Extracting information from nested JSON objects with key/value relationships

Question

Extracting information from nested JSON objects with key/value relationships

Imagine a scenario where you have a JSON array with various key/value pairs in each object. While you already know how to target a specific key/value using JavaScript, what if you need to search through the entire JSON data to locate an item and also find a related pair within the same object?

For instance, how can you scan the JSON below for "Moby Dick" and then identify the author associated with that particular title?

"store": {
    "book": [ 
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      { "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      { "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ]
  }
}

javascript json

Answer 1

Answer №1

If this is the object you are working with:

let library = {
       "book": [ 
          {...}, {...}
        ]
     }

You can filter it like so:

let foundBooks = library.book.filter(function(book) { return book.title === "Moby Dick"});

As pointed out by @JLRiche, foundBooks is an array. To access the first match, you simply use array notation:

let selectedBook = foundBooks[0];

Answer 2

If this is the object you are working with:

let library = {
       "book": [ 
          {...}, {...}
        ]
     }

You can filter it like so:

let foundBooks = library.book.filter(function(book) { return book.title === "Moby Dick"});

As pointed out by @JLRiche, foundBooks is an array. To access the first match, you simply use array notation:

let selectedBook = foundBooks[0];

Answer 3

Answer №2

To locate the title, you must iterate through the list and develop custom functions, like this:

function searchForTitle(title) {
    for (var i = 0; i < data.store.book.length; i++) {
        if (data.store.book[i].title == title) {
            return data.store.book[i];
        }
    }
}

Using the function would look like this:

var matchingBook = searchForTitle("Moby Dick"),
    authorName = matchingBook.author;

Answer 4

To locate the title, you must iterate through the list and develop custom functions, like this:

function searchForTitle(title) {
    for (var i = 0; i < data.store.book.length; i++) {
        if (data.store.book[i].title == title) {
            return data.store.book[i];
        }
    }
}

Using the function would look like this:

var matchingBook = searchForTitle("Moby Dick"),
    authorName = matchingBook.author;

Answer 5

Answer №3

To retrieve information on the book titled "Moby Dick," iterate through your collection of book items and locate the one with a title matching "Moby Dick." Once found, examine the book.author property to identify the author of that specific book.

Answer 6

To retrieve information on the book titled "Moby Dick," iterate through your collection of book items and locate the one with a title matching "Moby Dick." Once found, examine the book.author property to identify the author of that specific book.

Extracting information from nested JSON objects with key/value relationships

Answer №1

Answer №2

Answer №3

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