storageManager: Loading from remote storage

So when I set:

contentTypeJson: true,

resulting in:

storageManager: {
            type: 'remote',
            autoload: true,
            stepsBeforeSave: 1,
            contentTypeJson: true,
            urlStore: "/save-template/2",
            urlLoad: "/load-template/2", 
            params: {},   // For custom values on requests
          },

I can now load from the database. But, now it will not save, because it is sending the data as JSON. How can I send the data as POST variables, but receive it as JSON?

@shareefhiasat I explain here how to use them https://github.com/artf/grapesjs/wiki/Storage#store-and-load-templates

@DeathStapler This is what mine looks like:

{
    "gjs-css":"*{box-sizing: border-box;}body{margin:0;}.c1050{padding:10px;}", 
    "gjs-html":"<div class="c1050">Hi</div>", 
    "gjs-assets":"[]", 
    "gjs-styles":"[]", 
    "gjs-components":"[]"
  }

The thing that jumps out at me at first is that assets, components and styles should be arrays, you have empty strings.

The Content-Type is correct.