feat: stringFromSchemaEnv

src/common/schema/env.spec.ts

@@ -1,4 +1,4 @@
-import { parseSchemaEnv } from './env'
+import { parseSchemaEnv, stringFromSchemaEnv } from './env'
 import { boolean, number, object, string } from './schema'
 
 describe('env.spec', () => {
@@ -45,5 +45,11 @@ describe('env.spec', () => {
         "servicePort": 9999,
       }
     `)
+
+    expect(stringFromSchemaEnv(schema, 'APP_', true)).toMatchInlineSnapshot(`
+      "# APP_SERVICE_NAME=generic
+      # APP_SERVICE_PORT=80
+      # APP_SERVICE_FLAG=true"
+    `)
   })
 })

src/common/schema/env.ts

@@ -1,6 +1,6 @@
 import { assert } from '../assert'
 import { objectFilter, objectMap, valueToBoolean, valueToBooleanNotFalse, valueToInteger } from '../data'
-import { toCamelCase } from '../data/camelcase'
+import { fromCamelCase, toCamelCase } from '../data/camelcase'
 import type { Type } from './schema'
 import { isSchemaObjectFlat } from './utils'
 
@@ -35,3 +35,15 @@ export function parseSchemaEnv<T>(schema: Type<T>, env: any = process?.env ?? {}
     return schema.parse(value)
   }) as T
 }
+
+export function stringFromSchemaEnv<T>(schema: Type<T>, prefix = '', commentOut = false): string {
+  assert(isSchemaObjectFlat(schema), 'schema should be a flat object')
+
+  const lines: string[] = []
+
+  objectMap(schema._object!, (key, schema) => {
+    lines.push(`${commentOut ? '# ' : ''}${prefix + fromCamelCase(key, '_').toUpperCase()}=${schema._default ?? ''}`)
+  }) as T
+
+  return lines.join('\n')
+}