JSONiq: XQuery for JSON, JSON for XQuery

JSONiq: XQuery for JSON

JSONiq is a query language designed specifically for querying and manipulating JSON data, similar to how XQuery works for XML. It enables developers to work with JSON data structures easily, leveraging the power of query expressions.

Key Features of JSONiq

1. JSON-Centric Syntax: JSONiq provides a syntax that is intuitive for JSON data structures.
2. Integration with XQuery: JSONiq is influenced by XQuery, allowing users familiar with XQuery to transition to JSONiq smoothly.
3. Data Manipulation: Supports querying, transforming, and aggregating JSON data.

Basic Syntax

JSONiq uses expressions similar to those in XQuery but tailored for JSON. Here’s a basic structure:

for $item in json-doc("data.json")/array
return $item.name

Example JSON Document

Consider the following JSON:

{
  "library": [
    {
      "id": 1,
      "title": "Learning JSONiq",
      "author": "John Doe",
      "price": 29.99
    },
    {
      "id": 2,
      "title": "Advanced JSONiq",
      "author": "Jane Smith",
      "price": 39.99
    }
  ]
}

Example JSONiq Queries

1. Retrieve All Book Titles

for $book in json-doc("library.json")/library
return $book.title

2. Filter Books by Price

To find books with a price greater than 30:

for $book in json-doc("library.json")/library
where $book.price > 30
return {
  "title": $book.title,
  "author": $book.author
}

3. Aggregate Data

To calculate the average price of books:

let $prices := for $book in json-doc("library.json")/library
                return $book.price
return avg($prices)

JSON for XQuery

JSON for XQuery refers to the support for JSON data types and operations within XQuery. Many modern XQuery processors allow you to work with JSON data directly.

Storing and Querying JSON in XQuery

You can store JSON in XML databases that support JSON data types and use XQuery to manipulate it.

Example XQuery for JSON

Assuming you have JSON stored in a database, you can use XQuery to extract and manipulate it:

let $json := doc("data.json")
return $json/library

Conclusion

JSONiq provides a robust way to query and manipulate JSON data, drawing on the strengths of XQuery. It allows seamless integration of JSON handling in environments that traditionally use XML. If you have specific questions or need examples on either JSONiq or JSON handling in XQuery, feel free to ask!