feat: add x-explicitMappingOnly extension (#1215)

docs/redoc-vendor-extensions.md

@@ -306,3 +306,37 @@ Player:
     x-additionalPropertiesName: attribute-name
     type: string
 ```
+
+#### x-explicitMappingOnly
+**ATTENTION**: This is ReDoc-specific vendor extension. It won't be supported by other tools.
+
+Extends the `discriminator` property of the schema object.
+
+| Field Name     |	Type	  | Description |
+| :------------- | :------: | :---------- |
+| x-explicitMappingOnly | boolean | limit the discriminator selectpicker to the explicit mappings only |
+
+###### Usage in ReDoc
+ReDoc uses this extension to filter the `discriminator` mappings shown in the selectpicker.
+When set to `true`, the selectpicker will only list the the explicitly defined mappings. When `false`,
+the default behavior is kept, i.e. explicit and implicit mappings will be shown.
+
+###### x-explicitMappingOnly example
+
+
+```yaml
+Pet:
+  type: object
+  required:
+    - name
+    - photoUrls
+  discriminator:
+    propertyName: petType
+    x-explicitMappingOnly: true
+    mapping:
+      cat: "#/components/schemas/Cat"
+      bee: "#/components/schemas/HoneyBee"
+```
+
+Will show in the selectpicker only the items `cat` and `bee`, even though the `Dog` class inherits from
+the `Pet` class.

src/services/models/Schema.ts

@@ -240,6 +240,15 @@ export class SchemaModel {
     }
 
     const mapping = discriminator.mapping || {};
+
+    // Defines if the mapping is exhaustive. This avoids having references
+    // that overlap with the mapping entries
+    let isLimitedToMapping = discriminator['x-explicitMappingOnly'] || false;
+    // if there are no mappings, assume non-exhaustive
+    if (Object.keys(mapping).length === 0) {
+      isLimitedToMapping = false;
+    }
+
     const explicitInversedMapping = {};
     for (const name in mapping) {
       const $ref = mapping[name];
@@ -252,7 +261,7 @@ export class SchemaModel {
       }
     }
 
-    const inversedMapping = { ...implicitInversedMapping, ...explicitInversedMapping };
+    const inversedMapping = isLimitedToMapping ? { ...explicitInversedMapping } : { ...implicitInversedMapping, ...explicitInversedMapping };
 
     const refs: Array<{ $ref; name }> = [];
 

src/types/open-api.d.ts

@@ -144,6 +144,7 @@ export interface OpenAPISchema {
 export interface OpenAPIDiscriminator {
   propertyName: string;
   mapping?: { [name: string]: string };
+  'x-explicitMappingOnly'?: boolean;
 }
 
 export interface OpenAPIMediaType {

src/utils/openapi.ts

@@ -579,6 +579,7 @@ export function isRedocExtension(key: string): boolean {
     'x-tagGroups': true,
     'x-traitTag': true,
     'x-additionalPropertiesName': true,
+    'x-explicitMappingOnly': true,
   };
 
   return key in redocExtensions;