connection: {
        server: "127.0.0.1",
        database: "test",
        user: "your_database_user",
        password: "your_database_password",
        options: {
          enableArithAbort: true,
          encrypt: false,
          instanceName: `sqlexpress`
        }
      }
    })
  })
)

Oracle ​

Install knex and oracledb:

sh
npm i knex oracledb

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { createKnexDataProvider } from "remult/remult-knex"

const app = express()

app.use(
  remultExpress({
    dataProvider: createKnexDataProvider({
      // Knex client configuration for Oracle
      client: "oracledb",
      connection: {
        user: "your_database_user",
        password: "your_database_password",
        connectString: "SERVER"
      }
    })
  })
)

JSON Files ​

Modify the API server's main module:

ts
// index.ts

import express from "express"
import { remultExpress } from "remult/remult-express"
import { JsonDataProvider } from "remult"
import { JsonEntityFileStorage } from "remult/server"

const app = express()

app.use(
  remultExpress({
    dataProvider: async () =>
      new JsonDataProvider(new JsonEntityFileStorage("./db"))
  })
)

Note

This is the default database used by Remult if no other dataProvider is set.

Frontend Databases ​

Although the common use case of Remult on the front end, is to call the backend using rest api, in some use cases using a local in browser database can be useful.

Local Storage ​

ts
import { JsonDataProvider, Remult } from "remult"
export const remultLocalStorage = new Remult(new JsonDataProvider(localStorage))

Session Storage ​

ts
import { JsonDataProvider, Remult } from "remult"
export const remultSessionStorage = new Remult(
  new JsonDataProvider(sessionStorage)
)

Web Sql ​

ts
import { Remult, SqlDatabase, WebSqlDataProvider } from "remult"
export const remultWebSql = new Remult(
  new SqlDatabase(new WebSqlDataProvider("db"))
)

In Memory object array ​

ts
import { Remult, InMemoryDataProvider } from "remult"
export const remult = new Remult(new InMemoryDataProvider())

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