Use JSON Schema to define and document MermaidConfig

.eslintrc.cjs

@@ -38,6 +38,10 @@ module.exports = {
     'lodash',
     'unicorn',
   ],
+  ignorePatterns: [
+    // this file is automatically generated by `pnpm run --filter mermaid types:build-config`
+    'packages/mermaid/src/config.type.ts',
+  ],
   rules: {
     curly: 'error',
     'no-console': 'error',

.github/workflows/lint.yml

@@ -53,6 +53,19 @@ jobs:
               exit 1
           fi
 
+      - name: Verify `./src/config.type.ts` is in sync with `./src/schemas/config.schema.yaml`
+        shell: bash
+        run: |
+          if ! pnpm run --filter mermaid types:verify-config; then
+            ERROR_MESSAGE='Running `pnpm run --filter mermaid types:verify-config` failed.'
+            ERROR_MESSAGE+=' This should be fixed by running'
+            ERROR_MESSAGE+=' `pnpm run --filter mermaid types:build-config`'
+            ERROR_MESSAGE+=' on your local machine.'
+            echo "::error title=Lint failure::${ERROR_MESSAGE}"
+              # make sure to return an error exitcode so that GitHub actions shows a red-cross
+              exit 1
+          fi
+
       - name: Verify Docs
         id: verifyDocs
         working-directory: ./packages/mermaid

.prettierignore

@@ -7,3 +7,5 @@ pnpm-lock.yaml
 stats
 packages/mermaid/src/docs/.vitepress/components.d.ts
 .nyc_output
+# Autogenerated by `pnpm run --filter mermaid types:build-config`
+packages/mermaid/src/config.type.ts

.vite/build.ts

@@ -2,6 +2,7 @@ import { build, InlineConfig, type PluginOption } from 'vite';
 import { resolve } from 'path';
 import { fileURLToPath } from 'url';
 import jisonPlugin from './jisonPlugin.js';
+import jsonSchemaPlugin from './jsonSchemaPlugin.js';
 import { readFileSync } from 'fs';
 import typescript from '@rollup/plugin-typescript';
 import { visualizer } from 'rollup-plugin-visualizer';
@@ -121,6 +122,7 @@ export const getBuildConfig = ({ minify, core, watch, entryName }: BuildOptions)
     },
     plugins: [
       jisonPlugin(),
+      jsonSchemaPlugin(), // handles `.schema.yaml` files
       // @ts-expect-error According to the type definitions, rollup plugins are incompatible with vite
       typescript({ compilerOptions: { declaration: false } }),
       istanbul({

.vite/jsonSchemaPlugin.ts

@@ -0,0 +1,150 @@
+import { load, JSON_SCHEMA } from 'js-yaml';
+import assert from 'node:assert';
+import Ajv2019, { type JSONSchemaType } from 'ajv/dist/2019.js';
+import { PluginOption } from 'vite';
+
+import type { MermaidConfig, BaseDiagramConfig } from '../packages/mermaid/src/config.type.js';
+
+/**
+ * All of the keys in the mermaid config that have a mermaid diagram config.
+ */
+const MERMAID_CONFIG_DIAGRAM_KEYS = [
+  'flowchart',
+  'sequence',
+  'gantt',
+  'journey',
+  'class',
+  'state',
+  'er',
+  'pie',
+  'quadrantChart',
+  'requirement',
+  'mindmap',
+  'timeline',
+  'gitGraph',
+  'c4',
+  'sankey',
+] as const;
+
+/**
+ * Generate default values from the JSON Schema.
+ *
+ * AJV does not support nested default values yet (or default values with $ref),
+ * so we need to manually find them (this may be fixed in ajv v9).
+ *
+ * @param mermaidConfigSchema - The Mermaid JSON Schema to use.
+ * @returns The default mermaid config object.
+ */
+function generateDefaults(mermaidConfigSchema: JSONSchemaType<MermaidConfig>) {
+  const ajv = new Ajv2019({
+    useDefaults: true,
+    allowUnionTypes: true,
+    strict: true,
+  });
+
+  ajv.addKeyword({
+    keyword: 'meta:enum', // used by jsonschema2md
+    errors: false,
+  });
+  ajv.addKeyword({
+    keyword: 'tsType', // used by json-schema-to-typescript
+    errors: false,
+  });
+
+  // ajv currently doesn't support nested default values, see https://github.com/ajv-validator/ajv/issues/1718
+  // (may be fixed in v9) so we need to manually use sub-schemas
+  const mermaidDefaultConfig = {};
+
+  assert.ok(mermaidConfigSchema.$defs);
+  const baseDiagramConfig = mermaidConfigSchema.$defs.BaseDiagramConfig;
+
+  for (const key of MERMAID_CONFIG_DIAGRAM_KEYS) {
+    const subSchemaRef = mermaidConfigSchema.properties[key].$ref;
+    const [root, defs, defName] = subSchemaRef.split('/');
+    assert.strictEqual(root, '#');
+    assert.strictEqual(defs, '$defs');
+    const subSchema = {
+      $schema: mermaidConfigSchema.$schema,
+      $defs: mermaidConfigSchema.$defs,
+      ...mermaidConfigSchema.$defs[defName],
+    } as JSONSchemaType<BaseDiagramConfig>;
+
+    const validate = ajv.compile(subSchema);
+
+    mermaidDefaultConfig[key] = {};
+
+    for (const required of subSchema.required ?? []) {
+      if (subSchema.properties[required] === undefined && baseDiagramConfig.properties[required]) {
+        mermaidDefaultConfig[key][required] = baseDiagramConfig.properties[required].default;
+      }
+    }
+    if (!validate(mermaidDefaultConfig[key])) {
+      throw new Error(
+        `schema for subconfig ${key} does not have valid defaults! Errors were ${JSON.stringify(
+          validate.errors,
+          undefined,
+          2
+        )}`
+      );
+    }
+  }
+
+  const validate = ajv.compile(mermaidConfigSchema);
+
+  if (!validate(mermaidDefaultConfig)) {
+    throw new Error(
+      `Mermaid config JSON Schema does not have valid defaults! Errors were ${JSON.stringify(
+        validate.errors,
+        undefined,
+        2
+      )}`
+    );
+  }
+
+  return mermaidDefaultConfig;
+}
+
+/**
+ * Vite plugin that handles JSON Schemas saved as a `.schema.yaml` file.
+ *
+ * Use `my-example.schema.yaml?only-defaults=true` to only load the default values.
+ */
+export default function jsonSchemaPlugin(): PluginOption {
+  return {
+    name: 'json-schema-plugin',
+    transform(src: string, id: string) {
+      const idAsUrl = new URL(id, 'file:///');
+
+      if (!idAsUrl.pathname.endsWith('schema.yaml')) {
+        return;
+      }
+
+      if (idAsUrl.searchParams.get('only-defaults')) {
+        const jsonSchema = load(src, {
+          filename: idAsUrl.pathname,
+          // only allow JSON types in our YAML doc (will probably be default in YAML 1.3)
+          // e.g. `true` will be parsed a boolean `true`, `True` will be parsed as string `"True"`.
+          schema: JSON_SCHEMA,
+        }) as JSONSchemaType<MermaidConfig>;
+        return {
+          code: `export default ${JSON.stringify(generateDefaults(jsonSchema), undefined, 2)};`,
+          map: null, // no source map
+        };
+      } else {
+        return {
+          code: `export default ${JSON.stringify(
+            load(src, {
+              filename: idAsUrl.pathname,
+              // only allow JSON types in our YAML doc (will probably be default in YAML 1.3)
+              // e.g. `true` will be parsed a boolean `true`, `True` will be parsed as string `"True"`.
+              schema: JSON_SCHEMA,
+            }),
+            undefined,
+            2
+          )};`,
+          map: null, // provide source map if available
+        };
+      }
+    },
+  };
+}

docs/config/setup/modules/defaultConfig.md

@@ -14,43 +14,20 @@
 
 #### Defined in
 
-[defaultConfig.ts:2300](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/defaultConfig.ts#L2300)
+[defaultConfig.ts:266](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/defaultConfig.ts#L266)
 
 ---
 
 ### default
 
 • `Const` **default**: `Partial`<`MermaidConfig`>
 
-**Configuration methods in Mermaid version 8.6.0 have been updated, to learn more\[[click
-here](8.6.0_docs.md)].**
+Default mermaid configuration options.
 
-## **What follows are config instructions for older versions**
-
-These are the default options which can be overridden with the initialization call like so:
-
-**Example 1:**
-
-```js
-mermaid.initialize({ flowchart: { htmlLabels: false } });
-```
-
-**Example 2:**
-
-```html
-<script>
-  const config = {
-    startOnLoad: true,
-    flowchart: { useMaxWidth: true, htmlLabels: true, curve: 'cardinal' },
-    securityLevel: 'loose',
-  };
-  mermaid.initialize(config);
-</script>
-```
-
-A summary of all options and their defaults is found [here](#mermaidapi-configuration-defaults).
-A description of each option follows below.
+Please see the Mermaid config JSON Schema for the default JSON values.
+Non-JSON JS default values are listed in this file, e.g. functions, or
+`undefined` (explicitly set so that `configKeys` finds them).
 
 #### Defined in
 
-[defaultConfig.ts:33](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/defaultConfig.ts#L33)
+[defaultConfig.ts:16](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/defaultConfig.ts#L16)

package.json

@@ -81,6 +81,7 @@
     "@vitest/coverage-v8": "^0.32.2",
     "@vitest/spy": "^0.32.2",
     "@vitest/ui": "^0.32.2",
+    "ajv": "^8.12.0",
     "concurrently": "^8.0.1",
     "cors": "^2.8.5",
     "coveralls": "^3.1.1",

packages/mermaid/.lintstagedrc.mjs

@@ -4,4 +4,5 @@ export default {
   'src/docs/**': ['pnpm --filter mermaid run docs:build --git'],
   'src/docs.mts': ['pnpm --filter mermaid run docs:build --git'],
   'src/(defaultConfig|config|mermaidAPI).ts': ['pnpm --filter mermaid run docs:build --git'],
+  'src/schemas/config.schema.yaml': ['pnpm --filter mermaid run types:build-config --git'],
 };

packages/mermaid/package.json

@@ -32,6 +32,8 @@
     "docs:dev": "pnpm docs:pre:vitepress && concurrently \"pnpm --filter ./src/vitepress dev\" \"ts-node-esm src/docs.mts --watch --vitepress\"",
     "docs:serve": "pnpm docs:build:vitepress && vitepress serve src/vitepress",
     "docs:spellcheck": "cspell --config ../../cSpell.json \"src/docs/**/*.md\"",
+    "types:build-config": "ts-node-esm --transpileOnly scripts/create-types-from-json-schema.mts",
+    "types:verify-config": "ts-node-esm scripts/create-types-from-json-schema.mts --verify",
     "release": "pnpm build",
     "prepublishOnly": "cpy '../../README.*' ./ --cwd=. && pnpm -w run build"
   },
@@ -74,6 +76,7 @@
     "web-worker": "^1.2.0"
   },
   "devDependencies": {
+    "@adobe/jsonschema2md": "^7.1.4",
     "@types/cytoscape": "^3.19.9",
     "@types/d3": "^7.4.0",
     "@types/d3-sankey": "^0.12.1",
@@ -87,6 +90,7 @@
     "@types/uuid": "^9.0.1",
     "@typescript-eslint/eslint-plugin": "^5.59.0",
     "@typescript-eslint/parser": "^5.59.0",
+    "ajv": "^8.11.2",
     "chokidar": "^3.5.3",
     "concurrently": "^8.0.1",
     "coveralls": "^3.1.1",
@@ -97,6 +101,7 @@
     "jison": "^0.4.18",
     "js-base64": "^3.7.5",
     "jsdom": "^22.0.0",
+    "json-schema-to-typescript": "^11.0.3",
     "micromatch": "^4.0.5",
     "path-browserify": "^1.0.1",
     "prettier": "^2.8.8",
@@ -109,6 +114,7 @@
     "typedoc-plugin-markdown": "^3.15.2",
     "typescript": "^5.0.4",
     "unist-util-flatmap": "^1.0.0",
+    "unist-util-visit": "^4.1.2",
     "vitepress": "^1.0.0-alpha.72",
     "vitepress-plugin-search": "^1.0.4-alpha.20"
   },