---
title: Indexing pipeline extension condition syntax reference
slug: '64'
canonical_url: https://docs.coveo.com/en/64/
collection: index-content
source_format: adoc
---
# Indexing pipeline extension condition syntax reference
You can optionally add conditions on your extensions to control on which items they must be executed.
The condition is part of the extension configuration when you apply the extension to a source, not in the extension Python script itself.
This way, the Coveo indexing pipeline loads and executes the extension only for items for which the condition evaluates to True, allowing to optimize crawling performances.

You can [create an extension and apply it to a source from the Coveo Administration Console](https://docs.coveo.com/en/1936/).
Alternatively, you can [create it using the Coveo API](https://docs.coveo.com/en/146/).

See the information below for extension condition syntax and examples.

## Syntax

Indexing pipeline extension conditions are essentially built with metadata, metadata values, and operators.

* Metadata syntax: `%[metadataName]`

* Supported operators: `==`, `NOT`, `AND`, `OR`, `()`

> **Notes**
>
> * Operators are case insensitive.
> 
> * Values can be delimited in single or double quotes (`"value"` and `'value'` are equivalent and can be mixed in the same condition).
> 
> * Metadata name can contain special characters (such as `%`, `]`, `[`, `"` etc), but they must be escaped (for example, `%[meta1\[test\]]` is valid, `%[meta1[test]]` is not).
> 
> * Extensions without conditions are executed for all items.

## Condition syntax examples

The following table presents examples of the different condition syntax features that can help you [apply useful indexing pipeline extensions to sources](https://docs.coveo.com/en/1936/).

[%header,cols="2"]
|===
|Condition syntax example
|Evaluate to true if

|`%[meta1]`
|The metadata `meta1` exists on the item.

|`NOT %[meta1]`
|The metadata `meta1` doesn't exist on the item.

|`%[meta1] == "value"`
|The value of `meta1` equals `value`.

|`NOT %[meta1] == "value"`
|The metadata `meta1` doesn't exist, or it exists but its value isn't equal to `value`.

|`%[meta1] AND NOT %[meta1] == "value"`
|The metadata `meta1` exists, and its value isn't equal to `value`.

|`%[meta1] AND %[meta2]`
|Both metadata exist on the item.

|`%[meta1] == "value" AND %[meta2] == "value"`
|Both metadata values equal `value`.

|`%[meta1] OR %[meta2]`
|At least one of the metadata exists on the item.

|`%[meta1] == "value" OR %[meta2] == "value"`
|At least one of the metadata value equals `value`.

|`(%[meta1] OR %[meta2]) AND %[meta3]`
a|At least one of the metadata joined by `OR` exists on the item.

The metadata `meta3` exists on the item.

> **Note**
>
> When using more than one operator in a condition without parenthesis, the condition is evaluated with the following operator priority: `NOT` > `AND` > `OR`.

|`%[meta1] == ["value1", "value2"]`
|The metadata `meta1` equals either ["value1", "value2"] or ["value2", "value1"].
|===

## Pitfalls to Avoid

* You can't directly compare one metadata to another (for example, `%[meta1] == %[meta2]`).

Rather use:  `%[meta1] == 'value' AND %[meta2] == 'value'`

* You can't use operators between values (for example, `%[fruit] == 'apple' OR 'orange'` isn't valid).

Rather use: `%[fruit] == 'apple' OR %[fruit] == 'orange'`

* You can't use the inequality operator `!=`.

Rather use `NOT %[meta1] == 'value'`.

* Conditions don't support specifying an origin (`crawler`, `converter`, `mapping`).
The comparisons are always done using the latest value for the metadata so you must be aware of the indexing pipeline stage at which your extension is executed.