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Schema Composition

composeSchema merges multiple schema definitions into one. This is useful for splitting large configurations across files or composing shared base schemas with app-specific extensions.

Usage​

import { defineSchema, composeSchema } from 'dotenv-gad';

const baseSchema = defineSchema({
  NODE_ENV: { type: 'string', default: 'development' },
  LOG_LEVEL: { type: 'string', default: 'info' },
});

const dbSchema = defineSchema({
  DATABASE_URL: { type: 'string', required: true, sensitive: true },
  DATABASE_POOL_SIZE: { type: 'number', default: 10 },
});

const schema = composeSchema(baseSchema, dbSchema);

Merge behavior​

  • Later schemas override earlier ones for duplicate keys.
  • You can pass any number of schemas.
const a = defineSchema({ PORT: { type: 'number', default: 3000 } });
const b = defineSchema({ PORT: { type: 'number', default: 8080 } });

const merged = composeSchema(a, b);
// PORT default is now 8080

Safety​

composeSchema uses Object.create(null) internally and skips __proto__, constructor, and prototype keys to prevent prototype pollution attacks.