Wednesday, January 16, 2013

Entity Framework For Html5 SQLite, PhoneGap Data Access Framework

Notice: The HTML5 SQLite library has been picked out from Nova PhoneGap Framework, so it is a standalone library now. The latest source code and documentation have been moved to github https://github.com/leotsai/html5sqlite
Nova PhoneGap Framework has developed a framework for data access in html5 SQLite. It works in a similar way with the C# EntityFramework (EF). See documentation
Take a look at the below code then you will know it's so easy to define your database and entities, and query, add, update, delete entities from the db.
// define dbContext & entities------------------------------------
var DemoDataContext = function () {
    nova.data.DbContext.call(this, "Demo", "1.0", "Demo DB", 1000000);

    this.users = new nova.data.Repository(this, User, "users");
    this.roles = new nova.data.Repository(this, Role, "roles");
};

DemoDataContext.prototype = new nova.data.DbContext();
DemoDataContext.constructor = DemoDataContext;

var User = function () {
    nova.data.Entity.call(this);
    this.name = "";
    this.password = "";
    this.birthYear = 1980;
    this.createdDate = new Date();
    this.deleted = false;
};
User.prototype = new nova.data.Entity();
User.constructor = User;

var Role = function () {
    nova.data.Entity.call(this);
    this.name = "";
    this.createdDate = new Date();

};
Role.prototype = new nova.data.Entity();
Role.constructor = Role;
// end define dbContext & entities------------------------------------

// service methods----------------------------------------------------
function getAllUsers(callback) {
    new DemoDataContext().users.toArray(function (users) {
        alert(users.length);
        callback(users);
    });
}

function getUserByName(name, callback) {
    new DemoDataContext().users.where("name='" + name + "'").toArray(function (users) {
        callback(users.firstOrDefault());
    });
}

function addRole(roleName, callback) {
    var role = new Role();
    role.name = roleName;
    var db = new DemoDataContext();
    db.roles.add(role);
    db.saveChanges(callback);
}

function updateUserPassword(username, password, callback) {
    getUserByName(username, function (user) {
        if (user == null) {
            throw "no user found.";
        }
        user.password = password;
        var db = new DemoDataContext();
        db.users.update(user);
        db.saveChanges(callback);
    });
}

function deleteUserByName(name, callback) {
    getUserByName(name, function (user) {
        if (user == null) {
            throw "no user found.";
        }
        var db = new DemoDataContext();
        db.users.remove(user);
        db.saveChanges(callback);
    });
}

// end service methods----------------------------------------------------

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