Logging

Source URL: https://docs.prisma.io/docs/orm/prisma-client/observability-and-logging/logging

Logging

Learn how to configure Prisma Client to log the raw SQL queries it sends to the database and other information

Use the PrismaClient log parameter to configure log levels , including warnings, errors, and information about the queries sent to the database.

Prisma Client supports two types of logging:

• Logging to stdout (default)
• Event-based logging (use $on() method to subscribe to events)

You can also use the DEBUG environment variable to enable debugging output in Prisma Client. See Debugging for more information.

If you want a detailed insight into your Prisma Client’s performance at the level of individual operations, see Tracing.

Log to stdout

The simplest way to print all log levels to stdout is to pass in an array LogLevel objects:

    const prisma = new PrismaClient({
      log: ["query", "info", "warn", "error"],
    });

This is the short form of passing in an array of LogDefinition objects where the value of emit is always stdout:

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

Event-based logging

To use event-based logging:

1. Set emit to event for a specific log level, such as query
2. Use the $on() method to subscribe to the event

The following example subscribes to all query events and write the duration and query to console:

Relational databases

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

    prisma.$on("query", (e) => {
      console.log("Query: " + e.query);
      console.log("Params: " + e.params);
      console.log("Duration: " + e.duration + "ms");
    });

    Query: SELECT "public"."User"."id", "public"."User"."email", "public"."User"."name" FROM "public"."User" WHERE 1=1 OFFSET $1
    Params: [0]
    Duration: 3ms
    Query: SELECT "public"."Post"."id", "public"."Post"."title", "public"."Post"."authorId" FROM "public"."Post" WHERE "public"."Post"."authorId" IN ($1,$2,$3,$4) OFFSET $5
    Params: [2, 7, 18, 29]
    Duration: 2ms

MongoDB

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

    prisma.$on("query", (e) => {
      console.log("Query: " + e.query);
    });

    Query: db.User.aggregate([ { $project: { _id: 1, email: 1, name: 1, }, }, ])
    Query: db.Post.aggregate([ { $match: { userId: { $in: [ "622f0bbbdf635a42016ee325", ], }, }, }, { $project: { _id: 1, slug: 1, title: 1, body: 1, userId: 1, }, }, ])

The exact event (e) type and the properties available depends on the log level.