01 Setting Up Prisma Existing Database GO G003 - Prisma1

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: 'go', technologyOrder: 4, 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.

</Warning>

Install the Prisma CLI

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

bash

brew tap prisma/prisma
brew install prisma

bash

npm install -g prisma

</Code>

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:

bash

prisma init hello-world

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

Select Use existing database
Select your database, either PostgreSQL or MongoDB
Provide the connection details for your database (see below for more info)
Select the Prisma Go 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.

</Collapse> <Collapse title="Connection details for MongoDB">

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.

</Collapse>

Launch Prisma

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

bash

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):

bash

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.

</Warning>

Prepare Go application

bash

touch index.go

You'll be using dep for dependency management in this tutorial. Run the following command to create the required setup:

bash

dep init

Great, you're now ready to write some code and talk to your database programmatically!

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:

graphql

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.go:

package main

import (
	"context"
	"fmt"
	prisma "hello-world/generated/prisma-client"
)

func main() {
	client := prisma.New(nil)
	ctx := context.TODO()

	// Create a new user
	name := "Alice"
	newUser, err := client.CreateUser(prisma.UserCreateInput{
		Name: name,
	}).Exec(ctx)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Created new user: %+v\\n", newUser)

  // Fetch all users
	users, err := client.Users(nil).Exec(ctx)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%+v\\n", users)
}

Before executing the script, you need to ensure all dependencies are available. Run the following command:

bash

dep ensure

Now execute the script with the following command:

bash

go run index.go

Whenever you run the 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:

id := "__USER_ID__"
userById, err := client.User(prisma.UserWhereUniqueInput{
  ID: &id,
}).Exec(ctx)

filter := "Alice"
posts, err := client.Users(&prisma.UsersParams{
  Where: &prisma.UserWhereInput{
    Name: &filter,
  },
}).Exec(ctx)

id := "__USER_ID__"
newName := "Bob"
updatedUser, err := client.UpdateUser(prisma.UserUpdateParams{
  Where: prisma.UserWhereUniqueInput{
    ID: &id,
  },
  Data: prisma.UserUpdateInput{
    Name: &newName,
  },
}).Exec(ctx)

id := "__USER_ID__"
deletedUser, err := client.DeleteUser(prisma.UserWhereUniqueInput{
  ID: &id,
}).Exec(ctx)

</QueryChooser>

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