/// <summary>
/// Adds a new Book to database context and to local memory collection.
/// Raises <event>OnDatabaseError</event> when exception is thrown from changing the database context.
/// </summary>
/// <param name="book">Book object to be added</param>
/// <returns>Returns true if operation is successful, false otherwise</returns>
public bool AddBook(Book book)
{
if (!IsLibrarian)
{
return(false); //if not a librarian return false
}
try
{
//add book to database context
context.Books.Add(book);
context.SaveChanges();
}
catch (Exception ex)
{
//send OnDatabaseError event
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
return(false);
}
bookInventory.Add(book);
return(true);
}
/// <summary>
/// Checks in a book. Makes appropriate changes to the database and local memory collections
/// </summary>
/// <param name="log">CheckOut log to be used for the check in operations</param>
/// <returns></returns>
public bool CheckIn(CheckOutLog log)
{
if (!IsLibrarian) //if not a librarian
{
return(false);
}
try
{
//remove log from context and save changes
context.CheckOutLogs.Remove(log);
context.SaveChanges();
}
catch (Exception ex)
{
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
return(false);
}
//remove log from memory collection
checkoutLogs.Remove(log);
return(true);
}
//Returns the newly created Author object when opration is successful, returns null otherwise.
/// <summary>
/// Creates a new Author and MAuthor object with the properties set to the arguments passed.
/// Author and MAuthor are added to the database context and local collection respectively.
/// Raises <event>OnDatabaseError</event> when exception is caught from attempting to change database context.
/// </summary>
/// <param name="firstName">First name of author</param>
/// <param name="lastName">Last name of author</param>
/// <param name="bio">Bio of author</param>
/// <returns>Returns true if operation is successful, false otherwise</returns>
public Author CreateAuthor(string firstName, string lastName, string bio)
{
try
{
//create person
Person addPerson = new Person();
addPerson.FirstName = firstName;
addPerson.LastName = lastName;
//add to database to get personID
context.People.Add(addPerson);
context.SaveChanges();
}
catch (Exception ex)
{
//Rase OnDatabaseError event
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
return(null);
}
try
{
//retrieve Person from database with assigned ID
Author result = new Author();
Person addPerson = (from p in context.People
where p.FirstName == firstName && p.LastName == lastName
select p).First();
result.Person = addPerson;
result.PersonId = addPerson.PersonId;
result.Bio = bio;
//Add author to people list
MAuthor ma = new MAuthor(result);
peopleList.Add(ma);
//Add author to database
context.Authors.Add(result);
context.SaveChanges();
return(result);
}
catch (Exception ex)
{
//Raise OnDatabaseError event
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
return(null);
}
}
/// <summary>
/// Check Out Book, make changes to the database and local collections
/// </summary>
/// <param name="book">Book to be checked out</param>
/// <param name="cardHolder">MCardholder that is checking out the book</param>
/// <param name="error">an error string to be outputted should a check out error occur</param>
/// <returns></returns>
public bool CheckOut(Book book, MCardholder cardHolder, out string error)
{
if (!IsLibrarian) //if not a librarian
{
error = "You are not authorized to check out a book.";
return(false);
}
if (cardHolder.HasOverdueBooks)
{
error = "User has Overdue books, cannot check out additional books.";
return(false);
}
if (book.CopiesAvailable > 0) //Make sure that there is a copy available
{
//Create a checkout log
CheckOutLog log = new CheckOutLog
{
Book = book,
Book_BookId = book.BookId,
CheckOutDate = DateTime.Now,
Cardholder_PersonId = cardHolder.ID,
Cardholder = cardHolder.Cardholder
};
try
{
//Add log to context and save
context.CheckOutLogs.Add(log);
context.SaveChanges();
}
catch (Exception ex)
{
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
error = "Cannot check out book. Please try again later.";
return(false);
}
//add log to memory collection
checkoutLogs.Add(log);
error = "";
return(true);
}
error = string.Format("{0} could not be checked out, no copies available", book.Title);
return(false);
}
/// <summary>
/// Broadcasts OnDatabaseError events, takes a <c>DatabaseEventArgs</c> as argument.
/// </summary>
/// <param name="e"></param>
private void OnDatabaseErrorRaised(DatabaseEventArgs e)
{
DatabaseErrorHandler handler = OnDatabaseError;
if (handler != null) //make sure that there are subscribers to the event
{
handler(this, e);
}
}
/// <summary>
/// Saves changes to database context.
/// Raises <event>OnDatabaseError</event> when exception occurs
/// </summary>
public void Save()
{
try
{
context.SaveChanges();
}
catch (Exception ex)
{
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
}
}
public event DatabaseErrorHandler OnDatabaseError; //event to broadcast if a database error has occurred
#endregion
/// <summary>
/// Constructor. Opens a connection to the database using Entity Framework
/// and loads all database entities into local collections and classes.
/// </summary>
public LibraryClientController()
{
context = new LibraryDB();
try
{
//If the context collections are null or contains no elements, load from XML using XMLSaverLoader
//if (context.Books == null || context.Books.Count() <= 0 || context.People == null || context.People.Count() == 0)
//{
// XMLSaverLoader xmlSaverLoader = new XMLSaverLoader();
// xmlSaverLoader.LoadFromLocalXML();
// Message = "Database Loaded";
//}
//else
//{
// Message = "Database Already Loaded";
//}
//Add to collections
LoadPeopleList();
LoadToBookInventory();
LoadCheckOutLogList();
//Set isLibrarian
IsLibrarian = false;
}
catch (Exception ex)
{
while (ex.InnerException != null)
{
ex = ex.InnerException;
}
//Message = ex.Message;
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
}
}
/// <summary>
/// Removes Book object in the argument from database context and local memory collection.
/// Raises <event>OnDatabaseError</event> when exception is caught from attempting to change the database context.
/// </summary>
/// <param name="b">Book object to be removed</param>
/// <returns>returns true if operation is successful, false otherwise.</returns>
public bool RemoveBook(Book b)
{
if (!IsLibrarian)
{
return(false); //return false if IsLibrarian is false.
}
if (b.IsCheckedOut) //check if books are checked out or not
{
OnDatabaseErrorRaised(new DatabaseEventArgs("Cannot remove book, all copies must be checked in"));
return(false);
}
else //books are all checked in
{
try
{
//remove from database
context.Books.Remove(b);
context.SaveChanges();
}
catch (Exception ex)
{
while (ex != null)
{
ex = ex.InnerException;
}
DatabaseEventArgs e = new DatabaseEventArgs(ex.Message);
OnDatabaseErrorRaised(e);
return(false);
}
//remove from memory
bookInventory.Remove(b);
return(true);
}
}
/// <summary>
/// Event handler for OnDatabaseError event
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnDatabaseErrorHandler(object sender, DatabaseEventArgs e)
{
MessageBox.Show(e.Error, "Database Error", MessageBoxButton.OK, MessageBoxImage.Error);
}
/// <summary>
/// Event handler for OnDatabaseError events
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnDatabaseErrorHandler(object sender, DatabaseEventArgs e)
{
MessageBox.Show(e.Error);
}
