如何使用Javascript和HTML5数据库替换表中的现有联系人

Question

I am trying to add a contact in a table. The logic is simple , if the contact already exist confirm modal will ask for confirmation for replacement. Otherwise the contact will be inserted as a new contact.

The addContact() method is called from a html page with onClick event . The problem is newContact() is called but it's not doing anything , what is the problem ?

 function addContact() {
        var conName = document.getElementById("conName").value;
        var conNumber = document.getElementById("conNumber").value;       
        newContact(conName, conNumber);
    }

    function newContact(conName, conNumber) {
        var db = window.openDatabase("myDB", "1.0", "myDB", 200000);
        db.transaction(function(tx) {
        tx.executeSql("SELECT * FROM contact", [], function(tx, rs) {
                var contactAlreadyExist=false;
                for (var i = 0; i < rs.rows.length; i++) {
                    var row = rs.rows.item(i);
                    if(row['name']==conName){
                        if (confirm("Want to replace contact " + conName + "?")) {
                            var db = window.openDatabase("qpdio", "1.0", "QPDIO", 200000);
                            db.transaction(function(tx) {
                                var sql = "Update contact set number="+conNumber+" WHERE ID="+row['id'];
                                tx.executeSql(sql);
                                contactAlreadyExist=true;
                                return true;
                            });

                        }
                    }
                }

            });             
            if(!contactAlreadyExist){
                tx.executeSql("INSERT INTO contact (name, number) VALUES ('" + conName + "','" + conNumber + "')");
                console.log("Here");
            }
        },errorAddingContact, successAddingContact);

    }

    function errorAddingContact(err) {
        navigator.notification.alert("Error Adding Contact " + err.code, null,
                "Error", "Ok");
    }

    function successAddingContact() {
        navigator.notification.alert("Contact Saved successfully!", null,
                "Information", "Ok");       
    }

Answer 1

Can you try this? And let me know if there are errors? I'll edit this answer accordingly. Also if you can check the code alignment (tabs/spaces especially for lines with brackets), it would be good as I think it's a bit messy, maybe due to copy-paste

Note that

• I am not a phonegap expert
• The error and success call back now have alerts
• executeSql now has 4 parameters (including error callback), yours seemed to have 5, but this might be because of the code alignment makes me misread the brackets
• confirm doesn't need if, does it? Please check the API
• note that the location of contactAlreadyExist check is now still within the successCallback of executeSQL

Code

function newContact(conName, conNumber) {
    var db = window.openDatabase("myDB", "1.0", "myDB", 200000);
    db.transaction(
        function(tx) {
            tx.executeSql
            (
                 "SELECT * FROM contact", 
                 [], 
                 function(tx, rs) {
                     var contactAlreadyExist=false;
                     for (var i = 0; i < rs.rows.length; i++) 
                     {
                         var row = rs.rows.item(i);
                         if(row['name']==conName)
                         {
                            confirm
                            (
                                "Want to replace contact " + conName + "?", 
                                function() 
                                {
                                    var db = window.openDatabase("qpdio", "1.0", "QPDIO", 200000);
                                    db.transaction(function(tx) {
                                        var sql = "Update contact set number="+conNumber+" WHERE ID="+row['id'];
                                        tx.executeSql(sql);
                                        contactAlreadyExist=true;
                                        return true;
                                    });
                                }
                            );
                         }
                     }
                     if (!contactAlreadyExist) 
                     {
                        tx.executeSql("INSERT INTO contact (name, number) VALUES ('" + conName + "','" + conNumber + "')");
                        console.log("Here");   
                     }
                },
                errorAddingContact
           );  
        }
    ,errorAddingContact, successAddingContact);                               
}

function errorAddingContact(err) {
    alert(err.code);
    navigator.notification.alert("Error Adding Contact " + err.code, null,
            "Error", "Ok");
}

function successAddingContact() {
    alert(err.code);
    navigator.notification.alert("Contact Saved successfully!", null,
            "Information", "Ok");       
}