Add option to create string enums based on JSON enums

README.md

@@ -87,6 +87,7 @@ See [server demo](example) and [browser demo](https://github.com/bcherny/json-sc
 | cwd | string | `process.cwd()` | Root directory for resolving [`$ref`](https://tools.ietf.org/id/draft-pbryan-zyp-json-ref-03.html)s |
 | declareExternallyReferenced | boolean | `true` | Declare external schemas referenced via `$ref`? |
 | enableConstEnums | boolean | `true` | Prepend enums with [`const`](https://www.typescriptlang.org/docs/handbook/enums.html#computed-and-constant-members)? |
+| enableStringEnums | boolean | `false` | Create enums from JSON enums with eponymous keys |
 | style | object | `{ bracketSpacing: false,  printWidth: 120,  semi: true,  singleQuote: false,  tabWidth: 2,  trailingComma: 'none',  useTabs: false }` | A [Prettier](https://prettier.io/docs/en/options.html) configuration |
 | unreachableDefinitions | boolean | `false` | Generates code for `definitions` that aren't referenced by the schema. |
 | strictIndexSignatures | boolean | `false` | Append all index signatures with `| undefined` so that they are strictly typed. |

src/cli.ts

@@ -77,6 +77,8 @@ Boolean values can be set to false using the 'no-' prefix.
       Declare external schemas referenced via '$ref'?
   --enableConstEnums
       Prepend enums with 'const'?
+  --enableStringEnums
+      Create enums from JSON enums instead of union types
   --style.XXX=YYY
       Prettier configuration
   --unreachableDefinitions

src/index.ts

@@ -32,6 +32,10 @@ export interface Options {
    * Prepend enums with [`const`](https://www.typescriptlang.org/docs/handbook/enums.html#computed-and-constant-members)?
    */
   enableConstEnums: boolean
+  /**
+   * Generate string enums instead of string union types?
+   */
+  enableStringEnums: boolean
   /**
    * Append all index signatures with `| undefined` so that they are strictly typed.
    *
@@ -63,6 +67,7 @@ export const DEFAULT_OPTIONS: Options = {
   cwd: process.cwd(),
   declareExternallyReferenced: true,
   enableConstEnums: true, // by default, avoid generating code
+  enableStringEnums: false,
   strictIndexSignatures: false,
   style: {
     bracketSpacing: false,

src/parser.ts

@@ -200,6 +200,18 @@ function parseNonLiteral(
         type: 'UNION'
       })
     case 'UNNAMED_ENUM':
+      if (options.enableStringEnums && schema.type === "string") {
+        return set({
+          comment: schema.description,
+          keyName,
+          params: schema.enum!.map((_) => ({
+            ast: parse(_, options, rootSchema, undefined, false, processed, usedNames),
+            keyName: _ as string
+          })),
+          standaloneName: standaloneName(schema, keyName, usedNames)!,
+          type: 'ENUM'
+        })
+      }
       return set({
         comment: schema.description,
         keyName,

test/__snapshots__/test/test.ts.md

@@ -9442,3 +9442,25 @@ Generated by [AVA](https://ava.li).
       [k: string]: string | undefined;␊
     }␊
     `
+
+## enumString.js
+
+> Snapshot 1
+
+    `/* tslint: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 EnumStringTest {␊
+      stringEnum: StringEnum;␊
+    }␊
+    ␊
+    export const enum StringEnum {␊
+      a = "a",␊
+      b = "b",␊
+      c = "c"␊
+    }␊
+    `

test/e2e/enumString.ts

@@ -0,0 +1,16 @@
+export const input = {
+  "title": "enumStringTest",
+  "type": "object",
+  "properties": {
+    "stringEnum": {
+      "type": "string",
+      "enum": ["a", "b", "c"]
+    }
+  },
+  required: ['stringEnum'],
+  additionalProperties: false
+}
+
+export const options = {
+  enableStringEnums: true
+}