New pbundle option "packReduxData" for SSR redux state

packages/subapp-pbundle/lib/framework-lib.js

@@ -132,10 +132,11 @@ class FrameworkLib {
     }
 
     this.initialState = reduxData.initialState || reduxData;
-    // if subapp didn't request to skip sending initial state, then stringify it
-    // and attach it to the index html.
+    const packReduxData = subAppServer.packReduxData || subApp.packReduxData;
 
-    if (subAppServer.attachInitialState !== false) {
+    // if subapp didn't request to skip sending initial state and packReduxData was not specified,
+    //  then stringify the initial store state and attach it to the index html.
+    if (!packReduxData && subAppServer.attachInitialState !== false) {
       this.initialStateStr = JSON.stringify(this.initialState);
     } else {
       this.initialStateStr = "";
@@ -168,11 +169,20 @@ class FrameworkLib {
   }
 
   async realizeReduxStore() {
+    const { subApp, subAppServer } = this.ref;
+
     if (this.store && this.store.realize) {
       this.store = this.store.realize();
       await this.signalStoreReady();
     }
-  }
+
+    const packReduxData = subAppServer.packReduxData || subApp.packReduxData;
+    // if subapp didn't request to skip sending initial state and packReduxData was specified,
+    //  then stringify packReduxData's return value and attach it to the index html.
+    if (packReduxData && !subAppServer.attachInitialState) {
+      this.initialStateStr = JSON.stringify(packReduxData(this.store));
+    }
+}
 
   async signalStoreReady() {
     const reduxStoreReady =

packages/subapp-pbundle/test/spec/ssr-framework.spec.js

@@ -163,9 +163,15 @@ describe("SSR Preact framework", function() {
 
   const helloBundle = {
     name: "hello",
-    reducer(state = "foo") {
+    reducer(state = "foo", action) {
+      if (action.type === "UPDATE_STATE") {
+        return action.newState;
+      }
       return state;
     },
+    doUpdateState: (newState) => ({ dispatch }) => {
+      dispatch({ type: "UPDATE_STATE", newState });
+    },
     selectHello(state) {
       return state.hello;
     }
@@ -354,4 +360,38 @@ describe("SSR Preact framework", function() {
     expect(store).to.equal(false);
     expect(html).to.equal("");
   });
+
+  it("should use packReduxData to generate initial state if it exists", async () => {
+    const framework = new lib.FrameworkLib({
+      subApp: {
+        __redux: true,
+        packReduxData: (store) => store.getState(),
+        reduxStoreReady: ({ store }) => {
+          store.doUpdateState("universe");
+        },
+        reduxCreateStore(initialState) {
+          return {
+            realize() {
+              return composeBundles(helloBundle)(initialState);
+            }
+          };
+        }
+      },
+      subAppServer: {
+        StartComponent: connect("selectHello", ({ hello }) => {
+          return `test hello ${hello}`;
+        }),
+        async prepare() {
+          return { hello: "world" };
+        }
+      },
+      context: {
+        user: {}
+      },
+      options: { serverSideRendering: true }
+    });
+
+    await framework.handleSSR();
+    expect(JSON.parse(framework.initialStateStr).hello).to.equal("universe");
+  });
 });