savechanges

Paraphrasing from this MSDN documentation ... An INSERT statement is generated by the Entity Framework and executed on the data source when SaveChanges is called on the ObjectContext. If the INSERT operation succeeds, server-generated values are written back to the ObjectStateEntry. When AcceptChanges is called automatically at the end of the SaveChanges execution, a permanent EntityKey is computed by using the new server-generated values. This does not seem to be occurring in my code. When I call ObjectContext.SaveChanges() , an UpdateException is thrown with InnerException.Message value:

I've got a WPF application with a Treeview control. When the user clicks a node on the tree, other TextBox, ComboBox, etc. controls on the page are populated with appropriate values. The user can then make changes to those values and save his or her changes by clicking a Save button. However, if the user selects a different Treeview node without saving his or her changes, I want to display a warning and an opportunity to cancel that selection. MessageBox: Continue and discard your unsaved changes? OK/Cancel http://img522.imageshack.us/img522/2897/discardsj3.gif XAML... <TreeView Name=

string[] usersToAdd = new string[] { "asd", "asdert", "gasdff6" }; using (Entities context = new Entities()) { foreach (string user in usersToAdd) { context.AddToUsers(new User { Name = user }); } try { context.SaveChanges(); //Exception thrown: user 'gasdff6' already exist. } catch (Exception e) { //Roll back all changes including the two previous users. } Or maybe this is done automatically, meaning that if error occurs, committing changes are canceled for all the changes. is it? Shimmy OK I created a sample a application like the example from the the question and afterwords I checked in the

I'd like to be able to save the current canvas' state to a server-side database, probably as a JSON string, and then later restore it with loadFromJSON . Typically, this is easily accomplished using: var canvas = new fabric.Canvas(); function saveCanvas() { // convert canvas to a json string var json = JSON.stringify( canvas.toJSON() ); // save via xhr $.post('/save', { json : json }, function(resp){ // do whatever ... }, 'json'); } And then function loadCanvas(json) { // parse the data into the canvas canvas.loadFromJSON(json); // re-render the canvas canvas.renderAll(); // optional canvas