Pattern layout

• type - pattern
• pattern - string - specifier for the output format, using placeholders as described below
• tokens - object (optional) - user-defined tokens to be used in the pattern

Pattern format

The pattern string can contain any characters, but sequences beginning with % will be replaced with values taken from the log event, and other environmental values.

Format for specifiers is %[padding].[truncation][field]{[format]} - padding and truncation are optional, and format only applies to a few tokens (notably, date). e.g. %5.10p - left pad the log level by 5 characters, up to a max of 10.

Fields can be any of:

• %r time in toLocaleTimeString format,
• %p log level,
• %c log category,
• %h hostname,
• %m log data,
• %j log data as JSON,
• %d date, formatted - default is ISO8601, format options are: ISO8601, ISO8601_WITH_TZ_OFFSET, ABSOLUTE, DATE, or any string compatible with the date-format library. e.g. %d{DATE}, %d{yyyy/MM/dd-hh.mm.ss},
• %% % - for when you want a literal % in your output,
• %n newline,
• %z process id (from process.pid),
• %x{[tokenname]} add dynamic tokens to your log. Tokens are specified in the tokens parameter,
• %X{[tokenname]} add values from the Logger context. Tokens are keys into the context values,
• %[ start a colored block (color will be taken from the log level, similar to coloredLayout),
• %] end a colored block.

Tokens

User-defined tokens can be either a string or a function. Functions will be passed the log event, and should return a string. For example, you could define a custom token that outputs the log event's context value for user like so:

import {Logger} from "@tsed/logger";

const logger = new Logger("loggerName");

logger.appenders.set("std-log-custom", {
  type: "console",
  layout: {
    type: "pattern",
    pattern: "%d %p %c %x{user} %m%n",
    tokens: {
      user: (logEvent) => AuthLibrary.currentUser()
    }
  },
  level: ["debug", "info", "trace"]
});
logger.info("doing something.");

This would output:

2017-06-01 08:32:56.283 INFO default charlie doing something.

You can also use the Logger context to store tokens (sometimes called Nested Diagnostic Context, or Mapped Diagnostic Context) and use them in your layouts.

import {Logger} from "@tsed/logger";
const logger = new Logger("loggerName");

logger.appenders.set("std-log", {
  type: "console",
  layout: {
    type: "pattern",
    pattern: "%d %p %c %X{user} %m%n"
  },
  level: ["debug", "info", "trace"]
});
logger.context.add("user", "charlie");
logger.info("doing something.");

This would output:

2017-06-01 08:32:56.283 INFO default charlie doing something.

TIP

Note that you can also add functions to the Logger Context, and they will be passed the logEvent as well.