MobileFirst Platform JSONStore 从数据库读取时出错

Question

IBM MobileFirst 版本：6.3 手机 OS：Android 4.4.4

我有一个用例，我们需要将单个或多个 base64 编码的图像字符串存储在集合内的单个文档中。（由于用例的性质，无法将图像拆分为集合中的多个文档）

将最多 7 个 base64 编码的图像字符串存储到同一个文档中可以正常工作。（包含 7 个 base64 字符串图像的文档已添加到 JSONStore）。将包含 8 个 base64 编码字符串图像的文档添加到集合中的同一文档时。文档已成功添加到集合中。但是当在集合上调用 findAll() 时（它只包含 1 个文档和 8 个 base64 编码的图像；在这个用例中，需要一个 findAll() 因为填充搜索字段的数据在数据时不存在从集合中获取）；发生以下错误：

Java:

E/JSONSTORE(24451): JSONStoreLogger.logError in JSONStoreLogger.java:189 :: Error when attempting to find a document. An error occurred when reading from the database.
E/JSONSTORE(24451): com.worklight.jsonstore.exceptions.JSONStoreFindException: Error when attempting to find a document. An error occurred when reading from the database.
E/JSONSTORE(24451):     at com.worklight.jsonstore.api.JSONStoreCollection.findDocuments(JSONStoreCollection.java:896)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.FindActionDispatcher.databaseActionDispatch(FindActionDispatcher.java:117)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.BaseDatabaseActionDispatcher.actionDispatch(BaseDatabaseActionDispatcher.java:36)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.BaseActionDispatcher.dispatch(BaseActionDispatcher.java:90)
E/JSONSTORE(24451):     at com.worklight.androidgap.plugin.DispatchingPlugin$ActionDispatcherRunnable.run(DispatchingPlugin.java:79)
E/JSONSTORE(24451):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
E/JSONSTORE(24451):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
E/JSONSTORE(24451):     at java.lang.Thread.run(Thread.java:841)
E/JSONSTORE(24451): Caused by: java.lang.IllegalStateException: get field slot from row 0 col 0 failed
E/JSONSTORE(24451):     at net.sqlcipher.CursorWindow.getLong_native(Native Method)
E/JSONSTORE(24451):     at net.sqlcipher.CursorWindow.getLong(CursorWindow.java:381)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:110)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractCursor.moveToPosition(AbstractCursor.java:195)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractCursor.moveToNext(AbstractCursor.java:257)
E/JSONSTORE(24451):     at android.database.CursorWrapper.moveToNext(CursorWrapper.java:166)
E/JSONSTORE(24451):     at com.worklight.jsonstore.api.JSONStoreCollection.findDocuments(JSONStoreCollection.java:877)
E/JSONSTORE(24451):     ... 7 more
E/JSONSTORE(24451): JSONStoreLogger.logError in JSONStoreLogger.java:189 :: error while executing find query on database "tempCollection"com.worklight.jsonstore.exceptions.JSONStoreFindException: Error when attempting to find a document. An error occurred when reading from the database.
E/JSONSTORE(24451): com.worklight.jsonstore.exceptions.JSONStoreFindException: Error when attempting to find a document. An error occurred when reading from the database.
E/JSONSTORE(24451):     at com.worklight.jsonstore.api.JSONStoreCollection.findDocuments(JSONStoreCollection.java:896)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.FindActionDispatcher.databaseActionDispatch(FindActionDispatcher.java:117)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.BaseDatabaseActionDispatcher.actionDispatch(BaseDatabaseActionDispatcher.java:36)
E/JSONSTORE(24451):     at com.worklight.androidgap.jsonstore.dispatchers.BaseActionDispatcher.dispatch(BaseActionDispatcher.java:90)
E/JSONSTORE(24451):     at com.worklight.androidgap.plugin.DispatchingPlugin$ActionDispatcherRunnable.run(DispatchingPlugin.java:79)
E/JSONSTORE(24451):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
E/JSONSTORE(24451):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
E/JSONSTORE(24451):     at java.lang.Thread.run(Thread.java:841)
E/JSONSTORE(24451): Caused by: java.lang.IllegalStateException: get field slot from row 0 col 0 failed
E/JSONSTORE(24451):     at net.sqlcipher.CursorWindow.getLong_native(Native Method)
E/JSONSTORE(24451):     at net.sqlcipher.CursorWindow.getLong(CursorWindow.java:381)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:110)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractCursor.moveToPosition(AbstractCursor.java:195)
E/JSONSTORE(24451):     at net.sqlcipher.AbstractCursor.moveToNext(AbstractCursor.java:257)
E/JSONSTORE(24451):     at android.database.CursorWrapper.moveToNext(CursorWrapper.java:166)
E/JSONSTORE(24451):     at com.worklight.jsonstore.api.JSONStoreCollection.findDocuments(JSONStoreCollection.java:877)
E/JSONSTORE(24451):     ... 7 more
E/wl.jsonstore(24451): {"src":"find","err":22,"msg":"INVALID_SEARCH_FIELD","col":"tempCollection","usr":"testUser","doc":{},"res":{}}

Java脚本：

{"src":"findAll","err":22,"msg":"INVALID_SEARCH_FIELD","col":"tempCollection","usr":"testUser","doc":{},"res":{}}

是我做错了什么，还是我使用不当？

编辑：

初始化：

var storeDetails = {
    collections: {
        tempCollection: {}
    },
    options: {
        username: 'ausername',
        password: 'apassword',
        localKeyGen: true //Optional local key generation flag, default false.
    }
};

WL.JSONStore.init(storeDetails.collections, storeDetails.options);

查找全部：

var options = {
    limit: 1
};
WL.JSONStore.get('tempCollection').findAll(options);

Base64 编码的图像字符串：我正在使用 Cordova 相机 API（包含在 Worklight/MF 中）。代码片段：通过使用 Camera.DestinationType.DATA_URL，图像以 base64 编码的字符串形式返回。

var options = {
    quality: 100,
    destinationType: Camera.DestinationType.DATA_URL,
    sourceType: Camera.PictureSourceType.CAMERA,
    allowEdit: true,
    encodingType: Camera.EncodingType.PNG,
    targetWidth: 500,
    targetHeight: 500,
    popoverOptions: CameraPopoverOptions,
    saveToPhotoAlbum: true,
    cameraDirection: Camera.Direction.BACK
};

navigator.camera.getPicture(function (imageData) {
    var doc = {
        src: imageData;
    };
    WL.JSONStore.get('tempCollection').add(doc);
}, function (err) {

}, options);

Answer 1

我能够重现您的问题。在 JSON 文档中添加一些图像作为单个数组的一部分后，我遇到了与您提供的相同的错误。而且，在你显示的错误之前，我可以看到另一个

05-04 20:27:38.934: E/CursorWindow(32148): need to grow: mSize = 1048576, size = 1107180, freeSpace() = 1048482, numRows = 1
05-04 20:27:38.934: E/CursorWindow(32148): Attempting to grow window beyond max size (1048576)
05-04 20:27:38.934: E/Cursor(32148): Failed allocating 1107180 bytes for text/blob at 0,1
05-04 20:27:38.935: D/Cursor(32148): finish_program_and_get_row_count row 0
05-04 20:27:39.151: E/CursorWindow(32148): need to grow: mSize = 1048576, size = 1107180, freeSpace() = 1048482, numRows = 1
05-04 20:27:39.151: E/CursorWindow(32148): Attempting to grow window beyond max size (1048576)
05-04 20:27:39.151: E/Cursor(32148): Failed allocating 1107180 bytes for text/blob at 0,1
05-04 20:27:39.152: D/Cursor(32148): finish_program_and_get_row_count row 0
05-04 20:27:39.152: E/CursorWindow(32148): Bad request for field slot 0,0. numRows = 0, numColumns = 2

所以我的猜测是您强调了设备内存的限制。

当您将多张图片添加到单个 JSON 文档时，您正在创建一个巨大的 JSON 文档。然后当你搜索它时，可能有一些类型的解析操作，或者类似的东西，需要在内存中分配整个 JSON 。 findAll 本身的结果将包含那个巨大的 json 文档。并且可能需要使用连续内存分配。

问题是单个 Android 应用可用的内存总量是有限的。实际值取决于设备制造商。而且它不一定与 "high-end" 设备的性能或设备中可用的总内存有关。一些制造商可能会创建具有 2GB 内存的设备，但每个应用程序只有几 MB 可用，因此他们优先考虑保持许多应用程序运行并行的能力，而不是几个应用程序占用所有资源。

最后，我的建议是您真的应该将每个图像存储在一个独立的 JSON 文档中。您可以拥有一个包含 ID 数组的文档和存储在第二个集合中的图像，或者其他一些替代解决方案。

另请注意，这不是 JSON 商店的限制，而是 Android 平台施加的限制。永远不会允许单个应用程序单独消耗所有内存资源，它总是限制在一些 MB。

MobileFirst Platform JSONStore 从数据库读取时出错

MobileFirst Platform JSONStore An error occurred when reading from the database

android

ibm-mobilefirst

jsonstore