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## Resource: wix-data

## Namespace: wix-data-filter

## Article: Introduction

## Article Link: https://dev.wix.com/docs/velo/apis/wix-data/wix-data-filter/introduction.md

## Article Content:

# Introduction
The `WixDataFilter` functions enable you to filter and control which results are returned by a dataset when the
[`setFilter()`](https://dev.wix.com/docs/velo/api-reference/wix-dataset/dataset/set-filter.md)  function is applied.

A filter is used to control which data is contained in a dataset on your page.

Typically, you  build a filter using the [`filter()`](wix-data.html#filter) function, refine the filter with `WixDataFilter` functions, and then apply the filter to the dataset using the [`setFilter()`](https://dev.wix.com/docs/velo/api-reference/wix-dataset/dataset/set-filter.md) function.

For example, the following code shows a filter on a dataset that is connected to a collection containing customer data. The filter includes only customers over the age of 20:

```javascript
 import wixData from 'wix-data';

 const customerFilter = wixData.filter()
   .gt("age", 20);

 $w("#myDataset").setFilter(customerFilter);


 ```
When working with [Wix app collections](https://support.wix.com/en/article/velo-working-with-wix-app-collections-and-code), check [which fields](https://support.wix.com/en/search?term=velo%20collection%20fields) can be used in a filter.