private static void RetrievingDataGraphs()
{
// Fetch a Topic Record and all related Comments to that Topic
Topic eagerLoadedTopic;
using (var context = new DiscussionBoardContext())
{
// Example of Eager Loading
eagerLoadedTopic = context.Topics.Where(t => t.TopicName
.Contains("Will Mr.Gates ever"))
.Include(t => t.Comments)
.FirstOrDefault();
}
Topic explicitLoadedTopic;
using (var context = new DiscussionBoardContext())
{
// Example of Explicit Loading
explicitLoadedTopic = context.Topics.Where(t => t.TopicName
.Contains("Will Mr.Gates ever"))
.FirstOrDefault();
// Explicit Loading done here
context.Entry(explicitLoadedTopic)
.Collection(t => t.Comments)
.Load();
}
}
private static void DeleteRandomComment()
{
// Fetching a Random Comment
Comment comment;
using (var context = new DiscussionBoardContext())
{
// Get me a random comment
comment = context.Comments.FirstOrDefault();
}
using (var context = new DiscussionBoardContext())
{
context.Database.Log = Console.WriteLine;
// Note*
// We need to apprise this Context of the changes we would
// like to be made in the Database to the
// fetched Comment Object!
// Marking the object as Deleted for the Context to
// take action and fire a Delete Statement for the relevant
// Comment Object.
context.Entry(comment).State = EntityState.Deleted;
// Save the Updated Comment Object
context.SaveChanges();
Console.ReadKey();
}
}
private static void UpdateRandomCommentInDisconnectedState()
{
// Fetching a Random Comment
Comment comment;
using (var context = new DiscussionBoardContext())
{
// Get me a random comment
comment = context.Comments.FirstOrDefault();
}
// Update the data now
// This will mimick us fetching data and passing
// it to some sort of client - example a Web page
// for update.
// Mimicking Update the Web Client will do
comment.CommentDetail = "Comment Updated by: " +
"UpdateRandomCommentInDisconnectedState()" +
" Method on DateTime" + System.DateTime.Now.ToString();
// Now, the data HashSet to TransactionalBehavior saved.
using (var context = new DiscussionBoardContext())
{
context.Database.Log = Console.WriteLine;
// Note* This Context has NO IDEA of what has happened to the
// above Comment Object - It has no Knowledge that it has been
// Updated!
// We need to apprise it of the changes we have made to the
// Comment Object!
// Marking the object as Updated/Modified for the Context to
// take action and fire a Update Statement for the relevant
// Comment Object.
context.Entry(comment).State = EntityState.Modified;
// Save the Updated Comment Object
context.SaveChanges();
Console.ReadKey();
}
}