JSONiqs

JSONiqs are a family of declarative query languages designed for processing JSON data. They extend the XQuery family to provide native querying, transforming, and constructing of JSON documents. Like XQuery, JSONiqs rely on aFLWOR-style expressions (for/let/where/order by/return) to express complex data workflows, but they adapt the data model and constructors to JSON’s objects and arrays.

Data model and syntax

JSONiqs operate directly on the JSON data model, which consists of objects (key/value pairs), arrays, strings, numbers, booleans, and null. The language provides JSON-specific constructors for building JSON values, along with path expressions and navigation helpers to extract and transform data. Although the syntax borrows heavily from XQuery, the emphasis is on producing and consuming JSON rather than XML, and many builtin functions are tailored to JSON types and semantics.

Semantics and features

Key features include expressive data filtering, sorting, grouping, and joining capabilities, as well as subqueries and modular program structure. JSONiqs are designed to support efficient querying of large JSON datasets and to enable transformations that generate new JSON structures or convert results to other formats, such as JSON or XML, depending on the implementation. The language also supports user-defined functions and libraries to promote reuse and composability.

Implementations and ecosystem

Several implementations exist for JSONiqs, with notable examples including the Zorba project and other XML database platforms that provide JSONiq support through extensions. The ecosystem emphasizes interoperability with JSON databases, RESTful services, and data integration workflows, enabling querying and transforming JSON in both standalone and integrated environments.

Use cases

Common use cases include extracting data from JSON documents stored in NoSQL or document stores, transforming data into new JSON structures for APIs, and integrating JSON data into XML pipelines or relational workflows. JSONiqs offer a higher-level alternative to ad hoc scripting for JSON data-intensive tasks.