***
title: "CollectionFilter"
generated: true
---------------
A CollectionFilter defines a rule which can be used to associate ProductVariants with a Collection.
The filtering is done by defining the `apply()` function, which receives a TypeORM
[`QueryBuilder`](https://typeorm.io/#/select-query-builder) object to which clauses may be added.
Creating a CollectionFilter is considered an advanced Vendure topic. For more insight into how
they work, study the [default collection filters](https://github.com/vendurehq/vendure/blob/master/packages/core/src/config/catalog/default-collection-filters.ts)
Here's a simple example of a custom CollectionFilter:
*Example*
```ts
import { CollectionFilter, LanguageCode } from '@vendure/core';
export const skuCollectionFilter = new CollectionFilter({
args: {
// The `args` object defines the user-configurable arguments
// which will get passed to the filter's `apply()` function.
sku: {
type: 'string',
label: [{ languageCode: LanguageCode.en, value: 'SKU' }],
description: [
{
languageCode: LanguageCode.en,
value: 'Matches any product variants with SKUs containing this value',
},
],
},
},
code: 'variant-sku-filter',
description: [{ languageCode: LanguageCode.en, value: 'Filter by matching SKU' }],
// This is the function that defines the logic of the filter.
apply: (qb, args) => {
const LIKE = qb.connection.options.type === 'postgres' ? 'ILIKE' : 'LIKE';
return qb.andWhere(`productVariant.sku ${LIKE} :sku`, { sku: `%${args.sku}%` });
},
});
```
```ts title="Signature"
class CollectionFilter extends ConfigurableOperationDef {
constructor(config: CollectionFilterConfig)
apply(qb: SelectQueryBuilder, args: ConfigArg[]) => SelectQueryBuilder;
}
```
* Extends: [`ConfigurableOperationDef`](/current/core/reference/typescript-api/configurable-operation-def/#configurableoperationdef)``
### apply
\
ProductVariant>, args: ConfigArg[]) => SelectQueryBuilder<ProductVariant>`} />