HTML5 WebSQL：如何知道db事务何时完成？ [英] HTML5 WebSQL: how to know when a db transaction finishes?

问题描述

我有以下代码获取一个json记录集，并在客户端Web Sql存储上的三个不同的表中插入一些数据。

I've the following code that gets a json recordset and insert some data in three different tables on the client Web Sql storage.

如何截取的databaseSync（）函数？
我想做的是显示一个警报或更好的ajax微调框gif为了通知用户同步完成时。

How can I intercept the end of databaseSync() function? What I want to do is display an alert or better an ajax spinner gif in order to inform the user when the sync is complete.

非常感谢您的help，
ciao！

Many thanks for your help, ciao!

function databaseSync() {

        // table one
        $.getJSON("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=one", function(json) {
            $.each(json.results, function(i, res) {
                db.transaction(function(tx) {
                    tx.executeSql("INSERT INTO table1 (A, B, C, D) VALUES (?,?,?,?) ", [res.A, res.B, res.C, res.D], onSuccess, onError);
                });
            });
        });

        // table two
        $.getJSON("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=two", function(json) {
            $.each(json.results, function(i, res) {
                db.transaction(function(tx) {
                    tx.executeSql("INSERT INTO table1 (A, B, C, D) VALUES (?,?,?,?) ", [res.A, res.B, res.C, res.D], onSuccess, onError);
                });
            });
        });

        // table three
        $.getJSON("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=three", function(json) {
            $.each(json.results, function(i, res) {
                db.transaction(function(tx) {
                    tx.executeSql("INSERT INTO table1 (A, B, C, D) VALUES (?,?,?,?) ", [res.A, res.B, res.C, res.D], onSuccess, onError);
                });
            });
        });


    }

推荐答案

Ok，这是我的第五次修订，但我喜欢这个问题，我不断提出更好的想法。这一个使用 jquery延迟对象，我认为它最终涵盖所有情况，并工作方法它应该。

Ok, this is my fifth revision, but I liked this question and I keep coming up with better ideas. This one uses jquery deferred objects and I think it finally covers all cases and works the way it should.

function tableInsert(url) {
    var dfd = $.Deferred();
    var arr = [];
    $.getJSON(url, function(json) {
        $.each(json.results, function(i, res) {
            var dfd = $.Deferred();
            arr.push(dfd.promise()); 
            db.transaction(function(tx) {
                tx.executeSql(
                    "INSERT INTO table1 (A, B, C, D) VALUES (?,?,?,?) ", 
                    [res.A, res.B, res.C, res.D], 
                    function(){
                        onSuccess(dfd.resolve);
                    }, 
                    function(){
                        onError(dfd.resolve);
                    }
                );
            });
        });
        $.when.apply(this, arr).then(dfd.resolve);
    });
    return dfd.promise();
}

function databaseSync() {

    $.when( tableInsert("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=one"),
            tableInsert("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=two"), 
            tableInsert("http://192.168.1.40:8888/iOS/mobilesrv/index.php?ACT=three"))
        .then(function(){
            console.log( 'All processing complete' );
        });
}

为了这个工作，你需要改变onSuccess和onError来执行解决函数作为一个回调函数做任何其他的事情后，他们做，然后这应该为你工作。我希望你觉得这很有用。

For this to work you'll need to change onSuccess and onError to execute the resolve function as a callback function after doing whatever else it is they do and then this should work for you. I hope you find this useful.

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