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# Method name: beforeDistinct(distinct: WixDataDistinct, context: HookContext)

# Method package: wixDataHooks

# Method menu location: wixDataHooks --> beforeDistinct

# Method Link: https://dev.wix.com/docs/velo/events-service-plugins/data/hooks/wix-data-hooks/before-distinct.md

# Method Description:

A hook triggered before a distinct query operation.

The `beforeDistinct()` hook is triggered when the [`distinct()`](https://dev.wix.com/docs/velo/api-reference/wix-data/wix-data-query/distinct.md) method is called. It allows you to modify the [`WixDataDistinct`](https://dev.wix.com/docs/velo/apis/wix-data/wix-data-distinct/introduction.md) object before the distinct query runs.

Return a [`WixDataDistinct`](https://dev.wix.com/docs/velo/apis/wix-data/wix-data-distinct/introduction.md) object or a Promise that resolves to a `WixDataDistinct` object. The returned object defines the distinct query that runs instead of the original distinct query created by the [`distinct()`](https://dev.wix.com/docs/velo/api-reference/wix-data/wix-data-query/distinct.md) method.

If the returned value is of the wrong type, the value is ignored.

A rejected Promise blocks the call to [`distinct()`](https://dev.wix.com/docs/velo/api-reference/wix-data/wix-data-query/distinct.md) and triggers the [`onFailure()`](#onFailure) hook, if it has been registered.



# Method Code Examples:

*** Note: do not assume any prop names or enum values other than the ones in the example.

## A `beforeDistinct` hook

```javascript
// In data.js

export function myCollection_beforeDistinct(distinct, context) {
  let hookContext = context; // See below

  // Some change to the received query

  return distinct;
}

/*
 * hookContext:
 *
 * {
 *   "collectionName": "myCollection",
 *   "userId":         "f45jf8d2-grkj-2opd-4ovk-9rfj4wo5tvj3",
 *   "userRole":       "siteOwner"
 * }
 */
```

## Refine the distinct query before it runs

```javascript
// In data.js

export function myCollection_beforeDistinct(distinct, context) {
  let hookContext = context; // See below

  // Add a new restriction to the current filter
  const filter = distinct.getFilter();
  const updateFilter = filter.ge("price", 100);

  // Set the updated filter in the distinct query
  const updatedDistinct = distinct.filter(updateFilter);
  return updatedDistinct;
}

/*
 * hookContext:
 *
 * {
 *   "collectionName": "myCollection",
 *   "userId":         "f45jf8d2-grkj-2opd-4ovk-9rfj4wo5tvj3",
 *   "userRole":       "siteOwner"
 * }
 */
```

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