﻿---
title: Script condition
description: A watch condition that evaluates a script. The default scripting language is painless. You can use any of the scripting languages supported by Elasticsearch...
url: https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4429/explore-analyze/alerts-cases/watcher/condition-script
products:
  - Elasticsearch
---

# Script condition
A watch [condition](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4429/explore-analyze/alerts-cases/watcher/condition) that evaluates a script. The default scripting language is `painless`. You can use any of the scripting languages supported by Elasticsearch as long as the language supports evaluating expressions to Boolean values. Note that the `mustache` and `expression` languages are too limited to be used by this condition. For more information, see [Scripting](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4429/explore-analyze/scripting).

## Using a script condition

The following snippet configures an inline `script` condition that always returns `true`:
```js
"condition" : {
  "script" : "return true"
}
```

This example defines a script as a simple string. This format is actually a shortcut for defining an [inline](#condition-script-inline) script. The formal definition of a script is an object that specifies the script type and optional language and parameter values. If the `lang` attribute is omitted, the language defaults to `painless`. Elasticsearch supports two types of scripts, [inline](#condition-script-inline) and [stored](#condition-script-stored).
For example, the following snippet shows a formal definition of an `inline` script that explicitly specifies the language and defines a single script parameter, `result`:
```js
"condition" : {
  "script" : {
    "source" : "return params.result",
    "lang" : "painless",
    "params" : {
      "result" : true
    }
  }
}
```


## Inline scripts

Inline scripts are scripts that are defined in the condition itself. The following snippet shows the formal configuration of a simple painless script that always returns `true`.
```js
"condition" : {
  "script" : {
    "source" : "return true"
  }
}
```


## Stored scripts

Stored scripts refer to scripts that were [stored](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4429/explore-analyze/scripting/modules-scripting-using) in Elasticsearch. The following snippet shows how to refer to a script by its `id`:
```js
"condition" : {
  "script" : {
    "id" : "my_script"
  }
}
```

As with [inline](#condition-script-inline) scripts, you can also specify the script language and parameters:
```js
"condition" : {
  "script" : {
    "id" : "my_script",
    "lang" : "javascript",
    "params" : { "color" : "red" }
  }
}
```


## Accessing the watch payload

A script can access the current watch execution context, including the payload data, as well as any parameters passed in through the condition definition.
For example, the following snippet defines a watch that uses a [`search` input](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4429/explore-analyze/alerts-cases/watcher/input-search) and uses a `script` condition to check if the number of hits is above a specified threshold:
```js
{
  "input" : {
    "search" : {
      "request": {
        "indices" : "log-events",
        "body" : {
          "size" : 0,
          "query" : { "match" : { "status" : "error" } }
        }
      }
    }
  },
  "condition" : {
    "script" : {
      "source" : "return ctx.payload.hits.total > params.threshold",
      "params" : {
        "threshold" : 5
      }
    }
  }
}
```

When you’re using a scripted condition to evaluate an Elasticsearch response, keep in mind that the fields in the response are no longer in their native data types. For example, the `@timestamp` in the response is a string, rather than a `DateTime`. To compare the response `@timestamp` against the `ctx.execution_time`, you need to parse the `@timestamp` string into a `ZonedDateTime`. For example:
```js
java.time.ZonedDateTime.parse(@timestamp)
```

You can reference the following variables in the watch context:

| Name                         | Description                                       |
|------------------------------|---------------------------------------------------|
| `ctx.watch_id`               | The id of the watch that is currently executing.  |
| `ctx.execution_time`         | The time execution of this watch started.         |
| `ctx.trigger.triggered_time` | The time this watch was triggered.                |
| `ctx.trigger.scheduled_time` | The time this watch was supposed to be triggered. |
| `ctx.metadata.*`             | Any metadata associated with the watch.           |
| `ctx.payload.*`              | The payload data loaded by the watch’s input.     |