为什么storage.set / storage.get无法在Chrome中设置/获取数据？

时间：2016-08-28 10:51:19

标签： google-chrome-extension firefox-webextensions

我开始学习在Chrome中调试扩展程序。我在Chrome中遇到此问题但在Firefox中我们没有问题。问题是在Chrome中我无法获取已保存到存储空间的数据。

我在后台脚本中有这个功能。我将断点添加到storage.set的行。我重新启动了addon，我可以访问MyNamespace.data中的所有数据...插件会打印安装成功的通知，但是当我尝试获取数据时，日志会显示空对象。

MyNamespace.checkIfExists = function (item) {
  if (chrome.runtime.lastError) {
    MyNamespace.notify("check-fail");
    console.log("error:" + chrome.runtime.lastError);
    console.log(chrome.runtime.lastError);
  } else {
    if ( ! ( "initiated" in item ) )
      {
      console.log("I'm initiating .. item:");
      console.log(item);
      /* Insert new data object */
      /* This saves default values into storage */       
      chrome.storage.local.set({
        easy:     MyNamespace.data.easy,
        advanced: MyNamespace.data.advanced,
        images:   MyNamespace.data.images,
        inspector:MyNamespace.data.inspector,
        extractor:MyNamespace.data.extractor,
        profiles: MyNamespace.data.profiles,
        default_profiles: MyNamespace.data.default_profiles        
        }, 
        () => {
          if (chrome.runtime.lastError) 
            { 
            MyNamespace.notify("write-fail");            
            console.log("local.set Error: " + chrome.runtime.lastError); }
          else
            {                         
            MyNamespace.notify("write-succeess");
            chrome.storage.local.get( {initiated: undefined, easy:undefined}, 
              (result) => {
                if (typeof result === undefined )
                  MyNamespace.notify("write-fail");
                console.log("found:");
                console.log(result);
                console.log("/end");
                }
              )
            chrome.storage.local.set( {initiated:true} );            
            MyNamespace.initiated = true;
            }
        } );
      }
    else
      MyNamespace.initiated = true;
  }
};

控制台中的结果：

I'm initiating .. item:
namespace.js:125 Object {}
namespace.js:149 found:
namespace.js:150 Object {}
namespace.js:151 /end

控制台没有错误。在Chrome中，对象为空。在Firefox中，我看到一个要保存的对象，一个属性未定义。

的manifest.json 

{
  "applications": {
  "gecko": {
    "id": "some-options@mozilla.org",
    "strict_min_version": "48.0a1"
    }
  },
"description": "An example options ui",
"homepage_url": "https://github.com/mdn/webextensions-examples/tree/master/favourite-colour",
"manifest_version": 2,
"name": "Favourite colour",
"version": "1.0",
"icons": {  
  "48": "icons/eye-icon-colored-48.png"    
},
"options_ui": {
  "page": "options.html",
  "open_in_tab": true
  },
"browser_action": {
  "default_title": "Adapt page",
  "browser_style": true,
  "default_popup": "popup/settings.html",
  "default_icon": {
    "48": "icons/eye-icon-48.png"
  }
},
"web_accessible_resources": [
  "icons/hotkeys-icon-32.png"
  ],
"permissions": ["storage", "tabs", "activeTab", "notifications"],
"background": {
  "page": "background_scripts/background_scripts_bug_fix.html"
 },
"content_scripts": [
    {
    "matches": ["<all_urls>" ],
    "run_at": "document_start",
    "js": [
      "content_scripts/jquery-3.0.0.js",
      "content_scripts/namespace.js",
      "content_scripts/easy.js",
      "content_scripts/addListeners.js"
      ]
    }
  ],
"commands": {
  "easy": {
    "suggested_key": {
      "default": "Ctrl+Shift+U"    
    },
    "description": ""
  }
 }
}

我已添加此侦听器，以便在保存存储数据时触发：

chrome.storage.onChanged.addListener(function(changes, namespace) {
  for (key in changes) {
    var storageChange = changes[key];
    console.log('Storage key "%s" in namespace "%s" changed. ' +
                'Old value was "%s", new value is "%s".',
                key,
                namespace,
                storageChange.oldValue,
                storageChange.newValue);
  }
});

我得到了这个日志：

    namespace.js:241 Storage key "default_profiles" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:241 Storage key "easy" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:241 Storage key "extractor" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:241 Storage key "images" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:241 Storage key "initiated" in namespace "local" changed. Old value was "true", new value is "undefined".
    namespace.js:241 Storage key "inspector" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:241 Storage key "profiles" in namespace "local" changed. Old value was "Object", new value is "undefined".
    namespace.js:124 I'm initiating .. item:
    namespace.js:125 Object {}
    namespace.js:241 Storage key "advanced" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "default_profiles" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "easy" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "extractor" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "images" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "inspector" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:241 Storage key "profiles" in namespace "local" changed. Old value was "undefined", new value is "Object".
    namespace.js:152 found:
    namespace.js:153 Object {}
namespace.js:154 /end
namespace.js:241 Storage key "initiated" in namespace "local" changed. Old value was "undefined", new value is "true".

那是什么意思？我在Chrome中看到了单词Object（），白色字母（黑暗主题），但它不像我可以点击并查看对象的链接。这表明数据已加载。但为什么我不能在对象中观察数据？

  1. 我无法进入回调，因此无法观看数据
  2. 我无法看到控制台中的对象{}中的内容....它看起来像是空的但是在监听器中我得到的消息存储已被更改。
  3. 导致storage.get回调结果为空...不包含属性

    4. 我已使用此代码检查了它：     for（结果中的var键）          if（hasOwnProperty.call（result，key））                console.log（＆＃34; key：＆＃34; + key）;

    在Chrome中没有列出任何属性，在Firefox工具箱/控制台中列出了它们。

    据我所知，storage.set回调应该在保存更改完成后触发，并关闭db文件进行写入。所以我希望在storage.set

    中解冻storage.get不存在任何问题

    有人可以澄清这里发生了什么吗？为什么在Firefox中这有效，但在Chrome中没有？如何解决问题？

1 个答案:

答案 0 :(得分：2)

  

chrome.storage.local.get（{initiated：undefined，easy：undefined}，

将不会得到任何结果，因为只使用参数对象的中间字符串化检索定义的键（1，2）：self = this;生成class MessageList extends React.Component { constructor(props){ super(props); this.state = { messages: [] }; componentDidMount() { var self = this; var firebaseRef = firebase.database().ref(); firebaseRef.once('value') .then(function(dataSnapshot) { self.setState({ messages: messages }); }); } } render() { ... } } - 它＆＃39; s空。

当您不提供默认值时，请使用一组键名：

JSON.stringify({a:undefined,b:undefined})

P.S。使用console.log format string中的'{}'或chrome.storage.local.get( ['initiated', 'easy'], 来显示对象的实际内容。

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