JSON Type Definition (RFC8927) to TypeScript compiler.
- Compile enums, interface and types;
- Modify naming of enums, enum keys and values, interfaces, types, properties and any other rendered entities;
- Compile validator functions that produce an array of detected validation errors;
- Validators support recursive structures and shallow checks;
- Compile type narrowing functions aka type guards;
- Create custom validator dialect and have explicit control over every aspect of code generation;
- CLI and programmatic usage;
npm install --save-dev @jtdc/cliBy default, validators and type guards use a @jtdc/jtd-dialect runtime dependency. You can alter validator compiler dialect by providing validatorDialectFactory option to the compiler.
npm install --save-prod @jtdc/jtd-dialectLet's assume you have user and account type definitions in separate files under ./src folder:
./src/user.json
{ "user": { "properties": { "email": {"type": "string"}, "friends": { "elements": {"ref": "user"} } }, "optionalProperties": { "name": {"type": "string"}, "age": {"type": "int8"} } } }./src/account.json
{ "account": { "properties": { "user": {"ref": "./user.json#user"}, "stats": { "properties": { "visitCount": {"type": "int32"} } } }, "optionalProperties": { "roles": { "metadata": { "comment": "The default role is guest" }, "elements": {"ref": "role"} } } }, "role": { "enum": ["admin", "guest"] } }To compile these definitions to TypeScript use this command:
npx jtdc --package @jtdc/cli --rootDir ./src --includes '*.json' --outDir ./src/gen --typeGuardsThe result would be output to ./src/gen folder:
./src/gen/user.ts
import * as runtime from '@jtdc/jtd-dialect/lib/runtime'; export interface User { email: string; friends: Array<User>; name?: string; age?: number; } export let validateUser: runtime.Validator = (a, b, c) => { let d, e, f, g, h; b = b || {}; c = c || ''; if (runtime.checkObject(a, b, c)) { runtime.checkString(a.email, b, c + '/email'); d = a.friends; e = c + '/friends'; if (runtime.checkArray(d, b, e)) { for (f = 0; f < d.length; f++) { validateUser(d[f], b, e + runtime.JSON_POINTER_SEPARATOR + f); } } g = a.name; if (runtime.isDefined(g)) { runtime.checkString(g, b, c + '/name'); } h = a.age; if (runtime.isDefined(h)) { runtime.checkInteger(h, b, c + '/age'); } } return b.errors; }; export let isUser = (value: unknown): value is User => !validateUser(value, {shallow: true});./src/gen/account.ts
import * as runtime from '@jtdc/jtd-dialect/lib/runtime'; import {User, validateUser} from './user'; export interface Account { user: User; stats: { visitCount: number; }; /** * The default role is guest */ roles?: Array<Role>; } export enum Role { ADMIN = 'admin', GUEST = 'guest', } export let validateAccount: runtime.Validator = (a, b, c) => { let d, e, f, g, h; b = b || {}; c = c || ''; if (runtime.checkObject(a, b, c)) { validateUser(a.user, b, c + '/user'); d = a.stats; e = c + '/stats'; if (runtime.checkObject(d, b, e)) { runtime.checkInteger(d.visitCount, b, e + '/visitCount'); } f = a.roles; if (runtime.isDefined(f)) { g = c + '/roles'; if (runtime.checkArray(f, b, g)) { for (h = 0; h < f.length; h++) { validateRole(f[h], b, g + runtime.JSON_POINTER_SEPARATOR + h); } } } } return b.errors; }; export let isAccount = (value: unknown): value is Account => !validateAccount(value, {shallow: true}); export let validateRole: runtime.Validator = (a, b, c) => { b = b || {}; runtime.checkEnum(a, (validateRole.cache ||= {}).a ||= ['admin', 'guest'], b, c || ''); return b.errors; }; export let isRole = (value: unknown): value is Role => !validateRole(value, {shallow: true});You can find the source code of this example here.
import {compileModules} from '@jtdc/compiler'; import userJson from './src/user.json'; import accountJson from './src/account.json'; compileModules({ './user': userJson, './account': accountJson, }); // → {'./user': 'import …', './account': 'import …'}