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# Method name: update(collectionId: string, item: object, options: WixDataOptions)

# Method package: wixData

# Method menu location: wixData --> update

# Method Link: https://dev.wix.com/docs/velo/apis/wix-data/update.md

# Method Description:

Updates an item in a collection.

The `update()` function returns a Promise that resolves to the updated
 item from the specified collection. The Promise is rejected if the
 current user does not have update permissions for the collection.

 Calling the `update()` function triggers the [`beforeUpdate()`](wix-data.Hooks.html#beforeUpdate)
 and [`afterUpdate()`](wix-data.Hooks.html#afterUpdate) hooks if they have been defined.


 The `update()` function compares the `_id` property of the specified
 item with the `_id` property values of the items in the specified
 collection. If an item in the collection has that `_id` value, `update()`
 replaces the item's property values with the ones in the specified item.
 If the existing item had properties with values and those properties were not
 included in the specified item, the values in those properties are lost. The
 item's `_updatedDate` property is also updated to the current date.

 Any valid JavaScript object can be used as a property value. The `update()`
 function maintains the structure of the specified object. For example,
 objects that contain nested objects, Arrays, or Arrays with nested objects
 are all added to the collection as defined.

 Use the `options` parameter to run `update()` from backend code without
 checking for permissions or without its registered hooks.

 When updating an item in a collection that has a reference field, set
 the value of the reference field to the referenced item's `_id` value or
 the entire referenced item object.

The maximum size of an item that you can update in a collection is 500kb.

 >**Notes:**
 > - The specified item must include an `_id` property that already exists in the collection.
 > - The `update()` function does not support multi-reference fields. For multi-reference fields, use [`replaceReferences()`](https://www.wix.com/velo/reference/wix-data/replacereferences) or [`insertReference()`](https://www.wix.com/velo/reference/wix-data/insertreference).
 > - [Translatable collections](https://support.wix.com/en/article/wix-multilingual-translating-cms-collection-content) do not allow insertion and modification of items when working in a non-primary language. For example, if a collection's primary language is English, and the site visitor is viewing the site in French, calling `update()` will fail and issue an error.



# Method Code Examples:

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

## Update an item with a specified ID in a collection

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

// ...

let toUpdate = {
  "_id":          "00001",
  "title":        "Mr.",
  "first_name":   "John",
  "last_name":    "Doe"
};

wixData.update("myCollection", toUpdate)
  .then((results) => {
    console.log(results); //see item below
 })
  .catch((err) => {
    console.log(err);
 });

/*  item is:
 *
 *  {
 *    "_id":          "00001",
 *    "_owner":       "ffdkj9c2-df8g-f9ke-lk98-4kjhfr89keedb",
 *    "_createdDate": "2017-05-24T12:33:18.938Z",
 *    "_updatedDate": "2017-05-24T12:33:18.938Z",
 *    "title":        "Mr.",
 *    "first_name":   "John",
 *    "last_name":    "Doe"
 *  }
 */
```

## Update an item in a collection using data options

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

// ...

let toUpdate = {
  "_id":          "00001",
  "title":        "Mr.",
  "first_name":   "John",
  "last_name":    "Doe"
};

let options = {
  "suppressAuth": true,
  "suppressHooks": true
};

wixData.update("myCollection", toUpdate, options)
  .then((results) => {
    console.log(results); //see item below
 })
  .catch((err) => {
    console.log(err);
 });

/*  item is:
 *
 *  {
 *    "_id":          "00001",
 *    "_owner":       "ffdkj9c2-df8g-f9ke-lk98-4kjhfr89keedb",
 *    "_createdDate": "2017-05-24T12:33:18.938Z",
 *    "_updatedDate": "2017-05-24T12:33:18.938Z",
 *    "title":        "Mr.",
 *    "first_name":   "John",
 *    "last_name":    "Doe"
 *  }
 */
```

## Get an item in a collection and update it

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

/*  existing item:
 *
 *  {
 *    "_id": "00001",
 *	  "title": "Mr.",
 *	  "first_name": "John",
 *    "last_name": "Doe"
 *  }
 *
 */

wixData.get("myCollection", "00001")
  .then((item) => {
    item.last_name = "Smith"; // updated last name
    wixData.update("myCollection", item);
    console.log(item); //see item below
  })
  .catch((err) => {
    console.log(err);
  }); 


/*  updated item:
 *
 *  {
 *    "_id": "00001",
 *	  "title": "Mr.",
 *	  "first_name": "John",
 *    "last_name": "Smith"
 *  }
 *
 */

```

## Query an item in a collection and update it

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

/*  existing item:
 *
 *  {
 *    "_id": "00001",
 *	  "title": "Mr.",
 *	  "first_name": "John",
 *    "last_name": "Doe"
 *  }
 *
 */

 wixData.query("myCollection")
  .eq("first_name", "John")
  .eq("last_name", "Doe")
  .find()
    .then((results) => {
      if(results.items.length > 0) {
        let item = results.items[0];
        item.last_name = "Smith"; // updated last name
        wixData.update("myCollection", item);
        console.log(item); //see item below
      } else {
        // handle case where no matching items found
      }
    })
    .catch((err) => {
      console.log(err);
    });

/*  updated item:
 *
 *  {
 *    "_id": "00001",
 *	  "title": "Mr.",
 *	  "first_name": "John",
 *    "last_name": "Smith"
 *  }
 *
 */

```

## Update an item including a reference to another item using the referenced item's ID

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

// ...

et countryId = "id-of-usa-item";

let toUpdate = {
  "_id":          "00001",
  "title":        "Mr.",
  "first_name":   "John",
  "last_name":    "Doe",
  "country":      countryId
};

wixData.update("myCollection", toUpdate)
  .then((results) => {
    console.log(results); //see item below
 })
  .catch((err) => {
    console.log(err);
 });

/*  item is:
 *
 *  {
 *    "_id":          "rifk4nrk-dj4o-djhe-oidk-fnoqw4oiglk4i",
 *    "_owner":       "ffdkj9c2-df8g-f9ke-lk98-4kjhfr89keedb",
 *    "_createdDate": "2017-05-24T12:33:18.938Z",
 *    "_updatedDate": "2017-05-24T12:33:18.938Z",
 *    "title":        "Mr.",
 *    "first_name":   "John",
 *    "last_name":    "Doe",
 *    "country":      "id-of-usa-item"
 *  }
 */
```

## Update an item including a reference to another item using the referenced item

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

// ...

let countryItem = // get country item from somewhere

let toUpdate = {
  "_id":          "00001",
  "title":        "Mr.",
  "first_name":   "John",
  "last_name":    "Doe",
  "country":      countryItem
};

wixData.update("myCollection", toUpdate)
  .then((results) => {
    console.log(results); //see item below
 })
  .catch((err) => {
    console.log(err);
 });

/*  item is:
 *
 *  {
 *    "_id":          "rifk4nrk-dj4o-djhe-oidk-fnoqw4oiglk4i",
 *    "_owner":       "ffdkj9c2-df8g-f9ke-lk98-4kjhfr89keedb",
 *    "_createdDate": "2017-05-24T12:33:18.938Z",
 *    "_updatedDate": "2017-05-24T12:33:18.938Z",
 *    "title":        "Mr.",
 *    "first_name":   "John",
 *    "last_name":    "Doe",
 *    "country":      "id-of-usa-item"
 *  }
 */
```

## Update a collection using a custom function

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

// Code for an update operation using update() //

function updateGreeting(itemId, language, greeting) {
  const toUpdate = {
    _id: itemId,
    language,
    greeting
  };

  return wixData.update('Greetings', toUpdate);
}

```

---