{"id":5643,"library":"json-e","title":"JSON-e","description":"JSON-e is a data-structure parameterization system designed to embed context within JSON objects. It allows treating a data structure as a 'template' and transforming it using another data structure as context to produce an output data structure. Unlike string-based templating, JSON-e operates directly on data structures, ensuring valid JSON output. The project maintains a healthy release cadence, with version 4.8.2 being the latest, and aims for stability with breaking changes typically resulting from bug fixes rather than new features.","status":"active","version":"4.8.2","language":"en","source_language":"en","source_url":"https://github.com/json-e/json-e","tags":["json","templating","data transformation","configuration","data structures"],"install":[{"cmd":"pip install json-e","lang":"bash","label":"Install latest version"}],"dependencies":[],"imports":[{"note":"While 'json' is Python's built-in JSON handler, 'json-e' is a separate library for data-structure parameterization. The documentation for the Python implementation's specific API is not prominently featured; the main project documentation refers to json-e.js.org for usage. This entry assumes a direct 'json_e' import if a high-level Python API exists as a standalone module within the PyPI package.","wrong":"import json","symbol":"json_e","correct":"import json_e"}],"quickstart":{"code":"import json\n\n# NOTE: This quickstart demonstrates the *concept* of JSON-e templating\n# using Python's built-in 'json' module for data handling. \n# A high-level, standalone Python API for the 'json-e' templating logic\n# is not extensively documented in public search results. \n# This example *simulates* a basic substitution operation.\n\ntemplate = {\n    \"message\": \"Hello, ${user.name}! Your ID is ${user.id}.\",\n    \"settings\": {\n        \"theme\": \"${config.theme}\",\n        \"darkMode\": \"${config.darkMode}\"\n    }\n}\n\ncontext = {\n    \"user\": {\n        \"name\": \"Alice\",\n        \"id\": \"12345\"\n    },\n    \"config\": {\n        \"theme\": \"dark\",\n        \"darkMode\": True\n    }\n}\n\ndef apply_template(template_data, context_data):\n    # This is a simplified, manual substitution for demonstration.\n    # A true JSON-e implementation would handle more complex operations ($eval, $if, $map, etc.)\n    template_str = json.dumps(template_data)\n    \n    # Basic string interpolation for demonstration\n    for key_outer, val_outer in context_data.items():\n        if isinstance(val_outer, dict):\n            for key_inner, val_inner in val_outer.items():\n                placeholder = f\"${{{key_outer}.{key_inner}}}\"\n                template_str = template_str.replace(placeholder, str(val_inner))\n        else:\n             placeholder = f\"${{{key_outer}}}\"\n             template_str = template_str.replace(placeholder, str(val_outer))\n    \n    # Attempt to parse the result back to a JSON object\n    return json.loads(template_str)\n\n\noutput = apply_template(template, context)\nprint(json.dumps(output, indent=2))","lang":"python","description":"This example illustrates the *concept* of data-structure parameterization that JSON-e provides, using Python's standard `json` module for serialization and deserialization. It manually demonstrates a simple substitution process, as a direct, high-level Python API for 'json-e' templating with an explicit `render` function is not readily available in public documentation."},"warnings":[{"fix":"Thoroughly consult the `json-e` GitHub repository's source code, specifically its Python implementation directory, for definitive import paths and API usage. Alternatively, consider using `json-e` in a JavaScript context if that aligns with project needs.","message":"The `json-e` PyPI package exists, but its official usage documentation (json-e.js.org) is primarily JavaScript-centric. Direct, high-level Python API usage examples and import paths for explicit JSON-e templating functions are not easily found in public documentation. Users may find themselves defaulting to Python's built-in `json` module for general JSON handling, which does not provide JSON-e's templating capabilities.","severity":"gotcha","affected_versions":"All versions"},{"fix":"Be clear about the distinct purposes: use Python's `json` module for basic JSON parsing/serialization, and investigate the specific `json-e` implementation (if available and documented) when data-structure templating is required. If a dedicated Python `json-e` library with a clear API is not found, a custom solution for templating might be needed or consider other templating engines.","message":"When working with JSON data in Python, it's a common mistake to confuse `json-e` (a templating system) with Python's built-in `json` module. The `json` module handles serialization and deserialization but does not offer the advanced data-structure parameterization features like `$eval`, `$if`, or `$map` that are central to JSON-e's specification.","severity":"gotcha","affected_versions":"All versions"},{"fix":"Always review the `CHANGELOG.rst` in the `json-e` GitHub repository before upgrading major versions. Thoroughly test existing `json-e` templates and their Python processing logic after any upgrade to ensure continued compatibility.","message":"The `json-e` project follows semantic versioning, and breaking changes to the language specification or its implementations (including Python) are possible, though stated to be uncommon and typically result from bug fixes. These changes could arise if a bug fix introduces backward incompatibility, necessitating a major version bump.","severity":"breaking","affected_versions":"Across major versions (e.g., v3.x to v4.x)"}],"env_vars":null,"last_verified":"2026-04-12T00:00:00.000Z","next_check":"2026-07-11T00:00:00.000Z"}