fix: default style and explode for params

fixes #1016

src/services/__tests__/fixtures/fields.json

@@ -17,6 +17,21 @@
         "schema": { "type": "array" },
         "style": "form",
         "explode": true
+      },
+      "queryParamWithNoStyle": {
+        "in": "query",
+        "name": "serialization_test_name",
+        "schema": { "type": "array" }
+      },
+      "pathParamWithNoStyle": {
+        "in": "path",
+        "name": "serialization_test_name",
+        "schema": { "type": "array" }
+      },
+      "cookieParamWithNoStyle": {
+        "in": "cookie",
+        "name": "serialization_test_name",
+        "schema": { "type": "array" }
       }
     },
     "headers": {

src/services/__tests__/models/FieldModel.test.ts

@@ -43,6 +43,57 @@ describe('Models', () => {
       expect(field.explode).toEqual(true);
     });
 
+    test('field details relevant for default path param serialization', () => {
+      const field = new FieldModel(
+        parser,
+        {
+          $ref: '#/components/parameters/pathParamWithNoStyle',
+        },
+        '#/components/parameters/pathParamWithNoStyle',
+        opts,
+      );
+
+      expect(field.name).toEqual('serialization_test_name');
+      expect(field.in).toEqual('path');
+      expect(field.schema.type).toEqual('array');
+      expect(field.style).toEqual('simple');
+      expect(field.explode).toEqual(false);
+    });
+
+    test('field details relevant for default query parameter serialization', () => {
+      const field = new FieldModel(
+        parser,
+        {
+          $ref: '#/components/parameters/queryParamWithNoStyle',
+        },
+        '#/components/parameters/queryParamWithNoStyle',
+        opts,
+      );
+
+      expect(field.name).toEqual('serialization_test_name');
+      expect(field.in).toEqual('query');
+      expect(field.schema.type).toEqual('array');
+      expect(field.style).toEqual('form');
+      expect(field.explode).toEqual(true);
+    });
+
+    test('field details relevant for default cookie parameter serialization', () => {
+      const field = new FieldModel(
+        parser,
+        {
+          $ref: '#/components/parameters/queryParamWithNoStyle',
+        },
+        '#/components/parameters/queryParamWithNoStyle',
+        opts,
+      );
+
+      expect(field.name).toEqual('serialization_test_name');
+      expect(field.in).toEqual('query');
+      expect(field.schema.type).toEqual('array');
+      expect(field.style).toEqual('form');
+      expect(field.explode).toEqual(true);
+    });
+
     test('field name should populated from name even if $ref (headers)', () => {
       const field = new FieldModel(
         parser,

src/services/models/Field.ts

@@ -12,18 +12,27 @@ import { extractExtensions } from '../../utils/openapi';
 import { OpenAPIParser } from '../OpenAPIParser';
 import { SchemaModel } from './Schema';
 
-function getDefaultStyleValue(parameterLocation: OpenAPIParameterLocation): OpenAPIParameterStyle {
-  switch (parameterLocation) {
-    case 'header':
-      return 'simple';
-    case 'query':
-      return 'form';
-    case 'path':
-      return 'simple';
-    default:
-      return 'form';
-  }
-}
+const DEFAULT_SERIALIZATION: Record<
+  OpenAPIParameterLocation,
+  { explode: boolean; style: OpenAPIParameterStyle }
+> = {
+  path: {
+    style: 'simple',
+    explode: false,
+  },
+  query: {
+    style: 'form',
+    explode: true,
+  },
+  header: {
+    style: 'simple',
+    explode: false,
+  },
+  cookie: {
+    style: 'form',
+    explode: true,
+  },
+};
 
 /**
  * Field or Parameter model ready to be used by components
@@ -75,10 +84,14 @@ export class FieldModel {
     } else if (info.style) {
       this.style = info.style;
     } else if (this.in) {
-      this.style = getDefaultStyleValue(this.in);
+      this.style = DEFAULT_SERIALIZATION[this.in].style;
     }
 
-    this.explode = !!info.explode;
+    if (info.explode === undefined && this.in) {
+      this.explode = DEFAULT_SERIALIZATION[this.in].explode;
+    } else {
+      this.explode = !!info.explode;
+    }
 
     this.deprecated = info.deprecated === undefined ? !!this.schema.deprecated : info.deprecated;
     parser.exitRef(infoOrRef);