1896 fetching other collections from preview

packages/decap-cms-core/index.d.ts

@@ -541,6 +541,7 @@ declare module 'decap-cms-core' {
   export type PreviewTemplateComponentProps = {
     entry: Map<string, any>;
     collection: Map<string, any>;
+    getCollection: (collectionName: string, slug?: string) => Promise<Map<string, any>[]>;
     widgetFor: (name: any, fields?: any, values?: any, fieldsMetaData?: any) => JSX.Element | null;
     widgetsFor: (name: any) => any;
     getAsset: GetAssetFunction;

packages/decap-cms-core/src/actions/entries.ts

@@ -158,7 +158,7 @@ export function entriesFailed(collection: Collection, error: Error) {
   };
 }
 
-async function getAllEntries(state: State, collection: Collection) {
+export async function getAllEntries(state: State, collection: Collection) {
   const backend = currentBackend(state.config);
   const integration = selectIntegration(state, collection.get('name'), 'listEntries');
   const provider: Backend = integration

packages/decap-cms-core/src/components/Editor/EditorPreviewPane/EditorPreviewPane.js

@@ -13,6 +13,7 @@ import {
   getPreviewStyles,
   getRemarkPlugins,
 } from '../../../lib/registry';
+import { getAllEntries, tryLoadEntry } from '../../../actions/entries';
 import { ErrorBoundary } from '../../UI';
 import {
   selectTemplateName,
@@ -196,6 +197,23 @@ export class PreviewPane extends React.Component {
     });
   };
 
+  /**
+   * This function exists entirely to expose collections from outside of this entry
+   *
+   */
+  getCollection = async (collectionName, slug) => {
+    const { state } = this.props;
+    const selectedCollection = state.collections.get(collectionName);
+
+    if (typeof slug === 'undefined') {
+      const entries = await getAllEntries(state, selectedCollection);
+      return entries.map(entry => Map().set('data', entry.data));
+    }
+
+    const entry = await tryLoadEntry(state, selectedCollection, slug);
+    return Map().set('data', entry.data);
+  };
+
   render() {
     const { entry, collection, config } = this.props;
 
@@ -212,6 +230,7 @@ export class PreviewPane extends React.Component {
       ...this.props,
       widgetFor: this.widgetFor,
       widgetsFor: this.widgetsFor,
+      getCollection: this.getCollection,
     };
 
     const styleEls = getPreviewStyles().map((style, i) => {
@@ -261,7 +280,7 @@ PreviewPane.propTypes = {
 
 function mapStateToProps(state) {
   const isLoadingAsset = selectIsLoadingAsset(state.medias);
-  return { isLoadingAsset, config: state.config };
+  return { isLoadingAsset, config: state.config, state };
 }
 
 function mapDispatchToProps(dispatch) {