---
url: https://talkjs.com/docs/UI_Components/React_Native/Object_Types/CustomFieldPredicate
---

# CustomFieldPredicate

Filter custom fields by value or existence.

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```typescript
type CustomFieldPredicate = FieldPredicate<string> | 'exists' | '!exists';
```

A `CustomFieldPredicate` must either be:

- A string equal to `"exists"` or `"!exists"`
- A [`FieldPredicate<T>`](/docs/UI_Components/React_Native/Object_Types/FieldPredicate/) where **T** is of type `string`.

## Used by

- [`CustomPredicate`](/docs/UI_Components/React_Native/Object_Types/CustomPredicate/)
- [`ConversationPredicate`](/docs/UI_Components/React_Native/Object_Types/ConversationPredicate/)