add an option to retain unsupported fields

Author: mikunn

README.md

@@ -19,7 +19,7 @@ The purpose of this project is to fill the grap by doing the conversion between
   * for example `type: "dateTime"` becomes `type: "string"` with `format: "date-time"`
 * deletes `nullable` and adds `"null"` to `type` array if `nullable` is `true`
 * supports deep structures with nested `allOf`s etc.
-* removes [OpenAPI specific properties](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.0.md#fixed-fields-20) such as `discriminator`, `deprecated` etc.
+* removes [OpenAPI specific properties](https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.0.md#fixed-fields-20) such as `discriminator`, `deprecated` etc. unless specified otherwise
 * optionally supports `patternProperties` with `x-patternProperties` in the Schema Object
 
 **NOTE**: `$ref`s are not dereferenced. Use a dereferencer such as [json-schema-ref-parser](https://www.npmjs.com/package/json-schema-ref-parser) prior to using this package.
@@ -96,6 +96,10 @@ prints
 }
 ```
 
+#### `keepNotSupported` (array)
+
+By default, the following fields are removed from the result schema: `nullable`, `discriminator`, `readOnly`, `writeOnly`, `xml`, `externalDocs`, `example` and `deprecated` as they are not supported by JSON Schema Draft 4. Provide an array of the ones you want to keep (as strings) and they won't be removed. 
+
 #### `supportPatternProperties` (boolean)
 
 If set to `true` and `x-patternProperties` property is present, change `x-patternProperties` to `patternProperties` and call `patternPropertiesHandler`. If `patternPropertiesHandler` is not defined, call the default handler. See `patternPropertiesHandler` for more information.

index.js

@@ -3,21 +3,24 @@ var deepEqual = require('deep-equal');
 module.exports = convert;
 
 function convert(schema, options) {
+	var notSupported = [
+		'nullable', 'discriminator', 'readOnly',
+		'writeOnly', 'xml', 'externalDocs',
+		'example', 'deprecated'
+	];
+
 	options = options || {};
 	options.dateToDateTime = options.dateToDateTime || false;
 	options.cloneSchema = options.cloneSchema == false ? false : true;
 	options.supportPatternProperties = options.supportPatternProperties || false;
+	options.keepNotSupported = options.keepNotSupported || [];
 
 	if (typeof options.patternPropertiesHandler !== 'function') {
 		options.patternPropertiesHandler = patternPropertiesHandler;
 	}
 
 	options._structs = ['allOf', 'anyOf', 'oneOf', 'not', 'items', 'additionalProperties'];
-	options._notSupported = [
-		'nullable', 'discriminator', 'readOnly', 
-		'writeOnly', 'xml', 'externalDocs',
-		'example', 'deprecated'
-	];
+	options._notSupported = resolveNotSupported(notSupported, options.keepNotSupported);
 
 	if (options.cloneSchema) {
 		schema = JSON.parse(JSON.stringify(schema));
@@ -173,3 +176,19 @@ function patternPropertiesHandler(schema) {
 
 	return schema;
 }
+
+function resolveNotSupported(notSupported, toRetain) {
+	var i = 0
+		, index
+	;
+
+	for(i; i < toRetain.length; i++) {
+		index = notSupported.indexOf(toRetain[i]);
+
+		if (index >= 0) {
+			notSupported.splice(index, 1);
+		}
+	}
+
+	return notSupported;
+}

test/unsupported_properties.js

@@ -2,7 +2,7 @@ var test = require('tape')
 	, convert = require('../')
 ;
 
-test('remove discriminator', function(assert) {
+test('remove discriminator by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -65,7 +65,7 @@ test('remove discriminator', function(assert) {
 	assert.deepEqual(result, expected, 'discriminator removed');
 });
 
-test('remove readOnly', function(assert) {
+test('remove readOnly by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -97,7 +97,7 @@ test('remove readOnly', function(assert) {
 	assert.deepEqual(result, expected, 'readOnly removed');
 });
 
-test('remove writeOnly', function(assert) {
+test('remove writeOnly by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -132,7 +132,7 @@ test('remove writeOnly', function(assert) {
 	assert.deepEqual(result, expected, 'writeOnly removed');
 });
 
-test('remove xml', function(assert) {
+test('remove xml by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -167,7 +167,7 @@ test('remove xml', function(assert) {
 	assert.deepEqual(result, expected, 'xml removed');
 });
 
-test('remove externalDocs', function(assert) {
+test('remove externalDocs by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -202,7 +202,7 @@ test('remove externalDocs', function(assert) {
 	assert.deepEqual(result, expected, 'externalDocs removed');
 });
 
-test('remove example', function(assert) {
+test('remove example by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -225,7 +225,7 @@ test('remove example', function(assert) {
 	assert.deepEqual(result, expected, 'example removed');
 });
 
-test('remove deprecated', function(assert) {
+test('remove deprecated by default', function(assert) {
 	var schema
 		, result
 		, expected
@@ -247,3 +247,58 @@ test('remove deprecated', function(assert) {
 
 	assert.deepEqual(result, expected, 'deprecated removed');
 });
+
+test('retaining fields', function(assert) {
+	var schema
+		, result
+		, expected
+	;
+
+	assert.plan(1);
+
+	schema = {
+		type: 'object',
+		properties: {
+			readOnly: {
+				type: 'string',
+				readOnly: true,
+				example: 'foo'
+			},
+			anotherProp: {
+				type: 'object',
+				properties: {
+					writeOnly: {
+						type: 'string',
+						writeOnly: true
+					}
+				}
+			}
+		},
+		discriminator: 'bar'
+	};
+
+	result = convert(schema, { keepNotSupported: ['readOnly', 'discriminator'] });
+
+	expected = {
+		$schema: 'http://json-schema.org/draft-04/schema#',
+		type: 'object',
+		properties: {
+			readOnly: {
+				type: 'string',
+				readOnly: true,
+			},
+			anotherProp: {
+				type: 'object',
+				properties: {
+					writeOnly: {
+						type: 'string',
+					}
+				}
+			}
+		},
+		discriminator: 'bar'
+	};
+
+	assert.deepEqual(result, expected, 'example and writeOnly removed');
+});
+