Vite Plugin

xml-model relies on typescript-rtti for runtime type information. typescript-rtti works by injecting a TypeScript compiler transformer that emits metadata during compilation. The Vite plugin wires this transformer into your Vite build.

Installation

vite and @rollup/plugin-typescript are peer dependencies:

npm install --save-dev vite @rollup/plugin-typescript tslib

Setup

// vite.config.ts
import { defineConfig } from "vite";
import XMLModelPlugin from "xml-model/vite";

export default defineConfig({
  plugins: [...XMLModelPlugin()],
});

XMLModelPlugin() returns an array of plugins. Spread it into plugins.

tsconfig requirement

The plugin requires experimentalDecorators: true and useDefineForClassFields: false in your tsconfig.json. See Getting Started for details.

Options

XMLModelPlugin({
  include: /\.ts$/,       // only transform matching files
  exclude: /node_modules/, // never transform these files
  debug: false,            // print RTTI transformer debug logs
  typescript: { ... },     // options forwarded to @rollup/plugin-typescript
})

include

RegExp — Restrict RTTI transformation to files whose path matches this pattern. When omitted, all files are transformed.

// Only transform application source files, not tests
XMLModelPlugin({ include: /src\/(?!.*\.test\.ts)/ });

exclude

RegExp — Skip RTTI transformation for files whose path matches this pattern. Evaluated before include.

XMLModelPlugin({ exclude: /node_modules/ });

typescript

Options forwarded directly to @rollup/plugin-typescript. Useful for specifying a custom tsconfig path:

XMLModelPlugin({
  typescript: { tsconfig: "./tsconfig.app.json" },
});

WARNING

Do not override the transformers option inside typescript — the plugin uses it to inject the RTTI transformer, and overriding it would break the integration.

debug

boolean (default: false) — When true, prints a log line for each file the RTTI transformer processes.

XMLModelPlugin({ debug: true });
// [RTTI] Transformer is running!
// [RTTI] transforming /path/to/src/models/book.ts

Individual plugins

The plugins composing XMLModelPlugin are also exported individually:

import { FixClassNames, TypescriptRTTI } from "xml-model/vite";

• FixClassNames() — Post-transform plugin that prevents esbuild from mangling class names that the library relies on for tag-name derivation.
• TypescriptRTTI(options) — Applies the typescript-rtti TypeScript transformer via @rollup/plugin-typescript.

Caveats

Monorepo / Vitest workspaces

The RTTI transformer must be loaded by the Vite/Vitest instance that processes your source files. In a monorepo, running vitest from the repo root may not pick up the package-level vite.config.ts, which means the transformer never runs and all runtime type reflection silently returns empty results.

Fix: run vitest from within the package directory, or configure Vitest workspaces so each package uses its own vite.config.ts.

import type and property erasure

typescript-rtti emits metadata by reading TypeScript type information during compilation. If a class used as a property type is imported with import type (or import { type X }), TypeScript erases the import before the transformer runs — leaving the property with no usable type information at runtime.

xml-model will log a warning when it detects this:

[xml-model] Property 'mask' on 'VideoAnalysisFilter' has type Object at runtime.
If its declared type is a class, make sure it is imported as a value and not with 'import type'.

Fix: change import type Foo from "./foo" to import Foo from "./foo" for any class used as a property type.