Skip to main content

Cum sa obtinem numele unei proprietati folosind lambda expression

Nu odată ne-am lovit de acesta problema. Cum sa transmit numele unei proprietăți ca si string, fara sa fiu obligat in cazul unei redenumiri sa nu trebuiasca sa caut prin tot codul.
O solutie este crearea unei clase de mapare, dar aceasta trebuie sa fie tot timpul adusa la zi. O alta solutie este sa folosim reflection. Putem sa ne cream un helper care sa rezolve problema, dar lucrurile se complica cand vrem rezultatul sa fie sub forma: "proprietateParinte.proprietateCopil".
Cei care folosesc MVC stiu ca acesta vine in ajutorul programatorilor cu ExpressionHelper.GetExpressionText(exprisieLambda). Acesta metoda este des folosita cand se lucreaza cu ViewModel. Dar ce ne facem daca nu suntem intr-o aplicatie ASP.NET MVC?
O solutie este sa luam expresia lambda si sa o descompunem. Prin acest mecanism putem sa iteram prin fiecare parte din expresie. Prin intermediul propietatii Body putem sa obtinem body-ul expresiei, iar in functie de tipul expresiei putem sa stim pe ce pozitie ne aflam.
    public class PropertyNameHelper
private const string Delimiter = ".";

public static string For<T>(Expression<Func<T, object>> expression)
where T:class
var body = expression.Body;
return GetPropertyName(body);

pprivate static string GetPropertyName(Expression expression)
if (expression is MemberExpression)
var memberExp = (MemberExpression)expression;
return memberExp.Expression.NodeType == ExpressionType.MemberAccess
? string.Format("{0}{1}{2}",GetPropertyName(memberExp.Expression),Delimiter,memberExp.Member.Name)
: memberExp.Member.Name;
if (expression is UnaryExpression)
var unaryExp = (UnaryExpression)expression;
if (unaryExp.NodeType == ExpressionType.Convert)
return GetPropertyName(unaryExp.Operand);

throw new Exception(string.Format("The member {0} cannot be found.", expression));

throw new Exception(string.Format("The member {0} could not been determined.", expression));
Putem sa obținem numele la proprietate astfel:
PropertyNameHelper.For<Page>(s => s.Cache.Count);


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 …

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

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.


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


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


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