Requests for comment/JSON validation
JSON validation | |
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Component | General |
Creation date | |
Author(s) | Legoktm, James Hare |
Document status | in draft See Phabricator. |
This request for comments discusses JSON validation.
Background
[edit]As we increasingly store content in JSON, usually via ContentHandler, there is a need for a standardized JSON validation system that meets the requirements of Wikimedia projects. We currently have two different solutions deployed to the Wikimedia cluster: the JsonSchema class bundled in the EventLogging extension, and the json-schema library that is a development dependency of MediaWiki core and included in the mediawiki/vendor
repository.
Problem
[edit]We are using multiple validators in production, neither of which is suitable for our needs. Each has something the other does not: while the EventLogging schema validator supports localizable error messages, it does not support JSON schema v4 features (test suite). The json-schema library included in core has the opposite problem. This will grow as a problem as more extensions are developed to make use of ContentHandler functionality and there is an inconsistent practice as the tradeoff is made between sophisticated schema and multilingual support.
Proposal
[edit]Based on an agreed-upon set of requirements, we should adopt a schema validator and implement it in MediaWiki core.
Requirements
[edit]These are the current proposed requirements:
- Support for localized error messages (i18n)
- Compliance with JSON Schema Version 4, maybe version 3 as well if there are compatibility issues
- Who needs this and why? Is v4 a draft spec? When will it be finalized and are people expected to support it before finalization?
- For example, the extension.json schema uses features like "anyOf". Yes, it's a draft spec, and there are already implementations that support the draft spec. Legoktm (talk) 05:01, 3 October 2016 (UTC)
- Who needs this and why? Is v4 a draft spec? When will it be finalized and are people expected to support it before finalization?
- Direct support for validating PHP objects/arrays, so they don't need to be converted into JSON first
- Why? Is PHP special?
- The main purpose is that we only parse the JSON once, where it is converted into a PHP object/array. Then if it is valid JSON, it gets passed to the validator which checks the properties/values/etc. but we don't want to have to reparse the JSON again, so it should be able to use the PHP object/array that we already parsed. Legoktm (talk) 05:01, 3 October 2016 (UTC)
- How about passing in the JSON string and validate that? It would make the validator language-agnostic, wouldn't it? Mobrovac-WMF (talk) 14:53, 3 October 2016 (UTC)
- Why? Is PHP special?
Options
[edit]Name | Author | Link | MediaWiki usage | Pros | Cons |
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JsonSchema | RobLa | Bundled inside EventLogging extension |
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json-schema | Justin Rainbow | https://github.com/justinrainbow/json-schema |
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jsonguard | PHP League | https://github.com/thephpleague/json-guard/ | (Not used AFAIK. Wasn't considered during extension.json implementation due to PHP 5.5 requirement) |
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