Skip to main content

Parametrii opționali - posibile probleme la versionare

Cu toții am auzit de parametrii opționali. VB suporta de foarte multa vreme. Începînd cu .NET 4.0 si C# suporta parametrii opționali.
Pe scurt parametrii opționali iți permit să ai parametrii la o metoda cu o valoarea default. A.i. acești parametrii pot fi omiși din apel.
public static void Example(string s1, string s2 = "2",
s3 = "3")
Apelul poate să fie de forma următoare:
Dar ce se întîmpla dacă avem doua versiune de assemply. In noua versiune va hotărați să adaugăm metoda:
public static void Example(string s1, string s3 = "3")

Dacă nu recompilam clientul, dar adaugăm noua versiune de assembly, metoda apelata o să fie tot cea din prima versiune. Dar ce se întîmpla dacă recompilați clientul cu a doua versiune de assembly? Fara nici o problema se va apela metoda adăugată in a doua versiune de assembly.

Acuma o să spuneți ca ceea ce se întîmpla este normal. 100% corect. Dar problema apare cu adevărat cînd adaugați un nou overload la o metoda cu parametrii opționali care are mai putini parametrii decît prima metoda, ca in exemplul de mai sus. Toate apelurile care spre metoda veche o să meargă spre noua metoda, ceea ce poate să ducă la un comportament neașteptat.


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 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…

GET call of REST API that contains '/'-slash character in the value of a parameter

Let’s assume that we have the following scenario: I have a public HTTP endpoint and I need to post some content using GET command. One of the parameters contains special characters like “\” and “/”. If the endpoint is an ApiController than you may have problems if you encode the parameter using the http encoder.
using (var httpClient = new HttpClient()) { httpClient.BaseAddress = baseUrl; Task<HttpResponseMessage> response = httpClient.GetAsync(string.Format("api/foo/{0}", "qwert/qwerqwer"))); response.Wait(); response.Result.EnsureSuccessStatusCode(); } One possible solution would be to encode the query parameter using UrlTokenEncode method of HttpServerUtility class and GetBytes method ofUTF8. In this way you would get the array of bytes of the parameter and encode them as a url token.
The following code show to you how you could write the encode and decode methods.