Skip to main content

One way to persist objects in isolated storage

In unele cazuri avem nevoie sa stocam date in isolated storage. In cazul in care numarul de date pe vrem sa le stocam nu este foarte mare, putem sa le serializam direct si sa le salvam sub forma unui fisier in isolated storage.
In exemplul de mai jos, datele le-am serializat folosind DataContractSerializer. Din aceasta cauta, clasele pe care vrem sa le salvam trebuie sa fie decorate cu atributul DataContract, iar fiecare proprietate pe care dorim sa o salvam trebuie decorata cu atributul DataMember.
[DataContract]
class Foo
{
   [DataMember]
   public string Name { get; set; }
   public int Age {get; set; }
}
In exemplul dat mai sus o sa salvam doar proprietatea Name.
Mai jos puteti sa gasiti o clasa generica care salveaza un obiect dat. In metodele Save si Load as fi putut sa trimit ca si parametru numele la fisier, dar am ales ca numele de fisier sa se genereze pe baza tipului. Se poate si in alte moduri.
public class IsolatedStorageRepository<TItem>
   {
       public void Save(TItem item)
       {
           using (IsolatedStorageFileStream fileStream = IsolatedStorageFile.GetUserStoreForApplication()
                                                           .OpenFile(GetFileName(), FileMode.Create))
           {
               new DataContractSerializer(typeof(TItem))
                       .WriteObject(fileStream, item);
           }
       }
       public TItem Load()
       {
           IsolatedStorageFile storageFile = IsolatedStorageFile.GetUserStoreForApplication();
           if (!storageFile.FileExists(filename))
           {
               return default(TItem);
           }

           using (IsolatedStorageFileStream fileStream = storageFile.OpenFile(GetFileName, FileMode.Open))
           {
               return (TItem)new DataContractSerializer(typeof(TItem)).ReadObject(fileStream);              
           }
       }

       private string GetFileName()
       {
           string typeName = typeof (TItem).ToGenericFullName();
           typeName = typeName.Replace('<', '_');
           typeName = typeName.Replace('>', '_');

           return typeName;
       }
   }
Metoda ToGenericFullName imi returneaza numele unui obiect. Pentru a vedea implementarea acestei clase puteti sa intrati pe link-ul urmator: http://vunvulearadu.blogspot.com/2012/03/how-to-get-friendly-format-for.html
List<Foo> fooList = new List<Foo>();
// populate list
IsolatedStorageRepository repository = new IsolatedStorageRepository<List<Foo>>();
// Save list
repository.Save(fooList);
// Load list
repository.Load();
Solutia se poate implementa in diferite moduri. Aceasta este doar o varianta.
Enjoy!.

Comments

Popular posts from this blog

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

Entity Framework (EF) TransactionScope vs Database.BeginTransaction

In today blog post we will talk a little about a new feature that is available on EF6+ related to Transactions.
Until now, when we had to use transaction we used ‘TransactionScope’. It works great and I would say that is something that is now in our blood.
using (var scope = new TransactionScope(TransactionScopeOption.Required)) { using (SqlConnection conn = new SqlConnection("...")) { conn.Open(); SqlCommand sqlCommand = new SqlCommand(); sqlCommand.Connection = conn; sqlCommand.CommandText = ... sqlCommand.ExecuteNonQuery(); ... } scope.Complete(); } Starting with EF6.0 we have a new way to work with transactions. The new approach is based on Database.BeginTransaction(), Database.Rollback(), Database.Commit(). Yes, no more TransactionScope.
In the followi…

Fundamental Books of a Software Engineer (version 2018)

More then six years ago I wrote a blog post about fundamental books that any software engineer (developer) should read. Now it is an excellent time to update this list with new entries.

There are 5 different categories of books, that represent the recommended path. For example, you start with Coding books, after that, you read books about Programming, Design and so on.
There are some books about C++ that I recommend not because you shall know C++, only because the concepts that you can learn from it.

Coding

Writing solid codeCode completeProgramming Pearls, more programming pearls(recommended)[NEW] Introduction to Algorithms

Programming

Refactoring (M. Fowler)Pragmatic ProgrammerClean code[NEW] Software Engineering: A Practitioner's Approach[NEW] The Mythical Man-Month[NEW] The Art of Computer Programming

Design

Applying UML and Patterns (GRASP patterns)C++ coding standards (Sutter, Alexandrescu)The C++ programming language (Stroustrup, Part IV)Object-oriented programming (Peter Coad)P…