✨ Added templating system

README.md

@@ -44,7 +44,22 @@ const { withError } = require("@moducate/houston");
 const app = require("express")();
 
 app.get("/not-found", (_, res) => {
-  return withError(res, { type: "https://example.com/not-found", status: 404 })
+  return withError(res, { type: "https://example.com/not-found", status: 404 });
+});
+```
+
+## 📄 Templates
+
+You can create error templates using the exported `withTemplate` function:
+
+```js
+const { withTemplate } = require("@moducate/houston");
+const app = require("express")();
+
+const withNotFound = withTemplate({ type: "https://example.com/not-found", status: 404 });
+
+app.get("/not-found", (_, res) => {
+  return withNotFound(res); // The second parameter is optional when using templates
 });
 ```
 

src/index.ts

@@ -48,3 +48,15 @@ export function withError (res: ServerResponse, err: Partial<Error>): void {
   }
   return res.setHeader('Content-Type', mime).end(JSON.stringify(err))
 }
+
+/**
+ * Generates an RFC 7807 compliant error template which can be invoked to
+ * make errors with common values.
+ *
+ * @param template The template's values.
+ * @returns A `withError` function which can be invoked to apply the error
+ * template to a `http.ServerResponse` object.
+ */
+export function withTemplate (template: Partial<Error>): (res: ServerResponse, err?: Partial<Error>) => void {
+  return (res, err) => withError(res, { ...template, ...err })
+}