org.apache.logging.log4j.layout.template.json.resolver

Class MessageResolver

java.lang.Object

org.apache.logging.log4j.layout.template.json.resolver.MessageResolver

All Implemented Interfaces:

EventResolver, TemplateResolver<LogEvent>

public final class MessageResolver
extends Object
implements EventResolver

Message resolver.

Configuration

 config      = [ stringified ] , [ fallbackKey ]
 stringified = "stringified" -> boolean
 fallbackKey = "fallbackKey" -> string
 

Examples

Resolve the message into a string:

 {
   "$resolver": "message",
   "stringified": true
 }
 

Resolve the message such that if it is a ObjectMessage or MultiformatMessage with JSON support, its emitted JSON type (string, list, object, etc.) will be retained:

 {
   "$resolver": "message"
 }
 

Given the above configuration, a SimpleMessage will generate a "sample log message", whereas a MapMessage will generate a {"action": "login", "sessionId": "87asd97a"}. Certain indexed log storage systems (e.g., Elasticsearch) will not allow both values to coexist due to type mismatch: one is a string while the other is an object. Here one can use a fallbackKey to work around the problem:

 {
   "$resolver": "message",
   "fallbackKey": "formattedMessage"
 }
 

Using this configuration, a SimpleMessage will generate a {"formattedMessage": "sample log message"} and a MapMessage will generate a {"action": "login", "sessionId": "87asd97a"}. Note that both emitted JSONs are of type object and have no type-conflicting fields.

Method Summary

Modifier and Type	Method and Description
void	resolve(LogEvent logEvent, JsonWriter jsonWriter) Resolves the given value using the provided JsonWriter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.logging.log4j.layout.template.json.resolver.TemplateResolver

isFlattening, isResolvable, isResolvable, resolve

Method Detail

resolve

public void resolve(LogEvent logEvent,
                    JsonWriter jsonWriter)

Description copied from interface: TemplateResolver

Resolves the given value using the provided JsonWriter.

Specified by:

resolve in interface TemplateResolver<LogEvent>