iOS Phonegap sqlite database getting locked when app go to background

Question

Now i am developing a phonegap application:

In which the insertion operation in sqlite db getting locked when app go to background in iOS ( The same worked in android ). When the application is in forground the databse operations work smoothly.

Why this happening and how can i handle this ?

might be because iOS does not support multitasking. When the app goes into the background, it is paused; not actually running in the background. While in case of Android there's true multitasking. — Varun Mulloli
My application run in background and collect the location data successfully. But the sqlite operations from background only fails. — Ajmal M A

Manjesh V Manjesh V · Accepted Answer · 2014-07-23T07:02:07

I think you've used for loop for insertion, Javascript in asynchronous in nature.

You need to execute batch sql queries in the following style not with for loop

db = window.openDatabase("Demo", "1.0", "BusinessApp", 200000);

insertIndex = 0;
var insertCounter = 0;
insertBatch = function(array, arrayLength, tableName, fieldQuestions, cb) {
    console.log("Inserting Record :" + insertCounter);
    if (insertIndex < arrayLength) {
        db.transaction(function(tx) {
            var sql = 'INSERT OR IGNORE INTO ' + tableName + ' VALUES ' + fieldQuestions;
            console.log("sql: " + sql);
            console.log("sql:------------- ");
            console.log(array[insertIndex]);

            tx.executeSql(sql, array[insertIndex],
                function(tx, res) {
                    insertIndex++;
                    console.log("Insert success");
                    insertBatch(array, arrayLength, tableName, fieldQuestions, cb);
                }, function() {
                    console.log("Insert failure");
                });
        });

    } else {
        insertIndex = 0;
        cb();
    }
}

db.transaction(populateDB, errorCB, successCB);


function populateDB(tx) {

    tx.executeSql('DROP TABLE IF EXISTS ?', ["news"], function() {
        console.log("success drop")
    }, function() {
        console.log("failure drop")
    });
    tx.executeSql('CREATE TABLE IF NOT EXISTS news (news_id INTEGER,news_header TEXT,news_content TEXT)');

}

function errorCB() {
    alert("Error: Init.js ErrorCB");
}

function successCB() {
    //alert();
    console.log('DB Created Success');
    var dataArray = []
    dataArray.push([1, "ONE", "First News Content"])
    dataArray.push([2, "TWO", "2 News Content"])
    dataArray.push([3, "THREE", "2 News Content"])
    dataArray.push([4, "FOUR", "4 News Content"])

    insertBatch(dataArray, dataArray.length, "news", "(?,?,?)", success)

    function success() {

        console.log("all success")
    }

}

So Every executeSQL function requires previous executeSQL success callback

iOS Phonegap sqlite database getting locked when app go to background

1 Answers