Convert json schema const values to typescript const values

Resolves bcherny#263

Author: djbeaumont

src/generator.ts

@@ -118,6 +118,7 @@ function declareNamedTypes(
         hasStandaloneName(ast) ? generateStandaloneType(ast, options) : undefined
       ].filter(Boolean).join('\n')
       break
+    case 'CONST':
     case 'ENUM':
       type = ''
       break
@@ -176,6 +177,7 @@ function generateRawType(ast: AST, options: Options): string {
     case 'OBJECT': return 'object'
     case 'REFERENCE': return ast.params
     case 'STRING': return 'string'
+    case 'CONST': return JSON.stringify(ast.params)
     case 'TUPLE': return (() => {
       const minItems = ast.minItems
       const maxItems = ast.maxItems || -1

src/parser.ts

@@ -119,6 +119,14 @@ function parseNonLiteral(
         standaloneName: standaloneName(schema, keyName, usedNames)!,
         type: 'ENUM'
       })
+    case 'CONST':
+      return set({
+        comment: schema.description,
+        keyName,
+        params: schema.const,
+        // standaloneName: standaloneName(schema, keyName, usedNames)!,
+        type: 'CONST'
+      })
     case 'NAMED_SCHEMA':
       return set(newInterface(schema as SchemaSchema, options, rootSchema, processed, usedNames, keyName))
     case 'NULL':

src/typeOfSchema.ts

@@ -14,6 +14,7 @@ export function typeOfSchema(schema: JSONSchema): SCHEMA_TYPE {
   if (schema.enum) return 'UNNAMED_ENUM'
   if (schema.$ref) return 'REFERENCE'
   if (Array.isArray(schema.type)) return 'UNION'
+  if (schema.const) return 'CONST'
   switch (schema.type) {
     case 'string': return 'STRING'
     case 'number': return 'NUMBER'

src/types/AST.ts

@@ -4,7 +4,7 @@ export type AST_TYPE = AST['type']
 
 export type AST = TAny | TArray | TBoolean | TEnum | TInterface | TNamedInterface
   | TIntersection | TLiteral | TNumber | TNull | TObject | TReference
-  | TString | TTuple | TUnion | TCustomType
+  | TString | TTuple | TUnion | TCustomType | TConst
 
 export interface AbstractAST {
   comment?: string
@@ -121,6 +121,11 @@ export interface TCustomType extends AbstractAST {
   params: string
 }
 
+export interface TConst extends AbstractAST {
+  type: 'CONST'
+  params: any
+}
+
 ////////////////////////////////////////////     literals
 
 export const T_ANY: TAny = {

src/types/JSONSchema.ts

@@ -3,7 +3,7 @@ import { JSONSchema4, JSONSchema4TypeName } from 'json-schema'
 export type SCHEMA_TYPE = 'ALL_OF' | 'UNNAMED_SCHEMA' | 'ANY' | 'ANY_OF'
   | 'BOOLEAN' | 'NAMED_ENUM' | 'NAMED_SCHEMA' | 'NULL' | 'NUMBER' | 'STRING'
   | 'OBJECT' | 'ONE_OF' | 'TYPED_ARRAY' | 'REFERENCE' | 'UNION' | 'UNNAMED_ENUM'
-  | 'UNTYPED_ARRAY' | 'CUSTOM_TYPE'
+  | 'UNTYPED_ARRAY' | 'CUSTOM_TYPE' | 'CONST'
 
 export type JSONSchemaTypeName = JSONSchema4TypeName
 

test/__snapshots__/test/test.ts.md

@@ -1072,6 +1072,25 @@ Generated by [AVA](https://ava.li).
     }␊
     `
 
+## const.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 ExampleSchema {␊
+      aString: "foo";␊
+      aNumber: 5;␊
+      aBoolean: true;␊
+      [k: string]: any;␊
+    }␊
+    `
+
 ## customType.js
 
 > Snapshot 1
@@ -9206,6 +9225,23 @@ Generated by [AVA](https://ava.li).
     }␊
     `
 
+## strictIndexSignatures.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 StrictIndexSignatures {␊
+      maybe?: string;␊
+      [k: string]: string | undefined;␊
+    }␊
+    `
+
 ## subSchema.js
 
 > Snapshot 1
@@ -9425,20 +9461,3 @@ Generated by [AVA](https://ava.li).
       [k: string]: any;␊
     }␊
     `
-
-## strictIndexSignatures.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 StrictIndexSignatures {␊
-      maybe?: string;␊
-      [k: string]: string | undefined;␊
-    }␊
-    `

test/__snapshots__/test/test.ts.snap

@@ -0,0 +1,19 @@
+export const input = {
+  title: 'Example Schema',
+  type: 'object',
+  properties: {
+    aString: {
+      type: 'string',
+      const: 'foo'
+    },
+    aNumber: {
+      type: 'number',
+      const: 5
+    },
+    aBoolean: {
+      type: 'boolean',
+      const: true
+    }
+  },
+  required: ['aString', 'aNumber', 'aBoolean']
+}