Formatter is very fragile #44

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1. carbonrobot

   added

   bugSomething isn't workingSomething isn't working

   documentationImprovements or additions to documentationImprovements or additions to documentation

   on Nov 6, 2023
2. carbonrobot commented on Nov 7, 2023

   

   carbonrobot

   on Nov 7, 2023

   Contributor

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   pino runs the custom destination as the last function in the call chain, so the level and messagekey are not known to pino-lambda by the time pino calls our formatter. The fix is pretty simple, however, by supplying your own custom formatter.

   import { LogData, ILogFormatter } from 'pino-lambda';
   
   class CustomLogFormatter implements ILogFormatter {
     format(data: LogData): string {
       const { 
         awsRequestId,
         // your custom message key
         customMessageKey,
         // your custom level label key
         status
       } = data;
   
       // extract parts for message format
       const time = new Date().toISOString();
   
       return `${time}${
         awsRequestId ? `\t${awsRequestId}` : ''
       }\t${status.toUpperCase()}\t${msg}\t${JSON.stringify(data)}`;
     }
   }
   
   const destination = pinoLambdaDestination({
     formatter: new CustomLogFormatter(),
   });
   const logger = pino(destination);
3. carbonrobot

   removed

   bugSomething isn't workingSomething isn't working

   on Nov 7, 2023
4. alexander-williamson commented on Dec 19, 2025

   

   alexander-williamson

   on Dec 19, 2025

   Last edited by alexander-williamson

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   We also ran into something similar - we would like to use the library but have our messageKey go from msg to message

   PS thanks for this library, it's really useful !

   ❤️React with ❤️1Reacted by Charlie Brown