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# Method name: webMethod(permissions: Permissions, _function: Function, options: Options)

# Method package: wixWebModule

# Method menu location: wixWebModule --> webMethod

# Method Link: https://dev.wix.com/docs/velo/apis/wix-web-module/web-method.md

# Method Description:

Defines a backend function that can be called from the frontend.

The `webMethod()` function is a wrapper used to export functions from backend code that can be called from the frontend. 

The `permissions` parameter is used to define the permissions needed to call the function in frontend code. Import
the `Permissions` enum from the `wix-web-module` module to define the permissions. 
The permission options are:
 - `Permissions.Anyone`: Any site visitor can call the function.
 - `Permissions.Admin`: Only site admins can call the function.
 - `Permissions.SiteMember`: Only site members can call the function.


The `cache` object, found in the `options` parameter, allows you to cache or temporarily store the return value of web methods. Use the `ttl` property to define the duration, in seconds, for which you want the return value to be cached. If the Time To Live (TTL) is not set, the default value is `604800` seconds, which is approximately 1 week. 

Assign identifiers to caches using the `tags` property of the `cache` object. Tags enable you to specify cached return values that may require invalidation due to significant changes in your data. To invalidate web method caches, use the [`invalidateCache()`](https://dev.wix.com/docs/velo/api-reference/wix-cache-backend/cache/invalidate-cache.md) function from `wix-cache-backend`. Once invalidated, the return value is re-cached the next time your backend function is called. Learn more about [web method caching](https://dev.wix.com/docs/develop-websites/articles/best-practices/caching/about-web-method-caching.md).



>__Important:__
> - The `tags` property is required for caching. Without tags, nothing is cached. 
> - The `invalidateCache()` method from [wix-cache-backend](https://dev.wix.com/docs/velo/api-reference/wix-cache-backend/cache/invalidate-cache.md) is currently in developer preview.




Web methods must be defined in files with a `.web.js` extension.



# Method Code Examples:

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

## Export a backend function and use it in frontend code

```javascript
// Exporting a backend function from a '.web.js' file:
import {Permissions, webMethod} from "wix-web-module";

export const multiply = webMethod(Permissions.Anyone, (a,b) => a * b);

// Using the function in frontend code:
import {multiply} from "backend/multiply.web";

$w.onReady(async function () {
  multiply(5, 3).then((result) => {
    console.log(result); // Logs 15
  });
});
```

## Export and cache the return value

```javascript
import { Permissions, webMethod } from "wix-web-module";
import { currencies } from "wix-ecom.v2";

export const getConversionRate = webMethod(
  Permissions.Anyone, 
  async () => {
  try {
    const conversionRate = await currencies.getConversionRate("USD", "GBP");
    const rate = conversionRate.rate;
    const timestamp = conversionRate.rateTimestamp;

    return conversionRate;
  } catch (error) {
    console.error(error);
    // Handle the error
  }
},
{
  cache: {
    tags: ["currency", "USD", "GBP"],
    ttl: 86400 // Cache TTL in seconds (1 day)
  }
});

/* Promise resolves to:
 *  {
 *    "rate": {
 *       value: "20",
 *       decimalPlaces: 2
 *    },
 *    "rateTimestamp": "2020-03-15T20:00:00.181Z"
 *  }
 */
```

## Export and cache the return value of `getConversionRate()` for 1 day

```javascript
import { Permissions, webMethod } from "wix-web-module";
import { currencies } from "wix-ecom.v2";

export const getConversionRate = webMethod(
  Permissions.Anyone, 
  async () => {
  try {
    const conversionRate = await currencies.getConversionRate("USD", "GBP");
    const rate = conversionRate.rate;
    const timestamp = conversionRate.rateTimestamp;

    return conversionRate;
  } catch (error) {
    console.error(error);
    // Handle the error
  }
},
{
  cache: {
    tags: ["currency", "USD", "GBP"],
    ttl: 86400 // Cache TTL in seconds (1 day)
  }
});

/* Promise resolves to:
 *  {
 *    "rate": {
 *       value: "20",
 *       decimalPlaces: 2
 *    },
 *    "rateTimestamp": "2020-03-15T20:00:00.181Z"
 *  }
 */
```

## Export and cache the return value of `listPosts()` for 1 week

```javascript
import { Permissions, webMethod } from "wix-web-module";
import { posts } from "wix-blog-backend";

// List blog posts
const listBlogPostsFunction = async () => {
  try {
    const results = await posts.listPosts();
    return results.posts;
  } catch (error) {
    console.error("Error fetching blog posts:", error);
    // Handle the error
  }
};

// Exported web method that caches blog posts
export const getCachedBlogPosts = webMethod(
  Permissions.Anyone,
  listBlogPostsFunction,
  {
    cache: {
      tags: ["blogPosts", "blog"],
      ttl: 604800, // Cache TTL in seconds (7 days)
    },
  }
);
```

## Export and cache the return value of `queryContacts()` for 1 month with `elevate()`

```javascript
import { Permissions, webMethod } from "wix-web-module";
import { contacts } from "wix-crm.v2";
import { elevate } from "wix-auth";

/* Sample contact ID value: "2ca312b3-e850-465a-9991-c59c9c140919" */

const elevatedGetContact = elevate(contacts.getContact);

export const myGetContactFunction = webMethod(
  Permissions.Anyone,
  async (id) => {
    try {
      const contact = await elevatedGetContact(id);

      return contact;
    } catch (error) {
      console.log(error);
      // Handle the error
    }
  },
  {
    cache: {
      tags: ["contact", "crm"],
      ttl: 2628000, // Cache TTL in seconds (1 month)
    },
  }
);
```

---