Prisma: How to Clear the Database

When working with a website that utilizes Prisma, it is often necessary to clear the database to remove test data. In this blog post, we will explore different methods to effectively clear the database using Prisma.

Deleting All Items

To clear all items in the database, you can use the following code snippet:

await prisma.user.deleteMany({})

This will delete all the user entries in the database, effectively clearing the data.

Iterating and Deleting Items

If you need to iterate over the items in the database for further processing before deletion, you can follow this approach:

const users = await prisma.user.findMany({})

const deleteUser = async (user) => {
  return await prisma.user.delete({
    where: { id: user.id }
  })
}

const deleteUsers = async () => {
  users.map((user) => deleteUser(user))
}

deleteUsers()

In this example, the deleteUser function is used to delete individual user entries. You can perform any desired processing within this function. The deleteUsers function iterates over the users and deletes them one by one.

Handling Relation Between Tables

In cases where there are relations between tables, additional steps may be required to properly clear the database. Let’s consider an example with two tables: tweets and users, where a tweet is associated with a user. To clear the database with this relation, follow these steps:

const clearData = async (prisma) => {
  const users = await prisma.user.findMany({})
  const tweets = await prisma.tweet.findMany({})

  const deleteUser = async (user) => {
    return await prisma.user.delete({
      where: { id: user.id }
    })
  }

  const deleteTweet = async (tweet) => {
    return await prisma.tweet.delete({
      where: { id: tweet.id }
    })
  }

  const deleteTweets = async () => {
    return Promise.all(tweets.map((tweet) => deleteTweet(tweet)))
  }

  const deleteUsers = async () => {
    return Promise.all(users.map((user) => deleteUser(user)))
  }

  await deleteTweets()
  await deleteUsers()
}

In this code snippet, the clearData function retrieves all users and tweets from the database. Then, it defines the deleteUser and deleteTweet functions, which delete individual user and tweet entries, respectively. The deleteTweets function makes use of Promise.all() to ensure that all tweets are deleted before starting to delete users. Finally, the deleteUsers function deletes all users.

This approach ensures that the relation between the tweets and users tables is properly handled during the deletion process.

By utilizing these methods, you can easily clear the database in your Prisma-powered application and effectively remove test data.

Tags: Prisma, database management, data deletion, relation handling