add readonly option

README.md

@@ -147,7 +147,7 @@ See [server demo](example) and [browser demo](https://github.com/bcherny/json-sc
 | unknownAny | boolean | `true` | Use `unknown` instead of `any` where possible |
 | unreachableDefinitions | boolean | `false` | Generates code for `$defs` that aren't referenced by the schema. |
 | $refOptions | object | `{}` | [$RefParser](https://github.com/APIDevTools/json-schema-ref-parser) Options, used when resolving `$ref`s |
-
+| readonly | boolean | `false` | Emit all types as `readonly` |
 ## Tests
 
 ```sh

src/cli.ts

@@ -24,6 +24,7 @@ main(
       'strictIndexSignatures',
       'unknownAny',
       'unreachableDefinitions',
+      'readonly',
     ],
     default: DEFAULT_OPTIONS,
     string: ['bannerComment', 'cwd'],
@@ -197,6 +198,8 @@ Boolean values can be set to false using the 'no-' prefix.
       Output unknown type instead of any type
   --unreachableDefinitions
       Generates code for definitions that aren't referenced by the schema
+  --readonly
+      Emits all types as readonly
 `,
   )
 }

src/generator.ts

@@ -305,6 +305,7 @@ function generateInterface(ast: TInterface, options: Options): string {
       .map(
         ([isRequired, keyName, ast, type]) =>
           (hasComment(ast) && !ast.standaloneName ? generateComment(ast.comment, ast.deprecated) + '\n' : '') +
+          (options.readonly ? 'readonly ' : '') +
           escapeKeyName(keyName) +
           (isRequired ? '' : '?') +
           ': ' +

src/index.ts

@@ -85,6 +85,10 @@ export interface Options {
    * Generate unknown type instead of any
    */
   unknownAny: boolean
+  /**
+   * Emit all types as readonly
+   */
+  readonly: boolean
 }
 
 export const DEFAULT_OPTIONS: Options = {
@@ -115,6 +119,7 @@ export const DEFAULT_OPTIONS: Options = {
   },
   unreachableDefinitions: false,
   unknownAny: true,
+  readonly: false,
 }
 
 export function compileFromFile(filename: string, options: Partial<Options> = DEFAULT_OPTIONS): Promise<string> {

test/__snapshots__/test/test.ts.md

@@ -2610,6 +2610,28 @@ Generated by [AVA](https://avajs.dev).
     }␊
     `
 
+## readonly.1.js
+
+> Expected output to match snapshot for e2e test: readonly.1.js
+
+    `/* eslint-disable */␊
+    /**␊
+     * This file was automatically generated by json-schema-to-typescript.␊
+     * DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,␊
+     * and run json-schema-to-typescript to regenerate this file.␊
+     */␊
+    ␊
+    export interface ReadonlyConfiguredToTrue {␊
+      readonly a?: {␊
+        readonly [k: string]: unknown;␊
+      };␊
+      readonly b?: {␊
+        readonly [k: string]: unknown;␊
+      };␊
+      readonly [k: string]: unknown;␊
+    }␊
+    `
+
 ## realWorld.awsQuicksight.js
 
 > Expected output to match snapshot for e2e test: realWorld.awsQuicksight.js

test/e2e/readonly.1.ts

@@ -0,0 +1,21 @@
+export const input = {
+  title: 'Readonly (configured to true)',
+  type: 'object',
+  definitions: {
+    e: {
+      type: 'object',
+    },
+  },
+  properties: {
+    a: {
+      type: 'object',
+    },
+    b: {
+      type: 'object',
+    },
+  },
+}
+
+export const options = {
+  readonly: true,
+}