/// <summary>
/// Deletes the <seealso cref="DBObject"/> from the datasource.
/// </summary>
/// <param name="dbObject"><seealso cref="DBObject"/> to delete from the datasource.</param>
///
/// <example>
/// The following example shows how to <see cref="Delete"/> a <seealso cref="Customer"/> with a username of "billy123" from the datasource.
/// <code>
/// List<Customer> customers = DBController.GetAllRecords<Customer>().Where(cust => cust.Username == "billy123").ToList();
/// foreach (Customer customer in customers)
/// DBController.Delete(customer);
/// </code>
/// </example>
///
/// <returns>
/// Whether the delete was successful or not.
/// </returns>
/// <exception cref="OleDbException">
/// Throws an exception when a foreign key linkage is being violated.
/// </exception>
public static bool Delete(DBObject dbObject)
{
using (OleDbConnection dbConnection = new OleDbConnection(CONNECTION_STRING))
{
string table = dbObject.GetType().Name;
string query = $"DELETE FROM {table} WHERE {dbObject.PrimaryKeyPropertyInfo.Name} = {dbObject.PrimaryKey}";
int rowsAffected;
using (OleDbCommand command = new OleDbCommand(query, dbConnection))
{
dbConnection.Open();
try
{
rowsAffected = command.ExecuteNonQuery();
}
catch (OleDbException ex)
{
Console.Error.WriteLine(ex.Message);
throw;
}
}
return(rowsAffected != 0);
}
}
/// <summary>
/// Adds a parameter to the <paramref name="command"/> using the value of the <paramref name="property"/>.
/// </summary>
/// <param name="command">Command to execute against the datasource.</param>
/// <param name="property"><seealso cref="PropertyInfo"/> of which a value will be attained.</param>
/// <param name="dbObject"><seealso cref="DBObject"/> to get the <paramref name="property"/> value from.</param>
private static void AddParameterToCommandFromProperty(OleDbCommand command, PropertyInfo property, DBObject dbObject)
{
object value = property.GetValue(dbObject); // Used to say .GetValue(this)
string name = $"@{property.Name}";
command.Parameters.AddWithValue(name, value);
}
/// <summary>
/// Adds values to the <seealso cref="PropertyInfo"/> placeholders nested in the generated query.
/// </summary>
/// <param name="command">Command to execute against the datasource.</param>
/// <param name="saveType">Specifies how to save the <seealso cref="DBObject"/></param>
/// <param name="dbObject"><seealso cref="DBObject"/> to get information from.</param>
private static void AddValuesToPropertyPlaceholders(OleDbCommand command, SaveTypes saveType, DBObject dbObject)
{
IEnumerable <PropertyInfo> propertyList = dbObject.SchemaFieldProperties;
if (saveType == SaveTypes.Update)
{
propertyList = propertyList.Where(pi => !pi.GetCustomAttribute <SchemaField>().IsPrimaryKey);
}
foreach (PropertyInfo property in propertyList)
{
AddParameterToCommandFromProperty(command, property, dbObject);
}
}
