> ## Documentation Index
> Fetch the complete documentation index at: https://docs.omni.co/llms.txt
> Use this file to discover all available pages before exploring further.

# required - Filter operators

> Keeps a default filter on a topic or composite topic from being removed, while still letting users change its value.

Marks a [`default_filters`](/modeling/topics/parameters/default-filters) entry on a topic or composite topic as required. Users can still change the filter's value, but they can't remove the filter from the query. If a query ends up with no value for the field (for example, a user clears it), Omni reapplies the declared default.

`required` is only meaningful inside a topic or composite topic's `default_filters`. Setting it on [`always_where_filters`](/modeling/topics/parameters/always-where-filters) or `always_having_filters` has no effect.

A `required` entry must specify a value. You can't set `required: true` without also giving the filter a value.

## Syntax

```yaml theme={null}
default_filters:
  <field_reference>:
    <filter_operator>: <value>
    required: true
```

## Properties

**field\_reference** `object` *required*

The field to filter on.

**filter\_operator** `any` *required*

The filter operator and value to apply. Refer to the [filter syntax documentation](/modeling/filters) for available operators like `is`, `not`, `contains`, `greater_than`, etc.

**required** `boolean`

If `true`, users can change the filter's value but can't remove the filter from the query. If a query omits the field or clears its value, Omni reapplies the declared default.

## Examples

```yaml theme={null}
default_filters:
  payments.currency_selector:
    is: EUR
    required: true
```


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.