如何从具有phonegap数据库SQLite查询的内部函数返回值到外部函数

Question

This is my code

hasSubAcc = function(accPid) {
    $.mobile.eazydb.transaction(function(tx) {
        tx.executeSql('SELECT * FROM Account WHERE Account_Parent_ID="'+accPid+'"', [],
            function(tx, rs){
                if(rs.rows.length == 0) {
                    return false;
                } else {
                    return true;
                }
        });
    });
}

and the method accessed by

alert(hasSubAcc(accid));

this alert prints undefined. whats wrong with this code. Any solutions plz.Thanks.

Answer 1

The problem is very clear, as you are using heavy process(ie database) inside a function so jquery runs this function in seperate thread parallel to your main thread now in this condition your value will always get undefined.

you can make a global variable var hasSubAcc=-1; now after checking condition

if(rs.rows.length == 0) {
                    hasSubAcc=0;
                } else {
                    hasSubAcc=1;
                }

now give a small delay using

setTimeout(function(){
alert(hasSubAcc);

},500);

or

while(hasSubAcc==-1){
//do nothing
}
alert(hasSubAcc);