Develop Reference

Entity Framework 5 Update works only once per object / row

I'm using Entity Framework 5 with MySQL Database and just wanted to update a row attribute "user_loginstatus" between 0 and 1. The first time when I log in via client it updates just fine for the first attempt, after trying to update again it doesn't do anything with no exception.
I log in like this:
public async void LoginExecute()
{
// Checking Connection before etc...
if (await _dataService.IsLoginDataValidTask(UserObj.Username, md5))
{
Trace.WriteLine("LoginCommand Execute: Eingeloggt");
UserObj = await _dataService.GetUserDataTask(UserObj.Username);
await _dataService.SetUserStatusTask(UserObj.Id, 1);
await _dataService.WriteLog(UserObj.Id, "login", "Programm", GetLocalAdress());
Messenger.Default.Send(UserObj);
Messenger.Default.Send(new NotificationMessage("GoToMenuPage"));
}
else
{
// Error Stuff...
}
}
SetUserStatus Method in DataService Class
public Task SetUserStatusTask(int id, int status)
{
return Task.Factory.StartNew(() =>
{
try
{
var user = _entities.users.Find(id);
user.user_loginstatus = status;
_entities.SaveChanges();
}
catch (Exception ex)
{
Trace.WriteLine("DataService SetUserStatusTask: " + ex.Message);
}
});
}
GetUserData Method in DataService Class
public Task<User> GetUserDataTask(string username)
{
return Task.Factory.StartNew(() =>
{
try
{
var user = from us in _entities.users
where us.user_name.Equals(username)
select new User
{
Id = us.user_id,
Username = us.user_name,
FirstName = us.user_firstname,
LastName = us.user_lastname,
Gender = us.user_gender,
Email = us.user_mail,
Group = us.user_usergroup,
Avatar = us.user_avatar,
LoginStatus = 1
};
return user.FirstOrDefault();
}
catch (Exception ex)
{
Trace.WriteLine("DataService GetUserDataTask: " + ex);
return null;
}
});
}
So "users" is my table from the database and "User" / "UserObj" my custom Object.
With the Messenger (from MVVM Light) I just set via MainViewModel the Views, reset the unused ViewModels (ViewModel = new VieModel(...); or ViewModel = null;) and pass the current / logged in User Object.
With the same strategy I just Logout like this
public ICommand LogoutCommand
{
get
{
return new RelayCommand(async () =>
{
await _dataService.SetUserStatusTask(CurrentUser.Id, 0);
if(CurrentUser.Id > 0 && IsLoggedIn)
await _dataService.WriteLog(CurrentUser.Id, "logout", "Programm", GetLocalAdress());
IsLoggedIn = false;
CurrentUser = new User();
Messenger.Default.Send(new NotificationMessage("GoToLoginPage"));
});
}
}
So I can log in with my running Client so often I want, but the "user_loginStatus" only sets the changes the first login time to 1 and back to 0, but when I log out then and login back with the same user, it wont change it anymore. When I login (still same running Client) with another user it sets again the first time the "user_loginstatus" to 1 and back to 0 and then only again when I restart my Client..
What could I do wrong?

This is just basically from my comment regarding the original question:
I had similiar problems several times. Usually it is based on the fact that the entity you modified can't be validated properly and your dbContext fails without a proper exception because it still holds on to false entity. If this is the case you could circumvent this problem by using scoped contexts and embedding your data access operations in a using statement.
Alternatively you could try to explicitly tell EF that the entity has changes e.g.:
_entities.Entry(user).State = EntityState.Modified;
Regarding your other question:
In theory you shouldn't have to tell EF explicitly that the entity's values have changed. Change tracking should do that automatically. The only exception i could think of, is when you try to modify an entity that is explicitly not tracked anymore. When you call _entities.Find(id) it will look in the context if it finds the object with the matching primary key value and load it. Since you already modified this object before, the context will simply get the old object you already modified to set the login status the first time.
This "old" object is probably not tracked anymore and you have to tell EF explicitly that it has changed, by changing it's state from attached to modified.

in LoginExecute() you have UserObj, but in LogoutCommand() you have CurrentUser. Is it OK?

CRM 2013 how to create entity when error

I create custom error logger in CRM 2013 have functionality to save error information into CRM entity. I debug my code and find that my code works well. But the problem is when CRM rollback the transaction, the log entity also disappear. I want to know is it possible to create entity on catch block and still throw that error?
public void Execute(IServiceProvider serviceProvider)
{
try
{
...
}
catch (Exception ex)
{
IPluginExecutionContext context =
(IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
IOrganizationServiceFactory serviceFactory = (IOrganizationServiceFactory)serviceProvider.
GetService(typeof(IOrganizationServiceFactory));
IOrganizationService service = serviceFactory.CreateOrganizationService(Guid.Empty);
var log = new Log
{
Message = ex.Message
};
service.Create(log);
throw;
}
}

I found the other way to solve this issue. We can create new service to create new transaction outside the transaction being failed. Here some snippet if you want to do the same:
try
{
...
}
catch (Exception ex)
{
var HttpCurrentContext = HttpContext.Current;
var UrlBase = HttpCurrentContext.Request.Url.Host;
string httpUrl = #"http://";
if (HttpCurrentContext.Request.IsLocal)
{
UrlBase += ":" + HttpCurrentContext.Request.Url.Port;
}
if (!UrlBase.Contains(httpUrl))
{
UrlBase = httpUrl + UrlBase;
}
var UriBase = UriBuilder(UrlBase.ToLowerInvariant().Trim() + "/xrmservices/2011/organization.svc").Uri;
IServiceConfiguration<IOrganizationService> orgConfigInfo =
ServiceConfigurationFactory.CreateConfiguration<IOrganizationService>(UriBase);
var creds = new ClientCredentials();
using (_serviceProxy = new OrganizationServiceProxy(orgConfigInfo, creds))
{
// This statement is required to enable early-bound type support.
_serviceProxy.ServiceConfiguration.CurrentServiceEndpoint.Behaviors.Add(new ProxyTypesBehavior());
_service = (IOrganizationService)_serviceProxy;
var log = new Log
{
Message = ex.Message
};
_service.Create(NewLog);
}
throw;
}

Essentially, no. You cannot prevent that an exception rolls back the transaction. See a similar question on StackOverflow.
A common approach is to create a separate logging service that can store logs outside of the database transaction.
B.t.w. Dynamics CRM 2015 spring release introduces the capability to store logs regardless if your plugin is participating in a database transaction.

Multiple LINQ to SQL DataContext in Windows Phone 8

I create a mobile commerce in Windows Phone. This apps request JSON data from server and save them into local database. Lets say I have store, product, and category table. For the database, I initialize single DataContext for all CRUD operation, But this application can't run more than 1 operation in one time. For example, when I add some data into product table, I can't read any data from the others. I got Invalid Operation Exception. Then, I try to initialize a DataContext for every operation, I got "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext" Exception. Is there any solution for my DataContext problem? Here is a sample code of inserting category method.
public bool InsertAll(StoreTable Store, List<Simplz.ViewModel.Category> Categories)
{
bool value = true;
List<CategoryTable> _categories = new List<CategoryTable>();
using (SimplzDataContext DataContext = new SimplzDataContext(ConnectionString))
{
try
{
foreach (Simplz.ViewModel.Category p in Categories)
{
if (GetCategory(Store.ID, int.Parse(p.category_id)) == null)
{
_categories.Add(new CategoryTable(Store, p));
}
}
DataContext.Categories.InsertAllOnSubmit(_categories);
DataContext.SubmitChanges();
}
catch (Exception exc)
{
value = false;
Debug.WriteLine(exc.Message);
}
DataContext.Dispose();
}
return value;
}

When to Throw an Exception? When to Handle an Exception (Service Layer, Controller) where?

I rewritten my question as I think it was too wordy and maybe what I am trying to achieve was lost.
I written this code in notepad so it may have mistakes and some stuff maybe not well thoughout but it is to illustrate what I see my options are.
// I wrap all code send back from service layer to controller in this class.
public class ResponseResult
{
public ResponseResult()
{
Errors = new Dictionary<string, string>();
Status = new ResponseBase();
}
public void AddError(string key, string errorMessage)
{
if (!Errors.ContainsKey(key))
{
Errors.Add(key, errorMessage);
}
}
public bool IsValid()
{
if (Errors.Count > 0)
{
return false;
}
return true;
}
public Dictionary<string, string> Errors { get; private set; }
public ResponseBase Status { get; set; }
}
public class ResponseResult<T> : ResponseResult
{
public T Response { get; set; }
}
public class ResponseBase
{
public HttpStatusCode Code { get; set; }
public string Message { get; set; }
}
Option 1 (what I am using now)
//controller
public HttpResponseMessage GetVenue(int venueId)
{
if (venueId == 0)
{
ModelState.AddModelError("badVenueId", "venue id must be greater than 0");
if (ModelState.IsValid)
{
var venue = venueService.FindVenue(venueId);
return Request.CreateResponse<ResponseResult<Venue>>(venue.Status.Code, venue);
}
// a wrapper that I made to extract the model state and try to make all my request have same layout.
var responseResult = new ResponseResultWrapper();
responseResult.Status.Code = HttpStatusCode.BadRequest;
responseResult.Status.Message = GenericErrors.InvalidRequest;
responseResult.ModelStateToResponseResult(ModelState);
return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);
}
// service layer
public ResponseResult<Venue> FindVenue(int venueId)
{
ResponseResult<Venue> responseResult = new ResponseResult<Venue>();
try
{
// I know this check was done in the controller but pretend this is some more advanced business logic validation.
if(venueId == 0)
{
// this is like Model State Error in MVC and mostly likely would with some sort of field.
responseResult.Errors.Add("badVenueId", "venue id must be greater than 0");
responseResult.Status.Code = HttpStatusCode.BadRequest;
}
var venue = context.Venues.Where(x => x.Id == venueId).FirstOrDefault();
if(venue == null)
{
var foundVenue = thirdPartyService.GetVenue(venueId);
if(foundVenue == null)
{
responseResult.Status.Code = HttpStatusCode.NotFound;
responseResult.Status.Message = "Oops could not find Venue";
return responseResult;
}
else
{
var city = cityService.FindCity(foundVenue.CityName);
if(city == null)
{
city = cityService.CreateCity(foundVenue.CityName);
if(city.Response == null)
{
responseResult.Status.Code = city.Status.Code;
responseResult.Status.Message = city.Status.Message;
return responseResult;
}
CreateVenue(VenueId, city.Response, foundVenue.Name);
responseResult.Status.Code = HttpStatusCode.Ok;
// I don't think I would return a success message here as the venue being displayed back to the user should be good enough.
responseResult.Status.Message = "";
reponseResult.Response = foundVenue;
}
}
return responseResult;
}
}
catch (SqlException ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
responseResult.Status.Code = HttpStatusCode.InternalServerError;
responseResult.Status.Message = GenericErrors.InternalError;
// maybe roll back statement here depending on the method and what it is doing.
}
// should I catch this, I know it should be if you handle it but you don't want nasty messages going back to the user.
catch (InvalidOperationException ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
responseResult.Status.Code = HttpStatusCode.InternalServerError;
responseResult.Status.Message = GenericErrors.InternalError;
}
// should I catch this, I know it should be if you handle it but you don't want nasty messages going back to the user.
catch (Exception ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
responseResult.Status.Code = HttpStatusCode.InternalServerError;
responseResult.Status.Message = GenericErrors.InternalError;
}
return responseResult;
}
// another service layer.
// it is ResponseResult<City> and not city because I could have a controller method that directly calls this method.
// but I also have a case where my other method in another service needs this as well.
public ResponseResult<City> CreateCity(string CityName)
{
ResponseResult<City> responseResult = new ResponseResult<City>();
try
{
City newCity = new City { Name = "N" };
context.Cities.Add(newCity);
context.SaveChanges();
responseResult.Status.Code = HttpStatusCode.Ok;
responseResult.Status.Message = "City was succesfully added";
}
// same catch statmens like above
catch (SqlException ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
responseResult.Status.Code = HttpStatusCode.InternalServerError;
responseResult.Status.Message = GenericErrors.InternalError;
// maybe roll back statement here depending on the method and what it is doing.
}
return responseResult;
}
As you can see the methods are all wrapped in the status codes as they could be directly called by the controller being public. FindCity() and CreateVenue() could also have this wrapping.
Option 2
public HttpResponseMessage GetVenue(int venueId)
{
try
{
if (venueId == 0)
{
ModelState.AddModelError("badVenueId", "venue id must be greater than 0");
if (ModelState.IsValid)
{
var venue = venueService.FindVenue(venueId);
return Request.CreateResponse<ResponseResult<Venue>>(HttpSatusCode.Ok, venue);
}
// a wrapper that I made to extract the model state and try to make all my request have same layout.
var responseResult = new ResponseResultWrapper();
responseResult.Status.Code = HttpStatusCode.BadRequest;
responseResult.Status.Message = GenericErrors.InvalidRequest;
responseResult.ModelStateToResponseResult(ModelState);
return Request.CreateResponse<ResponseResult>(responseResult.Status.Code, responseResult);
}
catchcatch (SqlException ex)
{
// can't remember how write this and too tried to look up.
return Request.CreateResponse(HttpStatusCode.InternalServerError;, "something here");
}
}
public Venue FindVenue(int venueId)
{
try
{
// how to pass back business logic error now without my wrapper?
if(venueId == 0)
{
// what here?
}
var venue = context.Venues.Where(x => x.Id == venueId).FirstOrDefault();
if(venue == null)
{
var foundVenue = thirdPartyService.GetVenue(venueId);
if(foundVenue == null)
{
// what here?
}
else
{
var city = cityService.FindCity(foundVenue.CityName);
if(city == null)
{
city = cityService.CreateCity(foundVenue.CityName);
if(city == null)
{
// what here?
}
CreateVenue(VenueId, city.Response, foundVenue.Name);
}
}
return venue;
}
}
catch (SqlException ex)
{
// should there be a try catch here now?
// I am guessing I am going to need to have this here if I need to do a rollback and can't do it in the controller
// throw exception here. Maybe this won't exist if no rollback is needed.
}
return null;
}
public City CreateCity(string CityName)
{
// if it crashes something I guess will catch it. Don't think I need to rollback here as only one statement being sent to database.
City newCity = new City { Name = "N" };
context.Cities.Add(newCity);
context.SaveChanges();
return newCity;
}
As you see with option 2, I might still need to wrap it in try catches for rollbacks and I am not sure how to handle advanced business validation.
Also with catching everything in the controller and sending back vanilla objects(without my wrapper) I am unsure how to do fine grain HttpStatus codes(say like notFound,Create and such)

Sorry for the brief response, but here is my general rule - if an exception occurs which you expect might happen, deal with it - either by retrying or telling the user something went wrong and giving them options to fix it.
If an unexpected exception occurs, if it's something you can deal with (e.g a timeout which you can retry) try to deal with it, otherwise get out - just think what any MS app does - e.g. office - you get an apology that something went wrong and the app ends. It's better to end gracefully than to potentially corrupt data and leave things in a real mess.

This is an article with Java-specific concepts and examples, but the broad principles here are the way to go.
Distinguish between fault exceptions, which are catastrophic and unrecoverable, and contingency exceptions, which are very much recoverable. Let the faults "bubble" to the fault barrier, where you handle appropriately. For example, you might log the error, E-mail someone or send a message to a message queue, and present the user with a nice, informative error page.
Whatever you do, be sure to preserve all the exception information from the source.
Hope that helps.

Throw an exception wherever your code determines that something has gone wrong.
You always need to handle exceptions in methods which are called directly by the end-user. This is to cater for unexpected errors which your code doesn't have specific handling for. Your generic handling code would typically log the error and may or may not include letting the user know that an unexpected error has occurred.
But if there are errors which you can expect ahead of time, you'll often want to handle these lower down in the code, nearer to the point at which they occur, so that your application can "recover" from the error and continue.

I think exceptions are useful any time you need to return details of a failure from a method, whilst being able to use the ideal return type for the method you're calling.
You said in your question:
Now for me I try to return error messages back to the the controller
and try not to really catch anything in the controller.
If the service method is supposed to ideally return a Venue object, how do you return this potential error message back to the controller? an out parameter? change the return type to something which has an error message property on it?
If you're doing either of those options, I think you're reinventing the wheel... i.e. creating a way to return exception information when one already exists.
Finally, Exceptions are strongly typed representations of what went wrong. If you return an error message, then that is fine to send back to the user, but if you need to programatically do different things based on the details of the error, then you don't want to be switching on magic string.
For example, wouldn't it be handy to differentiate between authorization errors and not found errors so you can return the most appropriate http status code to the user?
Don't forget that the Exception class has a Message property you can simply return to the user if you want to use it that way

To make sure I understand the question, your are creating a web service and want to know when to handle and when to throw exceptions.
In this situation I would strongly recommend that you catch all exceptions. "Unhandled" exceptions are very bad form. On web sites they result in displays that range from meaningless to dangerous by exposing internal information that you do no want the public to see.
If this is a good sized program I suggest that you create your own MyException class which derives from System.Exception. The purpose of this is provide a place for you to add additional information specific to your application. Here are some typical things I like to add to my MyException classes:
An ID number that will help me find the location in the code where the problem occurred.
A "LogMessage" method that logs the exception, sometimes to the Windows Event Log. Whether or not you log and to which log you write depends on what you want recorded, and the severity of the situation.
An indicator that shows the exception has been logged so the above method will not log twice even if it gets called more than once.
Anything else that might be useful given the circumstance.
I also like to put the text of the messages in an external resource file, like an XML document, and key them to the error number that you assign. This allows you to change the error text to improve clarity without having to redeploy the application.
Catch all exceptions and create a new instance of your MyException type and put the original exception into inner exception property. Below the first level of my application, I always throw one of my MyException instances rather than the original exception.
At the top level (application level), NEVER let an exception go unhandled and never throw your own exception. A better way is to return an error code and message in your data contract. That way the client application will only get what you want them to see. The only exceptions they'll need to worry about are the ones outside your scope, i.e. configuration errors or communication failures. In other words if they are able to invoke your service and the network stays connected you should give them a response they can interpret.
Hope this helps.
PS I didn't include a sample exception as I am sure a little searching will find many. Post if you want me to put up a simple sample.

Use try catch at all levels and bubble it up. Optionally, log the error in a file or database. I use text file - tab delimited. Capture at each level
1. Module Name (Use C# supplied methods to get this)
2. Method Name
3. Code Being Executed (User created - "Connecting to database")
4. Error Number
5. Error Description
6. Code Being Executed (User created - "Accessing database")
7. Error Number for the end user
8. Error Description for the end user
Additionally, I also pass a unique identifier like - Session Id in case of Web, Logged in User Id, User Name (if available)
I always have the Exception catch block. In here I set the error number as -0 and the message from the exception object as the error description. If it is SQL Server related - I capture SQL Exception. This generates an error number - I use that.
I want to extend this some more though.

Context message for UPDATE is not working

I am working on a CRM Dynamics Plugin. There is a field on custom entity named "email". I want to make sure that for two entity records email addresses should be unique. For that purpose I have written following code:
public class Class1 : IPlugin
{
public void Execute(IServiceProvider serviceProvider)
{
// Obtain the execution context from the service provider.
Microsoft.Xrm.Sdk.IPluginExecutionContext context = (Microsoft.Xrm.Sdk.IPluginExecutionContext)
serviceProvider.GetService(typeof(Microsoft.Xrm.Sdk.IPluginExecutionContext));
// Get a reference to the organization service.
IOrganizationServiceFactory factory =
(IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
IOrganizationService service = factory.CreateOrganizationService(context.UserId);
// The InputParameters collection contains all the data passed in the message request.
if (context.InputParameters.Contains("Target") &&
context.InputParameters["Target"] is Entity)
{
Entity entity = (Entity)context.InputParameters["Target"];
//</snippetAccountNumberPlugin2>
// Verify that the target entity represents an account.
// If not, this plug-in was not registered correctly.
if (context.MessageName.ToUpper() == "CREATE")
{
if (entity.LogicalName == "new_assignment1entity")
{
try
{
QueryExpression query = new QueryExpression("new_assignment1entity");
query.ColumnSet.AddColumns("new_email");
EntityCollection result1 = service.RetrieveMultiple(query);
foreach (var a in result1.Entities)
{
int size = result1.Entities.Count;
if (a.Attributes["new_email"].ToString().Equals(entity["new_email"]))
throw new InvalidPluginExecutionException("Duplicate Email found!");
}
}
catch (FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault>)
{
//You can handle an exception here or pass it back to the calling method.
throw new InvalidPluginExecutionException("Some problem occurred while Querying Records!");
}
}
}
else if (context.MessageName.ToUpper() == "UPDATE")
{
if (entity.LogicalName == "new_assignment1entity")
{
try
{
QueryExpression query = new QueryExpression("new_assignment1entity");
query.ColumnSet.AddColumns("new_email");
EntityCollection result1 = service.RetrieveMultiple(query);
foreach (var a in result1.Entities)
{
int size = result1.Entities.Count;
if (a.Attributes["new_email"].ToString().Equals(entity["new_email"]))
throw new InvalidPluginExecutionException("Duplicate Email found!");
}
}
catch (FaultException<Microsoft.Xrm.Sdk.OrganizationServiceFault>)
{
//You can handle an exception here or pass it back to the calling method.
throw new InvalidPluginExecutionException("Some problem occurred while Querying Records!");
}
}
}
}
}
}
When User creates a new entity record with duplicate email address this code works and shows a dialog box printing error message. But when User edit an existing record (update and existing record) and makes the email address duplicate then this code does not work and updated record with duplicated email address saved.
I am guessing that Context message with UPDATE else part is not working.
Please help me out.

It's not really worth trying to debug this as unfortunately you are going about this in a horribly inefficient way. (Though the most likely cause is the way you are querying being subject to a "feature" of CRM which means you are not querying all the records you think you are).
In short, your code says:
Get me ALL(*) instances of the new_assignment1entity entity
Look at each record until I find one with an email address that matches (case-sensitive) the value just provided in the update
Throw an exception when you encounter the first exact match (otherwise continue with the transaction)
Mains points of note:
QueryExpression will only return the maximum first 5000 records in CRM
You should be filtering your query to only return new_assignment1entity records where the new_email attribute matches the provided value
String.Equals(string) is case-sensitive so to truly check for a duplicate, you should convert the case of each value
Your size variable serves no purpose
Your code will throw an exception if the new/updated record has no value for new_email. You should check that the attribute exists before attempting to access it

I resolved this issue. The problem why only Create execution flow was running and not Update is that I had only registered the plugin for create message step. To overcome this issue, I added a new step in same plugin and registered it with update message as show in following screenshot:
And it worked like charm.
Apart from this, #GregOwens mentioned very helpful points.These should follow as best practices in CRM Development.