Add addParameterEnhancer export to client api

lib/client-api/src/client_api.ts

@@ -3,7 +3,13 @@ import { logger } from '@storybook/client-logger';
 import { StoryFn, Parameters } from '@storybook/addons';
 import { toId } from '@storybook/csf';
 
-import { ClientApiParams, DecoratorFunction, ClientApiAddons, StoryApi } from './types';
+import {
+  ClientApiParams,
+  DecoratorFunction,
+  ClientApiAddons,
+  StoryApi,
+  ParameterEnhancer,
+} from './types';
 import { applyHooks } from './hooks';
 import StoryStore from './story_store';
 import { defaultDecorateStory } from './decorators';
@@ -25,6 +31,13 @@ export const addParameters = (parameters: Parameters) => {
   singleton.addParameters(parameters);
 };
 
+export const addParameterEnhancer = (enhancer: ParameterEnhancer) => {
+  if (!singleton)
+    throw new Error(`Singleton client API not yet initialized, cannot call addParameterEnhancer`);
+
+  singleton.addParameterEnhancer(enhancer);
+};
+
 export default class ClientApi {
   private _storyStore: StoryStore;
 
@@ -83,6 +96,10 @@ export default class ClientApi {
     this._storyStore.addGlobalMetadata({ decorators: [], parameters });
   };
 
+  addParameterEnhancer = (enhancer: ParameterEnhancer) => {
+    this._storyStore.addParameterEnhancer(enhancer);
+  };
+
   clearDecorators = () => {
     this._storyStore.clearGlobalDecorators();
   };

lib/client-api/src/index.ts

@@ -1,4 +1,4 @@
-import ClientApi from './client_api';
+import ClientApi, { addDecorator, addParameters, addParameterEnhancer } from './client_api';
 import { defaultDecorateStory } from './decorators';
 import StoryStore from './story_store';
 import ConfigApi from './config_api';
@@ -10,6 +10,9 @@ export * from './hooks';
 
 export {
   ClientApi,
+  addDecorator,
+  addParameters,
+  addParameterEnhancer,
   StoryStore,
   ConfigApi,
   defaultDecorateStory,

lib/client-api/src/story_store.ts

@@ -8,16 +8,16 @@ import stable from 'stable';
 import { Channel } from '@storybook/channels';
 import Events from '@storybook/core-events';
 import { logger } from '@storybook/client-logger';
-import { Comparator, Parameters, StoryFn, StoryContext } from '@storybook/addons';
+import { Comparator, Parameters, Args, StoryFn, StoryContext } from '@storybook/addons';
 import {
   DecoratorFunction,
   StoryMetadata,
   StoreData,
   AddStoryArgs,
   StoreItem,
-  StoryArgs,
   ErrorLike,
   GetStorybookKind,
+  ParameterEnhancer,
 } from './types';
 import { HooksContext } from './hooks';
 import storySort from './storySort';
@@ -34,8 +34,6 @@ interface StoryOptions {
 
 type KindMetadata = StoryMetadata & { order: number };
 
-type ParameterEnhancer = (context: StoryContext) => Parameters;
-
 const isStoryDocsOnly = (parameters?: Parameters) => {
   return parameters && parameters.docsOnly;
 };

lib/client-api/src/types.ts

@@ -21,6 +21,8 @@ export interface StoryMetadata {
   decorators: DecoratorFunction[];
 }
 
+export type ParameterEnhancer = (context: StoryContext) => Parameters;
+
 export interface StoreItem extends StoryContext {
   id: string;
   kind: string;

lib/core/src/server/preview/iframe-webpack.config.js

@@ -46,12 +46,13 @@ export default ({
     if (match) {
       const configFilename = match[1];
       virtualModuleMapping[entryFilename] = `
-        import { addDecorator, addParameters } from '@storybook/${framework}';
+        import { addDecorator, addParameters, addParameterEnhancer } from '@storybook/client-api';
 
-        const { decorators, parameters } = require('${configFilename}');
+        const { decorators, parameters, parameterEnhancers } = require('${configFilename}');
         
         if (decorators) decorators.forEach(decorator => addDecorator(decorator));
         if (parameters) addParameters(parameters);
+        if (parameterEnhancers) parameterEnhancers.forEach(enhancer => addParameterEnhancer(enhancer));
       `;
     }
   });