generate-custom
Generate fake data using custom patterns like regex, enums, formats, and ranges for testing and development needs.
Instructions
Generates fake data following custom patterns, including regex patterns, enums, formats, and ranges
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| count | No | Number of records to generate | |
| patterns | Yes | Map of field names to pattern definitions | |
| locale | No | Locale for generated data (affects format-based patterns) | en |
| seed | No | Optional seed for reproducible generation |
Implementation Reference
- src/tools/generate-custom.ts:99-160 (handler)Handler function for the generate-custom MCP tool. Validates input parameters using Zod, validates patterns, instantiates CustomGenerator, generates the requested number of records, and returns a formatted MCP response with the generated data as JSON resource.export function handleGenerateCustom(args: unknown): Promise<{ content: unknown[] }> { const startTime = Date.now(); try { // Validate and parse arguments const params = GenerateCustomSchema.parse(args); // Validate patterns validatePatterns(params.patterns); // Create generator const generator = new CustomGenerator({ seed: params.seed, locale: params.locale, }); // Generate data const data = params.count === 1 ? [generator.generate({ patterns: params.patterns })] : generator.generateMany(params.count, { patterns: params.patterns }); const generationTimeMs = Date.now() - startTime; // Build response const metadata = { count: data.length, patternCount: Object.keys(params.patterns).length, seed: generator.getSeed(), locale: generator.getLocale(), generationTimeMs, }; const responseText = params.seed ? `Generated ${data.length} custom record${data.length > 1 ? 's' : ''} with seed ${params.seed}` : `Generated ${data.length} custom record${data.length > 1 ? 's' : ''}`; return Promise.resolve({ content: [ { type: 'text', text: responseText, }, { type: 'resource', resource: { uri: 'faker://custom/generated', mimeType: 'application/json', text: JSON.stringify({ data, metadata }, null, 2), }, }, ], }); } catch (error) { if (error instanceof z.ZodError) { throw new Error( `Invalid parameters: ${error.errors.map((e) => `${e.path.join('.')}: ${e.message}`).join(', ')}` ); } throw error; } }
- src/tools/generate-custom.ts:38-51 (schema)Zod validation schema defining the input parameters for the generate-custom tool: count, patterns (record of field to custom pattern), locale, and optional seed.export const GenerateCustomSchema = z.object({ count: z.number().min(1).max(10000).default(1).describe('Number of records to generate'), patterns: z .record(z.string(), CustomPatternSchema) .refine((patterns) => Object.keys(patterns).length > 0, { message: 'At least one pattern must be defined', }) .describe('Map of field names to pattern definitions'), locale: z .nativeEnum(SupportedLocale) .default(SupportedLocale.EN) .describe('Locale for generated data (affects format-based patterns)'), seed: z.number().optional().describe('Optional seed for reproducible generation'), });
- src/index.ts:30-31 (registration)Registration of the generate-custom tool and its handler with the FakerMCPServer.// Register User Story 3 tool: generate-custom server.registerTool(generateCustomTool, handleGenerateCustom);
- src/tools/generate-custom.ts:70-75 (registration)MCP Tool object definition for generate-custom, including name, description, and inputSchema derived from Zod schema.export const generateCustomTool: Tool = { name: 'generate-custom', description: 'Generates fake data following custom patterns, including regex patterns, enums, formats, and ranges', inputSchema: zodToJsonSchema(GenerateCustomSchema) as Tool['inputSchema'], };
- src/tools/generate-custom.ts:176-201 (helper)Helper function to validate all custom patterns in the input before generation, dispatching to type-specific validators.function validatePatterns( patterns: Record<string, { type: PatternType; value: string | string[] | RangePattern }> ): void { for (const [fieldName, pattern] of Object.entries(patterns)) { try { switch (pattern.type) { case PatternType.REGEX: validateRegexPattern(pattern.value as string); break; case PatternType.ENUM: validateEnumPattern(pattern.value as string[]); break; case PatternType.FORMAT: validateFormatPattern(pattern.value as string); break; case PatternType.RANGE: validateRangePattern(pattern.value as RangePattern); break; default: throw new Error(`Unsupported pattern type`); } } catch (error) { throw new Error(`Invalid pattern for field '${fieldName}': ${(error as Error).message}`); } } }