Not all data is flat like the data we have been using so far in this book. Of course, if we are building the system that Elasticsearch will be a part of, we can create a structure that is convenient for Elasticsearch. Of course, the structure can't always be flat, because not all use cases allow that. Let's see how to create mappings that use fully-structured JSON objects.

{
  "book" : {
    "author" : {
      "name" : {
        "firstName" : "Fyodor",
        "lastName" : "Dostoevsky"
      }
    },
    "isbn" : "123456789",
    "englishTitle" : "Crime and Punishment",
    "year" : 1886,
    "characters" : [
      {
        "name" : "Raskolnikov"
      }, 
      {
        "name" : "Sofia"
      }
    ],
    "copies" : 0
  }
}