Merge pull request #494 from myzeprog/492-review-request-body-trouble…

…shooting

Update TROUBLESHOOTING.md

TROUBLESHOOTING.md

@@ -13,6 +13,7 @@ If you can't find a solution below, please open an [issue](https://github.com/se
 * [Environment Variables and Your SendGrid API Key](#environment)
 * [Using the Package Manager](#package-manager)
 * [Fixing Error 415](#error-415)
+* [Viewing the Request Body](#request-body)
 
 <a name="migrating"></a>
 ## Migrating from v2 to v3
@@ -99,3 +100,14 @@ If you're getting the following error while using this library:
 It is most likely due to a linebreak in your API key. Passing your key through `trim` should fix this:
 
 `$apiKey = trim($apiKey)`
+
+<a name="request-body"></a>
+## Viewing the Request Body
+
+When debugging or testing, it may be useful to examine the raw request body to compare against the [documented format](https://sendgrid.com/docs/API_Reference/api_v3.html).
+
+You can do this right before you call `$response = $sg->client->mail()->send()->post($mail);` like so:
+
+```php
+echo json_encode($mail, JSON_PRETTY_PRINT);
+```