Plugin Helper: Record Accessor
The
record_accessor plugin helper provides unified access to the event record. It uses jsonpath like syntax for the target field. With this helper, you can easily access/delete a nested field in the plugin.Here is an example:
require 'fluent/plugin/filter'
module Fluent::Plugin
class ExampleFilter < Filter
Fluent::Plugin.register_filter('example', self)
# 1. Load record_accessor helper
helpers :record_accessor
def configure(conf)
super
# 2. Call `record_accessor_create` to create object
@accessor = record_accessor_create('$.user.name')
end
# Omit `super`, `shutdown` and other plugin APIs
def filter(tag, time, record)
# 3. Call `call` method to get value
value = @accessor.call(record) # With `$.user.name`, access to record["user"]["name"]
# ...
end
end
end
- dot notation:
$.is the starting parameter. Chain fields with dots..
For example:
$.event.level for record["event"]["level"]$.key1[0].key2 for record["key1"][0]["key2"]- bracket notation:
$[starting parameter. Chain fields with[].
Useful for special characters,
., whitespace, etc.$['dot.key'][0]['space key'] for record["dot.key"][0]["space key"]If you set non
$. or $[ starting value, e.g. key log, it is the same as record["log"]. So, using record_accessor does not break the existing plugin behavior.This method returns the accessor object of the event record.
The
param is a String.See the "Syntax" section for more details.
record_accessor_create("log")
record_accessor_create("$.key1.key2")
record_accessor_create("$['key1'][0]['key2']")
After creating an object, call
call/delete/set method with the record object.accessor.call(record) # get record field
accessor.delete(record) # delete record field
accessor.set(record, value) # set new value to record field
NOTE:
set method is supported since v1.10.3If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.
Last modified 1yr ago