@loopback/docs/site/apidocs/filter.wherebuilder.exists.md

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---
lang: en
title: 'API docs: filter.wherebuilder.exists'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/filter
permalink: /doc/en/lb4/apidocs.filter.wherebuilder.exists.html
---

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[Home](./index.md) &gt; [@loopback/filter](./filter.md) &gt; [WhereBuilder](./filter.wherebuilder.md) &gt; [exists](./filter.wherebuilder.exists.md)

## WhereBuilder.exists() method

Add a `exists` condition

**Signature:**

```typescript
exists<K extends KeyOf<MT>>(key: K, val?: boolean): this;
```

## Parameters

<table><thead><tr><th>

Parameter


</th><th>

Type


</th><th>

Description


</th></tr></thead>
<tbody><tr><td markdown="1">

key


</td><td markdown="1">

K


</td><td markdown="1">

Property name


</td></tr>
<tr><td markdown="1">

val


</td><td markdown="1">

boolean


</td><td markdown="1">

_(Optional)_ Exists or not


</td></tr>
</tbody></table>

**Returns:**

this