Prisma Custom Transaction Handler

prisma.ts

// Prisma custom transaction handler
// I'm just add supported transactions options
// Please read more:
// https://github.com/prisma/prisma/issues/22309
// https://github.com/prisma/prisma-client-extensions/tree/main/callback-free-itx
// https://github.com/prisma/prisma-client-extensions/pull/52

import { Prisma, PrismaClient } from '@prisma/client';

const prisma = new PrismaClient({
    errorFormat: 'pretty',
    log: [
        {
            emit: 'event',
            level: 'query',
        },
        {
            emit: 'stdout',
            level: 'error',
        },
        {
            emit: 'stdout',
            level: 'info',
        },
        {
            emit: 'stdout',
            level: 'warn',
        },
    ],
});

const green = '\x1b[32m';
const reset = '\x1b[0m';

prisma.$on('query', (e) => {
    console.log(`Query: \n${green} ${e.query} ${reset}`);
    console.log(`Params: ${e.params}`);
    console.log(`Duration: ${e.duration} ms`);
    console.log(`Timestamp: ${e.timestamp}\n`);
});

type PrismaFlatTransactionClient = Prisma.TransactionClient & {
    $commit: () => Promise<void>;
    $rollback: () => Promise<void>;
};

type PrismaTransactionOptions = {
    maxWait?: number;
    timeout?: number;
    isolationLevel?: Prisma.TransactionIsolationLevel;
};

const ROLLBACK = { [Symbol.for('prisma.client.extension.rollback')]: true };

const xprisma = prisma.$extends({
    client: {
        async $begin(options?: PrismaTransactionOptions) {
            const prisma = Prisma.getExtensionContext(this);
            let setTxClient: (txClient: Prisma.TransactionClient) => void;
            let commit: () => void;
            let rollback: () => void;

            // a promise for getting the tx inner client
            const txClient = new Promise<Prisma.TransactionClient>((res) => {
                setTxClient = (txClient) => res(txClient);
            });

            // a promise for controlling the transaction
            const txPromise = new Promise((_res, _rej) => {
                commit = () => {
                    return _res(undefined);
                };
                rollback = () => {
                    return _rej(ROLLBACK);
                };
            });

            // opening a transaction to control externally
            if (
                '$transaction' in prisma &&
                typeof prisma.$transaction === 'function'
            ) {
                const tx = prisma
                    .$transaction((txClient) => {
                        setTxClient(
                            txClient as unknown as Prisma.TransactionClient,
                        );

                        return txPromise;
                    }, options)
                    .catch((e) => {
                        if (e === ROLLBACK) return;
                        throw e;
                    });

                // return a proxy TransactionClient with `$commit` and `$rollback` methods
                return new Proxy(await txClient, {
                    get(target, prop) {
                        if (prop === '$commit') {
                            return () => {
                                commit();
                                return tx;
                            };
                        }
                        if (prop === '$rollback') {
                            return () => {
                                rollback();
                                return tx;
                            };
                        }
                        if (prop === '$transaction') {
                            return async (
                                fn: (
                                    client: Prisma.TransactionClient,
                                    // biome-ignore lint/suspicious/noExplicitAny: <explanation>
                                ) => Promise<any>,
                            ) => {
                                return fn(target);
                            };
                        }
                        return target[prop as keyof typeof target];
                    },
                }) as PrismaFlatTransactionClient;
            }
            throw new Error('Transactions are not supported by this client');
        },
    },
});

const sleep = (ms: number) => new Promise((r) => setTimeout(r, ms));

async function exampleTransaction() {
    const tx = await xprisma.$begin({
        timeout: 10 * 1000, // 10s
    });

    // sleep 5s
    await sleep(5 * 1000);

    let user: {
        id: string;
        email: string;
    } | null;

    try {
        user = await tx.user.findFirst({ where: { email: '[email protected]' } });

        if (!user) {
            user = await tx.user.create({ data: { email: '[email protected]' } });
        } else {
            await tx.user.delete({ where: { id: user.id } });
        }
        await tx.$commit();
    } catch (error) {
        await tx.$rollback();
        throw error;
    }

    return { user: user };
}

const result = await exampleTransaction();
console.log(result);