# Getting started

Once you've installed your packages as described in the [last section](https://docs.highsidelabs.co/feed-transformer/quickstart), you can start converting feeds. It's really simple.

### Convert a feed file

Say you want to convert your `POST_PRODUCT_IMAGE_FEED` into a forward-compatible JSON format. Here's all you need to do:

```php
use SellingPartnerApi\FeedTransformer\Transformer;
use SellingPartnerApi\FeedTransformer\FeedTypes\ProductImage;

$feedPath = 'path/to/your/feed.xml';
$json = Transformer::fromFile(
    ProductImage::$feedType,  // -> POST_PRODUCT_IMAGE_DATA
    $feedPath,
    'ATVPDKIKX0DER'  // -> US Selling Partner API marketplace ID
);

$jsonFeedPath = 'path/to/new/feed.json';
file_put_contents($jsonFeedPath, json_encode($json));
```

The third parameter, `marketplaceId`, should be a valid Selling Partner API marketplace ID (full list [here](https://developer-docs.amazon.com/sp-api/docs/marketplace-ids)) corresponding to the marketplace that you're uploading the feed to.

That's it! You can now upload the file at `$jsonFeedPath` to Amazon the same way you were uploading your original feed, but replacing the original feed type (`POST_PRODUCT_IMAGE_FEED`) with `JSON_LISTINGS_FEED` in your request.

### Convert a feed file from a string

Instead of passing a file path to the converter, you can pass the feed contents to `Converter::convertFromString()` instead:

```php
use SellingPartnerApi\FeedTransformer\Transformer;
use SellingPartnerApi\FeedTransformer\FeedTypes\ProductImage;

$feedContents = '.....';
$json = Transformer::fromString(
    ProductImage::$feedType,  // -> POST_PRODUCT_IMAGE_DATA
    $feedContents,
    'ATVPDKIKX0DER'  // -> US Selling Partner API marketplace ID
);

$jsonFeedPath = 'path/to/new/feed.json';
file_put_contents($jsonFeedPath, json_encode($json));
```

### Feed-specific options

There's a fourth, optional argument to `Converter::convert()` and `Converter::convertFromString()`: an array of feed-type-specific parameters. Some feed types do not have any extra parameters, like the `POST_PRODUCT_IMAGE_FEED` used in the example above

All flat file feed types require an extra `merchantId` parameter. You can find your region-specific Amazon merchant ID [here](https://docs.highsidelabs.co/feed-transformer/feed-types).

{% hint style="info" %}
(If you primarily sell outside the US and that merchant ID link doesn't work for you, try copying it and replacing `sellercentral.amazon.com` with the Seller Central URL that you usually use.)
{% endhint %}

Here's what it looks like to pass feed-type-specific parameters:

```php
use SellingPartnerApi\FeedTransformer\Transformer;
use SellingPartnerApi\FeedTransformer\FeedTypes\Invloader;

$feedFile = 'path/to/your/feed.xml';
$json = Transformer::fromFile(
    Invloader::$feedType,  // -> POST_FLAT_FILE_INVLOADER_DATA
    $feedFile,
    'ATVPDKIKX0DER',
    ['merchantId' => 'A2DI..........']
);

$jsonFeedPath = 'path/to/new/feed.json';
file_put_contents($jsonFeedPath, json_encode($json));
```

Feed-specific parameters are defined on the individual feed type documentation pages.