Add isValidId(): check if a given string is a valid Dato URL-safe Base64-encoded ID

Author: arcataroger

packages/cma-client/__tests__/idUtils.test.ts

@@ -0,0 +1,15 @@
+import { generateId, isValidId } from '../src/idUtils';
+
+describe('generateId', () => {
+  it('expects an ID from generateId() to validate as a DatoCMS ID', () => {
+    expect(isValidId(generateId())).toBe(true);
+  });
+});
+
+describe('isValidId', () => {
+  it('checks if passed string is a valid DatoCMS ID', () => {
+    expect(isValidId('')).toBe(false);
+    expect(isValidId('foobar')).toBe(false);
+    expect(isValidId('WTyssHtyTzu9_EbszSVhPw')).toBe(true);
+  });
+});

packages/cma-client/src/generateId.ts

@@ -0,0 +1,82 @@
+import { v4 } from "uuid";
+
+const decoder = new TextDecoder("utf8");
+
+function fromUint8ArrayToUrlSafeBase64(bytes: Uint8Array) {
+  const base64 =
+    typeof Buffer === "undefined"
+      ? btoa(decoder.decode(bytes))
+      : Buffer.from(bytes).toString("base64");
+
+  // Convert to URL-safe format (see RFC 4648, sec. 5)
+  return (
+    base64
+      // Replace + with -
+      .replace(/\+/g, "-")
+      // Replace / with _
+      .replace(/\//g, "_")
+      // Drop '==' padding
+      .substring(0, 22)
+  );
+}
+
+function fromUrlSafeBase64toUint8Array(urlSafeBase64: string): Uint8Array {
+  // Convert from URL-safe format (see RFC 4648, sec. 5)
+  const base64 = urlSafeBase64
+    // Replace - with +
+    .replace(/-/g, "+")
+    // Replace _ with /
+    .replace(/_/g, "/");
+
+  return typeof Buffer === "undefined"
+    ? Uint8Array.from(atob(base64), (c) => c.charCodeAt(0))
+    : new Uint8Array(Buffer.from(base64, "base64"));
+}
+
+export function isValidId(id: string) {
+  const bytes = fromUrlSafeBase64toUint8Array(id);
+
+  if (bytes.length !== 16) {
+    return false;
+  }
+
+  // The variant field determines the layout of the UUID (see RFC 4122,
+  // sec. 4.1.1)
+
+  const variant = bytes.at(8)!;
+
+  // Variant must be the one described in RFC 4122
+  if ((variant & 0b11000000) !== 0b10000000) {
+    return false;
+  }
+
+  // The version number is in the most significant 4 bits of the time
+  // stamp (see RFC 4122, sec. 4.1.3)
+
+  const version = bytes.at(6)! >> 4;
+
+  // Version number must be 4 (randomly or pseudo-randomly generated)
+  if (version !== 0x4) {
+    return false;
+  }
+
+  return true;
+}
+
+export function generateId() {
+  const bytes = v4(null, new Uint8Array(16));
+
+  // Here we unset the first bit to ensure [A-Za-f] as the first char.
+  //
+  // If we didn't do this, we would generate IDs that, once encoded
+  // in base64, could start with a '+' or a '/'. This makes them less
+  // easy to copy/paste, with bad DX.
+
+  // This choice is purely aesthetic: definitely non-mandatory!
+
+  bytes[0] = bytes[0]! & 0x7f;
+
+  const base64 = fromUint8ArrayToUrlSafeBase64(bytes);
+
+  return base64;
+}

packages/cma-client/src/idUtils.ts

@@ -1,9 +1,9 @@
-export { ApiError, TimeoutError, LogLevel } from '@datocms/rest-client-utils';
+export { ApiError, LogLevel, TimeoutError } from '@datocms/rest-client-utils';
+export * from './buildBlockRecord';
+export * from './buildClient';
 export { Client } from './generated/Client';
-export * as Resources from './generated/resources';
 export type { ClientConfigOptions } from './generated/Client';
-export * from './buildClient';
-export * from './buildBlockRecord';
-export * from './generateId';
+export * as Resources from './generated/resources';
 export * as SchemaTypes from './generated/SchemaTypes';
 export * as SimpleSchemaTypes from './generated/SimpleSchemaTypes';
+export * from './idUtils';