Providing JSON schemas for Foundry VTT module.json / system.json manifests & League of Extraordinary Foundry Developers manifest+ extensions in addition to compiled validator functions. The current manifest+ support is v1.1.0.

There are loose and strict variations for the four schema variations. Loose variations follow the officially posted manifest and manifest plus specifications and only check that types are correct. The strict variations enforce extra rules such as semantic versioning where applicable and other pattern matching aspects to ensure correctness.

JSON Schema / IDE integration

For end developers it is useful to set up the appropriate JSON schema with your IDE. Check these links for IDE info for Webstorm or
VS Code. Point to the relevant JSON schema file found in ./schema and enable intellisense in your IDE. For reference since this is a NPM module you will link ./node_modules/@typhonjs-fvtt/validate-manifest/schema/strict/module+.json. The schema files ending in + include the standard manifest and manifest plus coverage.

There are 8 schemas available:

• ./schema/loose/module.json
• ./schema/loose/module+.json
• ./schema/loose/system.json
• ./schema/loose/system+.json
• ./schema/strict/module.json
• ./schema/strict/module+.json
• ./schema/strict/system.json
• ./schema/strict/system+.json

Foundry VTT tools developers

For Foundry VTT tools developers and anyone needing to validate manifest files. The validator functions are compiled by ajv and are located in the ./dist directory. The main entry point for the NPM module points to the ./dist/validators.js.

There are 8 validator functions:

• validateModule
• validateModuleStrict
• validateModulePlus
• validateModulePlusStrict
• validateSystem
• validateSystemStrict
• validateSystemPlus
• validateSystemPlusStrict

A trivial example of using the validateModule function.

import fs                 from 'fs';

import { validateModule } from '@typhonjs-fvtt/validate-manifest';

const moduleJSONObject = JSON.parse(fs.readFileSync('./src/module.json', 'utf8'););  // load from some location.

if (!validateModule(moduleJSONObject))
{
  console.log(JSON.stringify(validateModule.errors);
}

Please see ajv and ajv-errors for more information about the validator functions and resulting error entries stored in the errors array after a validator function is invoked. Considerable work has been done to ensure that one condition resolves to one error listed in the errors array. There is a comprehensive test suite which covers all possible errors that may occur with data contained in the manifest files.

If you are planning on displaying error information to end users you may want to take a look at the @typhonjs-node-utils/better-ajv-errors module which formats the errors array with user readable messages and associated code frames. An example of using the better-ajv-errors module.

import fs                 from 'fs';

import BetterErrors       from '@typhonjs-node-utils/better-ajv-errors';
import { validateModule } from '@typhonjs-fvtt/validate-manifest';

const moduleJSONFile = fs.readFileSync('./src/module.json', 'utf8');   // load the text string for the manifest.
const moduleJSONObject = JSON.parse(moduleJSONFile);                   // parse the manifest file.

if (!validateModule(moduleJSONObject))
{
   console.log(BetterErrors.asString(validateModule.errors, { file: moduleJSONFile }));
}

###Architecture A very brief overview... The base source schemas is shared across all variations and located in ./src/schema and is compiled / dereferenced into single file loose and strict variations in ./schema by the compile NPM script. There is a custom merge step with template includes found in ./src/schema/merge. These are common definitions which are then combined into the final schema files.

Please reach out and get in touch if you need any more assistance at the issues forum.