feat: expose default value in hover

src/jsonLanguageService.ts

@@ -74,6 +74,7 @@ export function getLanguageService(params: LanguageServiceParams): LanguageServi
 			jsonSchemaService.clearExternalSchemas();
 			settings.schemas?.forEach(jsonSchemaService.registerExternalSchema.bind(jsonSchemaService));
 			jsonValidation.configure(settings);
+			jsonHover.configure(settings);
 		},
 		resetSchema: (uri: string) => jsonSchemaService.onResourceChange(uri),
 		doValidation: jsonValidation.doValidation.bind(jsonValidation),

src/jsonLanguageTypes.ts

@@ -138,6 +138,17 @@ export interface LanguageSettings {
 	 * A list of known schemas and/or associations of schemas to file names.
 	 */
 	schemas?: SchemaConfiguration[];
+
+	/**
+	 * Settings for hover information.
+	 */
+	hover?: {
+		/**
+		 * If set to true, the default value defined in the schema will be shown in hover information.
+		 * Defaults to false.
+		 */
+		showDefaultValue?: boolean;
+	};
 }
 
 export type SeverityLevel = 'error' | 'warning' | 'ignore';

src/services/jsonHover.ts

@@ -6,18 +6,24 @@
 import * as Parser from '../parser/jsonParser.js';
 import * as SchemaService from './jsonSchemaService.js';
 import { JSONWorkerContribution } from '../jsonContributions.js';
-import { TextDocument, PromiseConstructor, Position, Range, Hover, MarkedString } from '../jsonLanguageTypes.js';
+import { TextDocument, PromiseConstructor, Position, Range, Hover, MarkedString, LanguageSettings } from '../jsonLanguageTypes.js';
 
 export class JSONHover {
 
 	private schemaService: SchemaService.IJSONSchemaService;
 	private contributions: JSONWorkerContribution[];
 	private promise: PromiseConstructor;
+	private showDefaultValue: boolean;
 
 	constructor(schemaService: SchemaService.IJSONSchemaService, contributions: JSONWorkerContribution[] = [], promiseConstructor: PromiseConstructor) {
 		this.schemaService = schemaService;
 		this.contributions = contributions;
 		this.promise = promiseConstructor || Promise;
+		this.showDefaultValue = false;
+	}
+
+	public configure(settings: LanguageSettings): void {
+		this.showDefaultValue = settings.hover?.showDefaultValue === true;
 	}
 
 	public doHover(document: TextDocument, position: Position, doc: Parser.JSONDocument): PromiseLike<Hover | null> {
@@ -67,11 +73,13 @@ export class JSONHover {
 			let title: string | undefined = undefined;
 			let markdownDescription: string | undefined = undefined;
 			let markdownEnumValueDescription: string | undefined = undefined, enumValue: string | undefined = undefined;
+			let defaultValue: any = undefined;
 
 			const matchingSchemas = doc.getMatchingSchemas(schema.schema, node.offset).filter((s) => s.node === node && !s.inverted).map((s) => s.schema);
 			for (const schema of matchingSchemas) {
 				title = title || schema.title;
 				markdownDescription = markdownDescription || schema.markdownDescription || toMarkdown(schema.description);
+				defaultValue = schema.default;
 				if (schema.enum) {
 					const idx = schema.enum.indexOf(Parser.getNodeValue(node));
 					if (schema.markdownEnumDescriptions) {
@@ -104,6 +112,9 @@ export class JSONHover {
 				}
 				result += `\`${toMarkdownCodeBlock(enumValue!)}\`: ${markdownEnumValueDescription}`;
 			}
+			if (this.showDefaultValue && defaultValue !== undefined) {
+				result += `\n\n---\n\nDefault value: \`${JSON.stringify(defaultValue)}\``;
+			}
 			return createHover([result]);
 		});
 	}

src/test/hover.test.ts

@@ -6,19 +6,19 @@
 import * as assert from 'assert';
 import { suite, test } from 'node:test';
 
-import { Hover, Position, TextDocument, getLanguageService, JSONSchema, LanguageServiceParams } from '../jsonLanguageService.js';
+import { Hover, Position, TextDocument, getLanguageService, JSONSchema, LanguageServiceParams, LanguageSettings } from '../jsonLanguageService.js';
 
 suite('JSON Hover', () => {
 
-	async function testComputeInfo(value: string, schema: JSONSchema, position: Position, serviceParams?: LanguageServiceParams): Promise<Hover> {
+	async function testComputeInfo(value: string, schema: JSONSchema, position: Position, languageSettings?: Omit<LanguageSettings, 'schemas'>, serviceParams?: LanguageServiceParams): Promise<Hover> {
 		const uri = 'test://test.json';
 		const schemaUri = "http://myschemastore/test1";
 
 		if (!serviceParams) {
 			serviceParams = { schemaRequestService: requestService };
 		}
 		const service = getLanguageService(serviceParams);
-		service.configure({ schemas: [{ fileMatch: ["*.json"], uri: schemaUri, schema }] });
+		service.configure({ schemas: [{ fileMatch: ["*.json"], uri: schemaUri, schema }], ...languageSettings });
 
 
 		const document = TextDocument.create(uri, 'json', 0, value);
@@ -169,6 +169,61 @@ suite('JSON Hover', () => {
 		});
 	});
 
+	test('Default value', async function () {
+		const schema: JSONSchema = {
+			type: 'object',
+			properties: {
+				'prop1': {
+					type: 'string',
+					description: 'A string property',
+					default: 'myDefault'
+				},
+				'prop2': {
+					type: 'number',
+					default: 42
+				},
+				'prop3': {
+					type: 'object',
+					default: { key: 'value' }
+				},
+				'prop4': {
+					type: 'string',
+					description: 'A string property without default'
+				}
+			}
+		};
+
+		// showDefaultValue not configured (defaults to false) - default value should NOT appear
+		await testComputeInfo('{ "prop1": "val" }', schema, { line: 0, character: 12 }).then(result => {
+			assert.deepEqual(result.contents, ['A string property']);
+		});
+
+		// showDefaultValue: false - default value should NOT appear
+		await testComputeInfo('{ "prop1": "val" }', schema, { line: 0, character: 12 }, { hover: { showDefaultValue: false } }).then(result => {
+			assert.deepEqual(result.contents, ['A string property']);
+		});
+
+		// showDefaultValue: true - default value should appear
+		await testComputeInfo('{ "prop1": "val" }', schema, { line: 0, character: 12 }, { hover: { showDefaultValue: true } }).then(result => {
+			assert.deepEqual(result.contents, ['A string property\n\n---\n\nDefault value: `"myDefault"`']);
+		});
+
+		// showDefaultValue: true, numeric default
+		await testComputeInfo('{ "prop2": 1 }', schema, { line: 0, character: 11 }, { hover: { showDefaultValue: true } }).then(result => {
+			assert.deepEqual(result.contents, ['\n\n---\n\nDefault value: `42`']);
+		});
+
+		// showDefaultValue: true, object default
+		await testComputeInfo('{ "prop3": {} }', schema, { line: 0, character: 11 }, { hover: { showDefaultValue: true } }).then(result => {
+			assert.deepEqual(result.contents, ['\n\n---\n\nDefault value: `{"key":"value"}`']);
+		});
+
+		// showDefaultValue: true, but schema has no default - default value should NOT appear
+		await testComputeInfo('{ "prop4": "val" }', schema, { line: 0, character: 12 }, { hover: { showDefaultValue: true } }).then(result => {
+			assert.deepEqual(result.contents, ['A string property without default']);
+		});
+	});
+
 	test('Contribution descriptions', async function () {
 		const serviceParams: LanguageServiceParams = {
 			contributions: [{
@@ -187,10 +242,10 @@ suite('JSON Hover', () => {
 			}]
 		};
 
-		let result = await testComputeInfo('{ "prop1": [ 1, false ] }', {}, { line: 0, character: 3 }, serviceParams);
+		let result = await testComputeInfo('{ "prop1": [ 1, false ] }', {}, { line: 0, character: 3 }, undefined, serviceParams);
 		assert.deepEqual(result.contents, ['test://test.json: prop1']);
 
-		result = await testComputeInfo('{ "prop1": [ 1, false ] }', {}, { line: 0, character: 13 }, serviceParams);
+		result = await testComputeInfo('{ "prop1": [ 1, false ] }', {}, { line: 0, character: 13 }, undefined, serviceParams);
 		assert.deepEqual(result.contents, ['test://test.json: prop1/0']);
 
 	});