Early demo of Prisma client extensions

We are using the integration branch 4.7.0-integration-client-extensions.2.

Custom model

This demonstrates how a third party library can be used on a model to validate it.

Validation via joi

// Validation library
const Joi = require("joi");
const joiSchema = Joi.object({
  // We set a range for the age integer and we validate email adress.
  age: Joi.number().integer().min(0).max(120).required(),
  email: Joi.string().email().required(),
});

New validate method on User

// Extended Prisma Client which only adds `person` if the age and email are valid
const prismaWithCustomValidation = prisma.$extends({
  // Customizing models works at runtime
  model: {
    user: {
      // Create a custom method `validate` on user models. Returns true if data is valid.
      validate(data: unknown): data is User {
        const result = joiSchema.validate(data);
        return !result.error;
      },
    },
  },
});

How it could be used during signup

async function main() {
  console.log("Client Extensions Demo");

  // Invalid user signup
  await signup({ age: 150, email: "foo@bar.com" });

  // Invalid user signup
  await signup({ age: 50, email: "foobar.com" });

  // Valid user signup
  await signup({ age: 50, email: "foo@bar.com" });
}

async function signup(data: unknown) {
  const userData = data;
  if (prismaWithCustomValidation.user.validate(userData)) {
    console.log("Valid!");
    const user = await prismaWithCustomValidation.user.create({
      data: userData,
    });
  } else {
    // not valid
    console.log("not valid, hence no user created");
  }
}

Which should output:

Client Extensions Demo
not valid, hence no user created
not valid, hence no user created
Valid!

What is next

main.ts also contains some code showing query and result extensions which only work on a type level yet. But especially query will be handy for this example as we can then properly override create or update queries to ensure they only write valid data to the database.