# Plugin Helper: Inject

The `inject` plugin helper injects values into events according to the configuration.

Here is an example:

```ruby
require 'fluent/plugin/filter'

module Fluent::Plugin
  class ExampleFilter < Filter
    Fluent::Plugin.register_filter('example', self)

    # 1. Load inject helper
    helpers :inject

    # Omit `configure`, `shutdown` and other plugin APIs

    def filter(tag, time, record)
      # 2. Inject values into `record`
      new_record = inject_values_to_record(tag, time, record)
      # edit new_record ...
      new_record
    end
  end
end
```

For more details, see [Inject section](https://docs.fluentd.org/configuration/inject-section).

## Methods

### `inject_values_to_record(tag, time, record)`

This method injects values to the given record and returns the new record.

* `tag`: the tag of the event
* `time`: event timestamp
* `record`: event record

Example:

```ruby
def filter(tag, time, record)
  new_record = inject_values_to_record(tag, time, record)
  # edit new_record ...
  new_record
end
```

### `inject_values_to_event_stream(tag, es)`

This method injects values into the given event stream and returns the new event stream.

* `tag`: the tag of the event
* `es`: event stream

Example:

```ruby
def process(tag, es)
  new_es = inject_values_to_event_stream(tag, es)
  # do something using new_es
end
```

## Plugins using `inject`

* [`filter_stdout`](https://docs.fluentd.org/filter/stdout)
* [`out_exec`](https://docs.fluentd.org/output/exec)
* [`out_exec_filter`](https://docs.fluentd.org/output/exec_filter)
* [`out_file`](https://docs.fluentd.org/output/file)
* [`out_stdout`](https://docs.fluentd.org/output/stdout)

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.