Question

我正在使用YDN DB for IndexedDB，我想使用其id从对象存储中删除记录。这是我的架构：

var personsSchema = {
name: "persons",
keyPath: "id",
autoIncrement: true,
indexes: [{
    name: "id",
    unique: true
}, {
    name: "firstname",
    unique: false,
    multiEntry: false
}, {
    name: "lastname",
    unique: false,
    multiEntry: false
}]
};

schema = {
    stores: [personsSchema]
};

var db = new ydn.db.Storage("xdb", schema);

现在，我有删除记录的功能：

    function deleteEntry(id){
        var id = parseInt(id);
        var objectStore = "persons";
        var iterator = new ydn.db.ValueCursors(objectStore, "id", ydn.db.KeyRange.only(id));
        var mode = "readwrite";
        request = db.open(iterator, 1).then(function(cursor){
            cursor.clear();
        }, mode);
    }

这个函数给了我这个错误：

Uncaught ydn.error.ArgumentException: Second argument must be cursor range iterator.

感谢您的回复。

Answer 1

应该是：

function deleteEntry(id){
    var id = parseInt(id);
    var objectStore = "persons";
    var iterator = new ydn.db.IndexValueCursors(objectStore, "id", ydn.db.KeyRange.only(id));
    var mode = "readwrite";
    request = db.open(function(cursor){
        cursor.clear();
    }, iterator, mode).then(function() {
        console.log('cleared')
    });
}

但由于id是主键，因此您无需编入索引，它应该只是：

function deleteEntry(id){
    var id = parseInt(id, 10);
    var keys = db.remove("persons", id);
}

如果id不是主键，则以下代码运行效率更高，因为它不会不必要地检索记录值。

function deleteEntry(id){
    var id = parseInt(id);
    var objectStore = "persons";
    db.keys(objectStore, "id", ydn.db.KeyRange.only(id)).done(function(keys) { 
      db.remove(objectStore, keys);
    };
}

我更正了api doc example。

YDN DB按ID删除记录（IndexedDB）

1 个答案: