01 Setting Up Prisma Existing Database JAVASCRIPT A003

import Warning from 'components/Markdown/Warning' import QueryChooser from 'components/Markdown/QueryChooser' import Code from 'components/Markdown/Code' import Collapse from 'components/Markdown/Collapse'

export const meta = { title: 'Set up Prisma', position: 1, gettingStartedOrder: 2, gettingStartedTitle: 'Existing database', nextText: 'Great work! 👏 Move on to learn how you can extend your datamodel and make changes to your Prisma API.', technology: 'node', technologyOrder: 1, articleGroup: 'Set up Prisma', }

Goals

On this page, you will learn how to:

• Install the Prisma CLI
• Set up Prisma using Docker
• Introspect your existing database and derive a datamodel
• Use the datamodel to configure your Prisma API
• Generate a Prisma client
• Read and write data using the Prisma client

Using your existing database with Prisma currently only works when using PostgreSQL or MongoDB databases. It is not yet supported for MySQL.

Install the Prisma CLI

The Prisma CLI is used for various Prisma workflows. You can install it using Homebrew or NPM:

<Code languages={["Homebrew", "NPM"]}>

brew tap prisma/prisma
brew install prisma

npm install -g prisma

Install Docker

To use Prisma locally, you need to have Docker installed on your machine. If you don't have Docker yet, you can download the Docker Community Edition for your operating system here.

Set up Prisma

Run the following command to connect Prisma to your existing database:

prisma init hello-world

This launches an interactive wizard. Here's what you need to do:

1. Select Use existing database
2. Select your database, either PostgreSQL or MongoDB
3. Provide the connection details for your database (see below for more info)
4. Select the Prisma JavaScript client

• The host of your Postgres server, e.g. localhost. (When connecting to a local database, you might need to use host.docker.internal.)
• The port where your Postgres server listens, e.g. 5432.
• The name of your Postgres database.
• The name of your Postgres schema, e.g. public.
• The database user.
• The password for the database user.
• Whether your database server uses SSL, possible values are true and false.

• Your MongoDB connection string, e.g. http://user1:myPassword@localhost:27017/admin. Note that this must include the database credentials as well as the authSource database that's storing the credentials of your MongoDB admin user (by default it is often called admin). Learn more here.
• The name of your MongoDB database.

If you're using MongoDB Atlas, you can find your connection string by clicking the CONNECT-button on your cluster overview page. It looks similar to this: mongodb+srv://user:[email protected]/test?retryWrites=true.

Launch Prisma

To start Prisma and connect it to your database, run the following commands:

cd hello-world
docker-compose up -d

Prisma is now connected to your database and runs on http://localhost:4466.

Deploy the Prisma datamodel

You now have the minimal setup ready to deploy your Prisma datamodel. Run the following command (this does not change anything in your database):

prisma deploy

Launching the Prisma server may take a few minutes. In case the prisma deploy command fails, wait a few minutes and try again. Also run docker ps to ensure the Prisma Docker container is actually running.

Prepare Node application

Run the following command to create an empty Node script:

touch index.js

Next, initialize an empty NPM project in the current directory and install the required dependencies:

npm init -y
npm install --save prisma-client-lib

Read and write data using the Prisma client

The API operations of the Prisma client depend on the datamodel that was generated from the database introspection. The following sample queries assume there is a User type in the datamodel defined as follows:

type User {
  id: ID! @unique
  name: String!
}

If you don't have such a User type, you need to adjust the following code snippets with a type that matches your datamodel.

Add the following code in index.js:

const { prisma } = require('./generated/prisma-client')

// A `main` function so that we can use async/await
async function main() {

  // Create a new user called `Alice`
  const newUser = await prisma.createUser({ name: 'Alice' })
  console.log(`Created new user: ${newUser.name} (ID: ${newUser.id})`)

  // Read all users from the database and print them to the console
  const allUsers = await prisma.users()
  console.log(allUsers)
}

main().catch(e => console.error(e))

Execute the script with the following command:

node index.js

Whenever you run this script with that command, a new user record is created in the database (because of the call to createUser).

Feel free to play around with the Prisma client API and try out some of the following operations by adding the following code snippets to the file (at the end of the main function) and re-executing the script:

<QueryChooser titles={["Fetch single user", "Filter user list", "Update a user's name", "Delete user"]}>

const user = await prisma
  .user({ id: '__USER_ID__' })

const usersCalledAlice = await prisma
  .users({
    where: {
      name: 'Alice'
    }
  })

 const updatedUser = await prisma
  .updateUser({
    where: { id: '__USER_ID__' },
    data: { name: 'Bob' }
  })

 const deletedUser = await prisma
  .deleteUser({ id: '__USER_ID__' })

In some snippets, you need to replace the __USER__ID__ placeholder with the ID of an actual user.