javascript - indexedDB objectStore.get() 总是返回 undefined，尽管在 DB 中有结果

Question

我一直在改造一个旧项目并进行一些改进，但我似乎无法再弄清楚如何从 indexedDB 加载单个条目。我已经清除了数据库并进行了全新导入，我可以在 chrome 检查器资源部分中看到所有记录(包括我用于 entryID 的记录)。我试过提取各种 ID 号，我可以确认所有这些都在检查员的数据库中，它们都返回未定义。这是我正在使用的代码。

/*
    This loads up a specific entry and fills in the #entry-details div with it's data. This div is placed overtop the search 
    content so that when it is closed the user remains exactly where they were and the search does not need to re-process.
*/
function getEntryDetails(){

    var entryID = 193; // just for now, this will be grabbed from somewhere else later

    // Where going to need a varible to store all this generated HTML in
    var html = '';

    // First we need to load up the indexedDB and get the record in question.
    var db = indexedDB.open('pediaCache');

    // lets get a couple of the errors out of the way.
    db.onerror=function(e){html += 'There was an error loading the database.<br/>'+e;}
    db.onblocked=function(e){html += 'Database access blocked.<br/>'+e;}

    // Now for when things go the right way
    db.onsuccess=function(e){
        var db = e.target.result;

        // Get the requested entry
        console.log('Attempting to load entry ID '+entryID);
        var transaction = db.transaction(['entries'],'readonly');
        var objectStore = transaction.objectStore('entries');
        var entry = objectStore.get(entryID);

        entry.onerror = function(e) {
            console.log('error');
            console.log(e.target.result);
            console.log(e);
        };
        entry.onsuccess = function(e) {
            console.log('success');
            console.log(e.target.result);
            console.log(e);
        };

    }

}

这实际上只是对原始版本稍作修改的代码(因为这个功能是相同的，我实际上只修改了这里和导入器中的数据库和 ObjectStore 名称)。在 Chrome 中运行此代码(在我知道所有其他与数据库相关的功能完成后手动触发)甚至会触发“onsuccess”，只是结果未定义(好像该条目不在数据库中，但我再次检查过它在那里)。

根据要求，console.dir(e) 的内容:

{
    "path": {
        "length": 0
    },
    "cancelBubble": false,
    "returnValue": true,
    "srcElement": {
        "readyState": "done",
        "transaction": {
            "onerror": null,
            "oncomplete": null,
            "onabort": null,
            "error": null,
            "db": {
                "onversionchange": null,
                "onerror": null,
                "onclose": null,
                "onabort": null,
                "objectStoreNames": {
                    "0": "entries",
                    "length": 1
                },
                "version": 3,
                "name": "pediaCache"
            },
            "mode": "readonly"
        },
        "source": {
            "autoIncrement": false,
            "transaction": {
                "onerror": null,
                "oncomplete": null,
                "onabort": null,
                "error": null,
                "db": {
                    "onversionchange": null,
                    "onerror": null,
                    "onclose": null,
                    "onabort": null,
                    "objectStoreNames": {
                        "0": "entries",
                        "length": 1
                    },
                    "version": 3,
                    "name": "pediaCache"
                },
                "mode": "readonly"
            },
            "indexNames": {
                "0": "title",
                "length": 1
            },
            "keyPath": null,
            "name": "entries"
        },
        "error": null
    },
    "defaultPrevented": false,
    "timeStamp": 1420434102528,
    "cancelable": false,
    "bubbles": false,
    "eventPhase": 0,
    "currentTarget": null,
    "target": {
        "readyState": "done",
        "transaction": {
            "onerror": null,
            "oncomplete": null,
            "onabort": null,
            "error": null,
            "db": {
                "onversionchange": null,
                "onerror": null,
                "onclose": null,
                "onabort": null,
                "objectStoreNames": {
                    "0": "entries",
                    "length": 1
                },
                "version": 3,
                "name": "pediaCache"
            },
            "mode": "readonly"
        },
        "source": {
            "autoIncrement": false,
            "transaction": {
                "onerror": null,
                "oncomplete": null,
                "onabort": null,
                "error": null,
                "db": {
                    "onversionchange": null,
                    "onerror": null,
                    "onclose": null,
                    "onabort": null,
                    "objectStoreNames": {
                        "0": "entries",
                        "length": 1
                    },
                    "version": 3,
                    "name": "pediaCache"
                },
                "mode": "readonly"
            },
            "indexNames": {
                "0": "title",
                "length": 1
            },
            "keyPath": null,
            "name": "entries"
        },
        "error": null
    },
    "type": "success"
}

以及 objectStore 创建(需要升级)。

    // We need to be able to update the db schema (or create it for that matter)
    db.onupgradeneeded=function(e){
        var db = e.target.result;

        // In the future some of theme might want to get commented out...
        postMessage({'status':'importing','message':'Upgrading local database.'});
        // Check if the table is in there, if it's not then create it
        console.log(db.objectStoreNames);
        if(db.objectStoreNames.contains('entries')==false){
            var db = db.createObjectStore('entries');

            // Create the indexes so we can more easily search and sort and stuff (just one, we sort by name, everything else done by magic)
            db.createIndex('title'  ,'ZTITLE'   ,{unique:false});

        }

    };

Answer 1

找到了问题所在，希望没有人会犯我犯过的同样简单的错误，但万一有人犯了这个问题并遇到了这个问题，这就是问题所在。

我添加到数据库中的键是一个字符串。我要求的 key 是一个整数。

不要像我一样，检查你的数据类型。