Using annotations or blocks for dynamic content in Sanity.io

Hello, welcome to my post called [postTitle]. It was created on [postPublishDate] by [postAuthor].

const content = props.data[props.children]

{
	name: "content",
	type:"array",
	of: [
		{
			type: "block",
			of:[{type: "attributeSelection"}]
		}
	]
}

{
	name:"attributeSelection",
	type:"object",
	fields:[{
		name:"attribute",
		type:"string",
		options:{
			list:[
			{title:"Publish date", value: "publishedAt"},
			//... and so on
			]
		}
	}]
}

export default {
    title: 'Block Content',
    name: 'blockContent',
    type: 'array',
    of: [
      {
        title: 'Block',
        type: 'block',
        styles: [
          //...
        ],
        lists: [
          //...
        ],
        marks: {
          decorators: [
            //...
          ],
          annotations: [
            //...
            {
              title: 'Dynamic Content',
              name: 'dynamicContent',
              type: 'object',
            }
          ]
        }
      },
    //...
    ]
  }

// "postTitle" works and returns "My Post Title successfully
{
  children: [
    0: "postTitle",
  ],
  data: {
    postTitle: "My Post Title",
    category: {
      title: "The Category Title",
    }
  }
}

// "category.title" returns undefined
{
  children: [
    0: "category.title",
  ],
  data: {
    postTitle: "My Post Title",
    category: {
      title: "The Category Title",
    }
  }
}

const content = props.data[props.children]