/// <summary>
/// Gets the existing connection if any for DB
/// Used for updating an existing medicine
/// </summary>
/// <param name="medicineId">Medicine to be retrieved from DB</param>
public MedicineViewModel(int medicineId)
{
db = App.ViewModel.db;
db.Refresh(RefreshMode.OverwriteCurrentValues, db.Medicines); // Clear any unsaved changes
Medicine = db.Medicines.SingleOrDefault(m => m.Id == medicineId);
}
/// <summary>
/// Create a new medicine with current instance
/// Sets the created_at and updated_at columns also
/// </summary>
internal void Create()
{
db = App.ViewModel.db;
db.Medicines.InsertOnSubmit(this.medicine);
db.SubmitChanges();
}
public GroupViewModel(string groupName)
{
db = App.ViewModel.db;
Group = db.Groups.Single(g => g.Name == groupName);
}
/// <summary>
/// Gets the existing connection if any for DB
/// Creates an empty Medicine instance
/// Used for creating a new medicine as we do not have any ID for it yet
/// </summary>
public MedicineViewModel()
{
db = App.ViewModel.db;
db.Refresh(RefreshMode.OverwriteCurrentValues, db.Medicines); // Clear any unsaved changes
Medicine = new Medicine();
}
/// <summary>
/// Shows the error message that the group name already exists
/// Disposes the Connection and creates a new connection as there is no way to clear changes but not submitted
/// </summary>
private void HandleDuplicateGroup()
{
MessageBox.Show(String.Format("Group \"{0}\" already exists.\r\nUse the existing one or choose a different name", this.group.Name), "OOPS!", MessageBoxButton.OK);
db.Dispose();
db = App.ViewModel.GetNewConnection();
}
/// <summary>
/// Sets the DB Context
/// Loads all groups if asked for
/// </summary>
/// <param name="loadAllGroups">Flag to indicate whether to load groups</param>
public GroupViewModel()
{
db = App.ViewModel.db;
Group = new Group();
LoadAllGroups();
}
public MainViewModel()
{
db = new MedicineContext(App.DbConnection);
}
/// <summary>
/// Instantiates new DB connection. Used when we dispose the old connection
/// </summary>
/// <returns>New connection to DB</returns>
public MedicineContext GetNewConnection()
{
db = new MedicineContext(App.DbConnection);
return db;
}
/// <summary>
/// :: Important ::
/// Aim: Update DB to latest version using currentDBVersion variable.
///
/// Working:
/// Just like migrations in Rails.
/// Each case in the switch has changes in that specific DB version
/// default case implies latest version and so no changes
/// At the end of each case we add goto to next case to fall through until we reach the latest version
///
/// Notes:
/// Target version will always be 'one' version higher than the current one. Increments in DB versions is always by 1
/// All the changes to schema from the targetVersion will be run
/// </summary>
private void UpdateDB()
{
using (var db = new MedicineContext(App.DbConnection))
{
var adapter = db.CreateDatabaseSchemaUpdater();
switch (GetNextDBVersion(adapter.DatabaseSchemaVersion))
{
case 0:
// Version 0. Initial DB
goto case 1;
case 1:
// Version 1 changes
// New Columns
adapter.AddColumn<Medicine>("IsUsing");
adapter.AddColumn<Medicine>("Quantity");
adapter.AddColumn<Medicine>("QuantityType");
adapter.AddColumn<Medicine>("ReminderIds");
adapter.AddColumn<Medicine>("DosageType");
// New Tables
adapter.AddTable<Group>();
adapter.AddTable<Medicine_Group>();
goto default;
default:
// DB upto date
break;
}
adapter.DatabaseSchemaVersion = currentDBVersion;
adapter.Execute();
}
}
/// <summary>
/// Inserts sample data into the database
/// </summary>
/// <param name="db">Database context to use</param>
private void InsertSampleData(MedicineContext db)
{
// Sample Medicines
Medicine m1 = new Medicine()
{
Name = "saridon (sample)",
MfgDate = DateTime.Now,
ExpDate = DateTime.Now.AddMonths(3),
CureFor = "Headache",
Dosage = "4",
DosageType = "cups",
AgeGroup = "18+",
Price = 20.50F,
BoughtAddress = "Near Canara bank, Kormangala, Bangalore. Ph: 080-23399239",
Quantity = 2,
QuantityType = "pills",
CreatedAt = DateTime.Now,
UpdatedAt = DateTime.Now
};
db.Medicines.InsertOnSubmit(m1);
Medicine m2 = new Medicine()
{
Name = "nice (sample)",
MfgDate = DateTime.Now,
ExpDate = DateTime.Now.AddMonths(3),
IsUsing = true,
CureFor = "Fever",
Dosage = "3",
DosageType = "spoons",
AgeGroup = "20+",
Price = 25.50F,
BoughtAddress = "Indiranagar, Bangalore. Ph: 080-23399239",
Quantity = 4,
QuantityType = "pills",
CreatedAt = DateTime.Now,
UpdatedAt = DateTime.Now
};
db.Medicines.InsertOnSubmit(m2);
db.SubmitChanges();
// Sample Groups
Group g1 = new Group()
{
Name = "Is Using (sample)",
CreatedAt = DateTime.Now,
UpdatedAt = DateTime.Now
};
db.Groups.InsertOnSubmit(g1);
Group g2 = new Group()
{
Name = "Not Using (sample)",
CreatedAt = DateTime.Now,
UpdatedAt = DateTime.Now
};
db.Groups.InsertOnSubmit(g2);
db.SubmitChanges();
// Sample Associations
db.MedicinesGroups.InsertOnSubmit(new Medicine_Group()
{
Medicine = m1,
Group = g1
});
db.MedicinesGroups.InsertOnSubmit(new Medicine_Group()
{
Medicine = m2,
Group = g2
});
db.SubmitChanges();
}
/// <summary>
/// Creates the Medicines Catalogue DB if it doesn't exist
/// Adds a sample medicine
/// </summary>
private void CreateDB()
{
using (var db = new MedicineContext(DbConnection))
{
if (!db.DatabaseExists())
{
db.CreateDatabase();
InsertSampleData(db);
db.SubmitChanges();
var adapter = db.CreateDatabaseSchemaUpdater();
adapter.DatabaseSchemaVersion = currentDBVersion;
adapter.Execute();
}
}
}
