From f186cadba6aa6c35e2a0245855550a5f4e2b5c54 Mon Sep 17 00:00:00 2001
From: devneko <dotneet@gmail.com>
Date: Sun, 29 Oct 2017 11:02:48 +0900
Subject: [PATCH] fix unexpected state reset #1408

---
 lib/app/client.js |  9 +++++----
 lib/app/utils.js  | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/lib/app/client.js b/lib/app/client.js
index 3a98e4de58..77b683a535 100644
--- a/lib/app/client.js
+++ b/lib/app/client.js
@@ -6,7 +6,7 @@ import {
   sanitizeComponent,
   resolveRouteComponents,
   getMatchedComponents,
-  getMatchedComponentsInstances,
+  getChangedComponentsInstances,
   flatMapComponents,
   setContext,
   middlewareSeries,
@@ -346,16 +346,17 @@ function showNextPage(to) {
 
 // When navigating on a different route but the same component is used, Vue.js
 // Will not update the instance data, so we have to update $data ourselves
-function fixPrepatch (to, ___) {
+function fixPrepatch (to, from) {
   if (this._hashChanged) return
 
   Vue.nextTick(() => {
-    const instances = getMatchedComponentsInstances(to)
+    const instances = getChangedComponentsInstances(to, from)
 
+    var dlen = to.matched.length - instances.length
     _lastComponentsFiles = instances.map((instance, i) => {
       if (!instance) return '';
 
-      if (_lastPaths[i] === instance.constructor._path && typeof instance.constructor.options.data === 'function') {
+      if (_lastPaths[dlen + i] === instance.constructor._path && typeof instance.constructor.options.data === 'function') {
         const newData = instance.constructor.options.data.call(instance)
         for (let key in newData) {
           Vue.set(instance.$data, key, newData[key])
diff --git a/lib/app/utils.js b/lib/app/utils.js
index 88626ac9f0..52d4440496 100644
--- a/lib/app/utils.js
+++ b/lib/app/utils.js
@@ -65,6 +65,48 @@ export function getMatchedComponentsInstances(route) {
   }))
 }
 
+function getRouteRecordWithParamNames (route) {
+  return route.matched.map(m => {
+    var paramNames = m.path.match(new RegExp(':[^\\/\\?]+', 'g'))
+    if (paramNames !== null) {
+      paramNames = paramNames.map(function (name) {
+        return name.substring(1)
+      })
+    }
+    return {
+      routeRecord: m,
+      paramNames: paramNames
+    }
+  })
+}
+
+export function getChangedComponentsInstances (to, from) {
+  var records = getRouteRecordWithParamNames(to)
+  var r = []
+  var parentChange = false
+  for (var i = 0; i < records.length; i++ ) {
+    var paramNames = records[i].paramNames
+    var instances = records[i].routeRecord.instances
+    instances = Object.keys(instances).map(function (key) {
+      return instances[key]
+    })
+    if (parentChange) {
+      r = [].concat(r, instances)
+    } else if (paramNames !== null) {
+      for (var pi in paramNames) {
+        var name = paramNames[pi]
+        if (to.params[name] !== from.params[name]) {
+          parentChange = true
+          r = [].concat(r, instances)
+          break
+        }
+      }
+    }
+  }
+  return r
+}
+
+
 export function flatMapComponents(route, fn) {
   return Array.prototype.concat.apply([], route.matched.map(function (m, index) {
     return Object.keys(m.components).map(function (key) {