JSON-e is a data-structure parameterization system for embedding context in JSON objects.

The central idea is to treat a data structure as a "template" and transform it, using another data structure as context, to produce an output data structure.

There are countless libraries to do this with strings, such as mustache. What makes JSON-e unique is that it operates on data structures, not on their textual representation. This allows input to be written in a number of formats (JSON, YAML, etc.) or even generated dynamically. It also means that the output cannot be "invalid", even when including large chunks of contextual data.

JSON-e is also designed to be safe for use on untrusted data. It never uses eval or any other function that might result in arbitrary code execution. It also disallows unbounded iteration, so any JSON-e rendering operation will finish in finite time.

This repository both defines the JSON-e language and contains several implementations of that language.

The language definition is embodied in ./specification.yml and the documentation for the language constructs.

The language and implementations are all versioned together, following semantic versioning. Breaking changes to the language specification are not common, and typically result from bugfixes rather than new features. Generally, you may consider the language stable.

Any discrepancy in behavior between the implementations that is not documented as undefined behavior is considered a bug. If fixing that bug can cause backward incompatibility in an implementation, then the change may be considered breaking and be released with a new major version.

• json-everything provides a implementation in .NET.

See json-e.js.org.

See CHANGELOG.rst for the changes in each version of this library.

Where is JSON-e used?

• AlterSchema specifies upgrades as a set of declarative transformation rules written in JSON Schema itself and JSON-e.
• Taskcluster uses JSON-e extensively to generate task definitions from various JSON-shaped inputs such as GitHub events.

(feel free to submit a PR to add your project here)