What are Prisma middleware and how do you use them for audit logging in NestJS?

Q: What are Prisma middleware and how do you use them for audit logging in NestJS?

@Injectable() export class PrismaService extends PrismaClient implements OnModuleInit { constructor(private auditLogger: AuditLogService) { super(); } async onModuleInit() { // Middleware 1 — audit log all write operations this.$use(async (params, next) => { const before = Date.now(); const result = await next(params); const after = Date.now(); if (['create', 'update', 'delete'].includes(params.action)) { await this.auditLogger.log({ model: params.model, action: params.action, args: params.args, duration: after - before, }); } return result; }); // Middleware 2 — soft-delete filter applied globally this.$use(async (params, next) => { if (params.action === 'findMany' || params.action === 'findFirst') { params.args = params.args ?? {}; params.args.where = { ...params.args.where, deletedAt: null }; } return next(params); }); await this.$connect(); } } Middleware is registered with $use() before $connect() — order of registration determines execution order. params.model is the model name (e.g. 'User'); params.action is the operation (e.g. 'create', 'findMany'). Always call and return await next(params) — omitting it prevents the query from executing. Middleware runs for every query including those inside $transaction() callbacks. Prisma 5+ deprecates $use() in favor of Prisma Client Extensions — plan migrations accordingly.

Difficulty: 6/10

Prisma middleware, audit logging, NestJS integration

Prisma middleware are functions registered with $use() that intercept every query before and after execution. They receive params (model, action, args) and a next function. Use them for audit logging on write operations, global soft-delete filters, query performance monitoring, and cross-cutting data transformations.

Audit logging and soft-delete middleware

Prisma middleware design notes:

1
Middleware is registered with $use() before $connect() — order of registration determines execution order.
2

What are Prisma middleware and how do you use them for audit logging in NestJS?

Difficulty: 6/10

Prisma middleware, audit logging, NestJS integration

Prisma middleware are functions registered with $use() that intercept every query before and after execution. They receive params (model, action, args) and a next function. Use them for audit logging on write operations, global soft-delete filters, query performance monitoring, and cross-cutting data transformations.

Audit logging and soft-delete middleware

Prisma middleware design notes:

1
Middleware is registered with $use() before $connect() — order of registration determines execution order.
2

What are Prisma middleware and how do you use them for audit logging in NestJS?

What are Prisma middleware and how do you use them for audit logging in NestJS?

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