fix: encode x-www-form-urlencoded examples correctly

fixes #870

Author: RomanHotsiy

src/services/models/Example.ts

@@ -1,7 +1,7 @@
 import { resolve as urlResolve } from 'url';
 
-import { OpenAPIExample, Referenced } from '../../types';
-import { isJsonLike } from '../../utils/openapi';
+import { OpenAPIEncoding, OpenAPIExample, Referenced } from '../../types';
+import { isFormUrlEncoded, isJsonLike, urlFormEncodePayload } from '../../utils/openapi';
 import { OpenAPIParser } from '../OpenAPIParser';
 
 const externalExamplesCache: { [url: string]: Promise<any> } = {};
@@ -12,7 +12,12 @@ export class ExampleModel {
   description?: string;
   externalValueUrl?: string;
 
-  constructor(parser: OpenAPIParser, infoOrRef: Referenced<OpenAPIExample>) {
+  constructor(
+    parser: OpenAPIParser,
+    infoOrRef: Referenced<OpenAPIExample>,
+    mime: string,
+    encoding?: { [field: string]: OpenAPIEncoding },
+  ) {
     const example = parser.deref(infoOrRef);
     this.value = example.value;
     this.summary = example.summary;
@@ -21,6 +26,10 @@ export class ExampleModel {
       this.externalValueUrl = urlResolve(parser.specUrl || '', example.externalValue);
     }
     parser.exitRef(infoOrRef);
+
+    if (isFormUrlEncoded(mime) && this.value && typeof this.value === 'object') {
+      this.value = urlFormEncodePayload(this.value, encoding);
+    }
   }
 
   getExternalValue(mimeType: string): Promise<any> {

src/services/models/MediaType.ts

@@ -30,10 +30,18 @@ export class MediaTypeModel {
     this.schema = info.schema && new SchemaModel(parser, info.schema, '', options);
     this.onlyRequiredInSamples = options.onlyRequiredInSamples;
     if (info.examples !== undefined) {
-      this.examples = mapValues(info.examples, example => new ExampleModel(parser, example));
+      this.examples = mapValues(
+        info.examples,
+        example => new ExampleModel(parser, example, name, info.encoding),
+      );
     } else if (info.example !== undefined) {
       this.examples = {
-        default: new ExampleModel(parser, { value: parser.shalowDeref(info.example) }),
+        default: new ExampleModel(
+          parser,
+          { value: parser.shalowDeref(info.example) },
+          name,
+          info.encoding,
+        ),
       };
     } else if (isJsonLike(name)) {
       this.generateExample(parser, info);
@@ -55,15 +63,25 @@ export class MediaTypeModel {
           sample[this.schema.discriminatorProp] = subSchema.title;
         }
 
-        this.examples[subSchema.title] = new ExampleModel(parser, {
-          value: sample,
-        });
+        this.examples[subSchema.title] = new ExampleModel(
+          parser,
+          {
+            value: sample,
+          },
+          this.name,
+          info.encoding,
+        );
       }
     } else if (this.schema) {
       this.examples = {
-        default: new ExampleModel(parser, {
-          value: Sampler.sample(info.schema, samplerOptions, parser.spec),
-        }),
+        default: new ExampleModel(
+          parser,
+          {
+            value: Sampler.sample(info.schema, samplerOptions, parser.spec),
+          },
+          this.name,
+          info.encoding,
+        ),
       };
     }
   }

src/utils/openapi.ts

@@ -2,6 +2,7 @@ import { dirname } from 'path';
 
 import { OpenAPIParser } from '../services/OpenAPIParser';
 import {
+  OpenAPIEncoding,
   OpenAPIMediaType,
   OpenAPIOperation,
   OpenAPIParameter,
@@ -130,6 +131,101 @@ export function isJsonLike(contentType: string): boolean {
   return contentType.search(/json/i) !== -1;
 }
 
+export function isFormUrlEncoded(contentType: string): boolean {
+  return contentType === 'application/x-www-form-urlencoded';
+}
+
+function formEncodeField(fieldVal: any, fieldName: string, explode: boolean): string {
+  if (!fieldVal || !fieldVal.length) {
+    return fieldName + '=';
+  }
+
+  if (Array.isArray(fieldVal)) {
+    if (explode) {
+      return fieldVal.map(val => `${fieldName}=${val}`).join('&');
+    } else {
+      return fieldName + '=' + fieldVal.map(val => val.toString()).join(',');
+    }
+  } else if (typeof fieldVal === 'object') {
+    if (explode) {
+      return Object.keys(fieldVal)
+        .map(k => `${k}=${fieldVal[k]}`)
+        .join('&');
+    } else {
+      return (
+        fieldName +
+        '=' +
+        Object.keys(fieldVal)
+          .map(k => `${k},${fieldVal[k]}`)
+          .join(',')
+      );
+    }
+  } else {
+    return fieldName + '=' + fieldVal.toString();
+  }
+}
+
+function delimitedEncodeField(fieldVal: any, fieldName: string, delimeter: string): string {
+  if (Array.isArray(fieldVal)) {
+    return fieldVal.map(v => v.toString()).join(delimeter);
+  } else if (typeof fieldVal === 'object') {
+    return Object.keys(fieldVal)
+      .map(k => `${k}${delimeter}${fieldVal[k]}`)
+      .join(delimeter);
+  } else {
+    return fieldName + '=' + fieldVal.toString();
+  }
+}
+
+function deepObjectEncodeField(fieldVal: any, fieldName: string): string {
+  if (Array.isArray(fieldVal)) {
+    console.warn('deepObject style cannot be used with array value:' + fieldVal.toString());
+    return '';
+  } else if (typeof fieldVal === 'object') {
+    return Object.keys(fieldVal)
+      .map(k => `${fieldName}[${k}]=${fieldVal[k]}`)
+      .join('&');
+  } else {
+    console.warn('deepObject style cannot be used with non-object value:' + fieldVal.toString());
+    return '';
+  }
+}
+
+/*
+ * Should be used only for url-form-encoded body payloads
+ * To be used for parmaters should be extended with other style values
+ */
+export function urlFormEncodePayload(
+  payload: object,
+  encoding: { [field: string]: OpenAPIEncoding } = {},
+) {
+  if (Array.isArray(payload)) {
+    throw new Error('Payload must have fields: ' + payload.toString());
+  } else {
+    return Object.keys(payload)
+      .map(fieldName => {
+        const fieldVal = payload[fieldName];
+        const { style = 'form', explode = true } = encoding[fieldName] || {};
+        switch (style) {
+          case 'form':
+            return formEncodeField(fieldVal, fieldName, explode);
+            break;
+          case 'spaceDelimited':
+            return delimitedEncodeField(fieldVal, fieldName, '%20');
+          case 'pipeDelimited':
+            return delimitedEncodeField(fieldVal, fieldName, '|');
+          case 'deepObject':
+            return deepObjectEncodeField(fieldVal, fieldName);
+          default:
+            // TODO implement rest of styles for path parameters
+            console.warn('Incorrect or unsupported encoding style: ' + style);
+            return '';
+        }
+      })
+      .join('&');
+  }
+}
+
 export function langFromMime(contentType: string): string {
   if (contentType.search(/xml/i) !== -1) {
     return 'xml';