# Utilities for Outbound Feeds Development 

Source: https://dev.arcxp.com/arc-io/developer-docs/utilities-for-outbound-feeds-development/

In addition to the blocks that have been created for feeds and content-sources, several npm packages have been created to be used in the blocks as utilities to reduce duplicate code. All of the blocks packages end in `-block` to designate they are blocks and should be in the `blocks.json`. These utilities are normal npm packages that start with `feeds-` and must be included in the `package.json` dependencies.

## feeds-content-elements

This package is designed to take an array of `content_elements` from a story and convert the different content\_element types into xml. Each `content_element` type has its own function to convert the Arc XP Native Specification (ANS) to xml. Call the parse function and pass in the `content_elements` array, it will return a string of formatted xml. You might wonder why it returns a string of xml instead of an object, because the `xmlbuilder2 CDATA` function only takes a string.

```js
import { BuildContent } from '@wpmedia/feeds-content-elements'

const rssBuildContent = new BuildContent()

const body = rssBuildContent.parse(
  story.content_elements,
  includeContent, // 0-10 or "all" for how many content\_elements to include in the feed
  domain, // from blocks.json properties
  resizerKey, // from environment/index.js stored encrypted
  resizerURL, // from blocks.json properties
  resizerWidth, // optional width to resize all images
  resizerHeight, // optional height to resize all images
)
```

The parse function determines how much of each article to include using the includeContent, and uses a big switch statement to map each `content_element` type to the correct function. By breaking each one into its own function you can easily change how any `content_element` type is processed. If we want to change how headers are created we can create a new rssBuildContent function and redefine just the header function like.

```js
import { BuildContent } from '@wpmedia/feeds-content-elements'

function rssBuildContent() {
  BuildContent.call(this)

  this.header = (element) => {
    return {
      h1: {
        '@class': 'headline',
        '#': element.content,
      },
    }
  }
}
```

## feeds-find-video-stream

ANS Video can have multiple video encodings. These can be different video types (mp4, m3u8) and bit rates (300, 600, 1200, 2400, 5400). The types and sizes are configurable in VideoCenter and might be different for each client. Each video has a streams array to hold the encodings. This utility will search for video encodings based on the fields and values you pass in. You can use any field(s) that exist in the streams object to match a video encoding. The default fields and values are:

```
{ bitrate: 2000, stream_type: ‘mp4’ }
```

```js
import { findVideo } from '@wpmedia/feeds-find-video-stream'

const selectVideo = {
  bitrate: 5400,
  stream\_type: 'mp4',
}

const videoStream = findVideo(video.streams, selectVideo)
```

## feeds-promo-items

This package is designed to make it easier to process `promo_items`. Pass the story and the path to the `promo_items` (`promo_items.basic` || `promo_items.lead_art` by default) and it returns an array of objects ready to be added to the feed. Since it supports galleries, it always returns an array. It supports images, galleries and videos and can return them in three different formats. The three functions that can be called are:

- `imageTag` for use in sitemaps `<image:image>` tags
- `mediaTag` for use in RSS `<media:content>` tags
- `enclosureTag` for use in RSS `<enclosure>` tags

The three functions share a common set of helper functions to parse the image, gallery and video objects. This makes it easy to override just these functions to change the default functionality to what you need.

```js
import { BuildPromoItems } from '@wpmedia/feeds-promo-items'

const PromoItems = new BuildPromoItems()

const img = PromoItems.mediaTag({
    ans,
    promoItemsJmespath,
    resizerKey,
    resizerURL,
    resizerWidth,
    resizerHeight,
    imageTitle,
    imageCaption,
    imageCredits,
    videoSelect,
})

if (img) ({ '#': img })
```

## feeds-prop-types

Outbound Feeds can be broken down into sitemaps and rss feeds. Each type shares a common set of customFields. This utility is a convenient way to add some or all of the shared customFields to a feed. The function

`generatePropsForFeed( feedType, PropTypes, omit )`

- `feedType` \- Either sitemap or rss
- `PropType` \- The `fusion:prop-types`
- `omit` \- Array of `customFields` to exclude

### sitemap customFields

- `includePromo`
- `promoItemsJmespath`
- `resizerKVP`
- `lastMod`
- `priority`
- `changeFreq`

### rss customFields

- `channelTitle`
- `channelDescription`
- `channelCopyright`
- `channelTTL`
- `channelUpdatePeriod`
- `channelUpdateFrequency`
- `channelCategory`
- `channelLogo`
- `itemTitle`
- `itemDescription`
- `pubDate`
- `itemCredits`
- `itemCategory`
- `includePromo`
- `promoItemsJmespath`
- `resizerKVP`
- `imageTitle`
- `imageCaption`
- `imageCredits`
- `includeContent`
- `videoSelect`

To add the common `customFields` to an rss feed but exclude `includePromo`, call `generatePropsForFeed` like:

```js
import PropTypes from 'fusion:prop-types'
import { generatePropsForFeed } from '@wpmedia/feeds-prop-types'

rss.propTypes = {
  customFields: PropTypes.shape({
    ...generatePropsForFeed('rss', PropTypes, \['includePromo'\]
  })
}
```

If you want to add your own `customFields`, add them after the `generatePropsForFeed` call.

## feeds-resizer

All image urls must be generated using the resizer. This ensures the lowest latency and reduces potential impacts on your system. This also offers the opportunity to change the images width and or height if desired. The resizer function depends on a cryptographic key.

The `resizerKey` should be stored in `environment/index.js` as an encrypted value. The width and height are optional. If omitted the resizer will return the image’s original size. Call the resizer like:

```js
import { resizerKey } from 'fusion:environment'
import { buildResizerURL } from '@wpmedia/feeds-resizer'

const resizedURL = buildResizerURL(
  imageURL,
  resizerKey,
  resizerURL,
  width,
  height,
)
```

## feeds-xml-output

By default PageBuilder generates `html` output. To generate `xml` output a new `outputType` must be created. The `outputType` expects an object and uses the `xmlbuilder2` module to convert it to xml. In your repo the feeds-xml-output package has already been added to `package.json` and the `output-type` configured. By including the parameter `?outputType=xml` in all feeds requests tells fusion to use the `xml` output-type.