Add option to generate TS string enums

README.md

@@ -138,6 +138,7 @@ 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)? |
+| inferStringEnumKeysFromValues | boolean | `false` | Create enums from JSON enums with eponymous keys |
 | format | boolean | `true` | Format code? Set this to `false` to improve performance. |
 | ignoreMinAndMaxItems | boolean | `false` | Ignore maxItems and minItems for `array` types, preventing tuples being generated. |
 | maxItems | number | `20` | Maximum number of unioned tuples to emit when representing bounded-size array types, before falling back to emitting unbounded arrays. Increase this to improve precision of emitted types, decrease it to improve performance, or set it to `-1` to ignore `maxItems`.

src/cli.ts

@@ -183,6 +183,8 @@ Boolean values can be set to false using the 'no-' prefix.
       Declare external schemas referenced via '$ref'?
   --enableConstEnums
       Prepend enums with 'const'?
+  --inferStringEnumKeysFromValues
+      Create enums from JSON enums instead of union types
   --format
       Format code? Set this to false to improve performance.
   --maxItems

src/index.ts

@@ -48,6 +48,10 @@ export interface Options {
    * Prepend enums with [`const`](https://www.typescriptlang.org/docs/handbook/enums.html#computed-and-constant-members)?
    */
   enableConstEnums: boolean
+  /**
+   * Create enums from JSON enums with eponymous keys
+   */
+  inferStringEnumKeysFromValues: boolean
   /**
    * Format code? Set this to `false` to improve performance.
    */
@@ -95,6 +99,7 @@ export const DEFAULT_OPTIONS: Options = {
   cwd: process.cwd(),
   declareExternallyReferenced: true,
   enableConstEnums: true,
+  inferStringEnumKeysFromValues: false,
   format: true,
   ignoreMinAndMaxItems: false,
   maxItems: 20,

src/normalizer.ts

@@ -22,6 +22,9 @@ function isObjectType(schema: LinkedJSONSchema) {
 function isArrayType(schema: LinkedJSONSchema) {
   return schema.items !== undefined || hasType(schema, 'array') || hasType(schema, 'any')
 }
+function isEnumTypeWithoutTsEnumNames(schema: LinkedJSONSchema) {
+  return schema.type === 'string' && schema.enum !== undefined && schema.tsEnumNames === undefined
+}
 
 rules.set('Remove `type=["null"]` if `enum=[null]`', schema => {
   if (
@@ -222,6 +225,12 @@ rules.set('Transform const to singleton enum', schema => {
   }
 })
 
+rules.set('Add tsEnumNames to enum types', (schema, _, options) => {
+  if (isEnumTypeWithoutTsEnumNames(schema) && options.inferStringEnumKeysFromValues) {
+    schema.tsEnumNames = schema.enum?.map(String)
+  }
+})
+
 export function normalize(
   rootSchema: LinkedJSONSchema,
   dereferencedPaths: DereferencedPaths,

test/__snapshots__/test/test.ts.md

@@ -1027,6 +1027,33 @@ Generated by [AVA](https://avajs.dev).
       | [{foo: [4, 6]}];␊
     `
 
+## enum.5.js
+
+> Expected output to match snapshot for e2e test: enum.5.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 Enum {␊
+      stringEnum: StringEnum;␊
+      impliedStringEnum: "a" | "b" | "c";␊
+      booleanEnum: true;␊
+      impliedBooleanEnum: true;␊
+      integerEnum: -1 | 0 | 1;␊
+      impliedIntegerEnum: -1 | 0 | 1;␊
+    }␊
+    ␊
+    export const enum StringEnum {␊
+      a = "a",␊
+      b = "b",␊
+      c = "c"␊
+    }␊
+    `
+
 ## enum.js
 
 > Expected output to match snapshot for e2e test: enum.js
@@ -449547,26 +449574,6 @@ Generated by [AVA](https://avajs.dev).
     }␊
     `
 
-> Snapshot 5
-
-    './test/resources/MultiSchema/out/b.yaml.d.ts'
-
-> Snapshot 6
-
-    `/* 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 BSchema {␊
-      x?: string;␊
-      y: number;␊
-      [k: string]: unknown;␊
-    }␊
-    `
-
 ## files in (-i), pipe out
 
 > Snapshot 1

test/e2e/enum.5.ts

@@ -0,0 +1,46 @@
+export const input = {
+  title: 'Enum',
+  type: 'object',
+  definitions: {
+    enumFromDefinition: {
+      type: 'string',
+      enum: ['a', 'b', 'c'],
+    },
+  },
+  properties: {
+    stringEnum: {
+      type: 'string',
+      enum: ['a', 'b', 'c'],
+    },
+    impliedStringEnum: {
+      enum: ['a', 'b', 'c'],
+    },
+    booleanEnum: {
+      type: 'boolean',
+      enum: [true],
+    },
+    impliedBooleanEnum: {
+      enum: [true],
+    },
+    integerEnum: {
+      type: 'integer',
+      enum: [-1, 0, 1],
+    },
+    impliedIntegerEnum: {
+      enum: [-1, 0, 1],
+    }
+  },
+  required: [
+    'stringEnum',
+    'impliedStringEnum',
+    'booleanEnum',
+    'impliedBooleanEnum',
+    'integerEnum',
+    'impliedIntegerEnum'
+  ],
+  additionalProperties: false,
+}
+
+export const options = {
+  inferStringEnumKeysFromValues: true
+}

test/normalizer/addTsEnumNames.1.json

@@ -0,0 +1,17 @@
+{
+  "name": "Add tsEnumNames to enum types (1)",
+  "in": {
+    "$id": "foo",
+    "type": "string",
+    "enum": ["foo", "bar"]
+  },
+  "options": {
+    "inferStringEnumKeysFromValues": true
+  },
+  "out": {
+    "$id": "foo",
+    "type": "string",
+    "enum": [ "foo", "bar" ],
+    "tsEnumNames": ["foo", "bar"]
+  }
+}

test/normalizer/addTsEnumNames.2.json

@@ -0,0 +1,16 @@
+{
+  "name": "Add tsEnumNames to enum types (2)",
+  "in": {
+    "$id": "foo",
+    "type": "string",
+    "enum": ["foo", "bar"]
+  },
+  "options": {
+    "inferStringEnumKeysFromValues": false
+  },
+  "out": {
+    "$id": "foo",
+    "type": "string",
+    "enum": [ "foo", "bar" ]
+  }
+}

test/normalizer/addTsEnumNames.3.json

@@ -0,0 +1,18 @@
+{
+  "name": "Add tsEnumNames to enum types (3)",
+  "in": {
+    "$id": "foo",
+    "type": "string",
+    "enum": ["foo", "bar"],
+    "tsEnumNames": ["FOO", "BAR"]
+  },
+  "options": {
+    "inferStringEnumKeysFromValues": true
+  },
+  "out": {
+    "$id": "foo",
+    "type": "string",
+    "enum": [ "foo", "bar" ],
+    "tsEnumNames": ["FOO", "BAR"]
+  }
+}