Category: .NET

Asynchronous code and exceptions

There are 2 kinds of coding when handling asynchronous code.

The first one is  calling Result:

<

The second is async /await

public async Task<bool> TwoTask() {

//code

await Task.WhenAll(file, console);
return file.Result & console.Result;

}

As such, we will have 2 intercepting code.

For the first one we will catch AggregateException

try
            {
                Console.WriteLine(t.TwoTask().Result);
            }
            catch (AggregateException ex)
            {
                Console.WriteLine("Aggregate number of exceptions :"+ex.InnerExceptions.Count);
            }

For the second one we will catch the FIRST task  exception  ( or , more generic , Exception ) – and see what other tasks have been doing

try

try
            {
                await Task.WhenAll(file, console);
                return file.Result & console.Result;
            }
            catch (ArgumentException ex)
            {
                Console.WriteLine("Exception is " + ex.Message);
                
                if (file.IsFaulted)
                {
                    Console.WriteLine("file is faulted exceptions :" + file.Exception.InnerExceptions.Count);
                    
                }
                if (console.IsFaulted)
                {
                    Console.WriteLine("console is faulted exceptions :" + console.Exception.InnerExceptions.Count);
                }
                
                throw;
            }

Maybe it is better when you see a video demo: Async await and exceptions at https://youtu.be/1a9s74IfSE8

Async / await transformation and pitfalls


    /// <summary>
    /// please read first http://blog.stephencleary.com/2012/02/async-and-await.html
    /// </summary>

Let’s say you want to transform this code to async / await

public bool TwoTask()
        {
            var file= WriteToFile();
            var console= ReadConsole();
            return file & console;
        }

The first version is


public async Task<bool> TwoTask()
        {
            var file=await WriteToFile();
            var console = await ReadConsole();
            return file & console;
        }

Why is not good ? Because it executes in serial the file, and then the console code

The good version is


public async Task<bool> TwoTask()
        {
            var file=WriteToFile();
            var console = ReadConsole();
            await Task.WhenAll(file, console);
            return file.Result & console.Result;
        }

You can see in action at https://youtu.be/02oO0YaTEyM

MVC planning poker–part 7

The latest 2 cases are

Use Case 5: Round reset
Moderator enters a round name (?) .
Participants choose a value.
Host press "reset round " and a fresh new round is created
The old one is not saved

Use Case 6: Round save
After a round is saved, the users can see the history round names and picked value
They can see also a total

 

There is not so more implementation – just save in the memory  a list and retrieve.

Next time we will be thinking about persistence – how this affect the structure of the application

Entity Framework 6 Record and play use : Unit Testing ( part 2 of 5)

 

Part 1 : What is EF record and play : http://msprogrammer.serviciipeweb.ro/2014/11/29/entity-framework-6-record-and-play-1-of-5/ 

Part 2: EF Record and play use: Testing : http://msprogrammer.serviciipeweb.ro/2014/12/08/entity-framework-6-record-and-play-use-unit-testing-part-2-of-5/

Part 3: EF Record and play use: Make demo: http://msprogrammer.serviciipeweb.ro/2014/12/14/entity-framework-6-record-and-play-use-making-demos-part-3-of-5/ 

Part 4: EF Record and play use: Record user Sql when a bug occurs: http://msprogrammer.serviciipeweb.ro/2014/12/26/ef-record-and-play-use-recording-user-sql-when-a-bug-occurred-part-4-of-5/

Part 5: EF record and play: conclusions: http://msprogrammer.serviciipeweb.ro/2015/01/05/ef-record-and-play-conclusions/

 

Let’s suppose that we have a program that have Departments and Employees.

And we want to make sure that, when we add an employee, the department must exists.

We can ensure this from database ( by foreign key) but we can pro-actively search for the department and throw a more meaningful validation .

More, I like more validation than errors.

So, let’s suppose that in the Validation for the Employee we must check in the database for the IdDepartment to see if there is such a department.

How could we make a test for that runs without a database ?

With some trick:  we first Record with a database  – then we can Play the file – and we do not need anymore the database. The test is self contained. 

 

Let’s see in action here

 

Database.SetInitializer<ContextForDatabase>(null);
            #region set record EF
            var record = new InterceptionRecordOrPlay(@"VerifyIValidatableWorks.zip", ModeInterception.Play);

            DbInterception.Add(record);
            #endregion
            var e= new Employee();
            e.ValidateEmployee = true;
            e.IDDepartment = 60000;
            var err= e.Validate(null).ToArray();
            Assert.IsNotNull(err);
            Assert.AreEqual(1, err.Length);

Source code is available at  https://github.com/ignatandrei/EFRecordAndPlay/wiki/

 

There is also a NuGet package at https://www.nuget.org/packages/EFRecordAndPlay/

Entity Framework 6 Record and play – 1 of 5

 

Part 1 : What is EF record and play : http://msprogrammer.serviciipeweb.ro/2014/11/29/entity-framework-6-record-and-play-1-of-5/ 

Part 2: EF Record and play use: Testing : http://msprogrammer.serviciipeweb.ro/2014/12/08/entity-framework-6-record-and-play-use-unit-testing-part-2-of-5/

Part 3: EF Record and play use: Make demo: http://msprogrammer.serviciipeweb.ro/2014/12/14/entity-framework-6-record-and-play-use-making-demos-part-3-of-5/ 

Part 4: EF Record and play use: Record user Sql when a bug occurs: http://msprogrammer.serviciipeweb.ro/2014/12/26/ef-record-and-play-use-recording-user-sql-when-a-bug-occurred-part-4-of-5/

Part 5: EF record and play: conclusions: http://msprogrammer.serviciipeweb.ro/2015/01/05/ef-record-and-play-conclusions/

 

Entity Framework Record And Play

With this helper you can record and then play the actions in Entity Framework(>= 6).

For recording actions just reference the dll and use

DbInterception.Add(new InterceptionRecordOrPlay(@"a.zip", ModeInterception.Record)); 

(Note: For ASP.NET you will use Server.MapPath("~/a folder that supports write/namefile.zip")

For replay use

DbInterception.Add(new InterceptionRecordOrPlay(@"a.zip", ModeInterception.Play));

This can be use for

  1. Unit Testing
  2. Making demos
  3. Recording user actions when a bug occurred

 

Source code is available at  https://github.com/ignatandrei/EFRecordAndPlay/wiki/

and has also a test 😉

There is also a NuGet package at https://www.nuget.org/packages/EFRecordAndPlay/ 

 

image

Traceability – conclusion – part 7 of 7

Those were previous posts:

Traceability in .NET – 1 of 7

Traceability in .NET–1.0.*–part 2 of 7

Tracebility in .NET -source control – part 3 of 7

Traceability in .NET–.tt files–add build date– part 4 of 7

Traceability in .NET–.tt files–add changeset – part 5 of 7

.TT – add more informations(.NET version , build ) – part 6 of 7

As conclusions:
You can put 1.0.* and Visual Studio will take care about incrementing the version- but it will be difficult to identify the build date.
Or you can use Team Foundation Server to put dates into the version
Or you can use .TT files – in simple or advanced way – and make automatically the version

The source code is at https://traceabilitydemo.codeplex.com/

The entire video you can find at http://www.youtube.com/playlist?list=PL4aSKgR4yk4M3BgSjQvryEFjwq_sGUgh7

The entire written series is here: http://msprogrammer.serviciipeweb.ro/wp-content/uploads/traceability.pdf

.TT – add more informations(.NET version , build ) – part 6 of 7

As you can see from the previous chapter, we have added to the AssemblyDescription more informations – like .NET version, build configuration , and more

You can see those with an explorer add-on http://www.codeproject.com/Articles/118909/Windows-7-File-properties-Version-Tab-Shell-Extens

Video : http://youtu.be/A_qSdVV93qk

Demo project here : https://traceabilitydemo.codeplex.com/releases/view/132231

Source code here : https://traceabilitydemo.codeplex.com/SourceControl/changeset/view/110446

Traceability in .NET–.tt files–add changeset – part 5 of 7

We wish to add , from the .tt file , the id of the last TFS checkin. For this purpose we will connect to TFS and we will investigate in the current project the latest change.

We will use the facility of .tt file to connect to the host and ask for various features ( such as TFS )

The .tt file code is:

  

<#@ template debug="false" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ assembly name="Microsoft.VisualStudio.Shell.Interop.8.0" #>
<#@ assembly name="EnvDTE" #>
<#@ assembly name="EnvDTE80" #>


<#@ assembly name="Microsoft.VisualStudio.TeamFoundation.VersionControl" #>
<#@ assembly name="Microsoft.TeamFoundation.Client"#>
<#@ assembly name="Microsoft.TeamFoundation.Common"#>
<#@ assembly name="Microsoft.TeamFoundation"#>
<#@ assembly name="Microsoft.TeamFoundation.WorkItemTracking.Client"#>
<#@ assembly name="Microsoft.TeamFoundation.VersionControl.Client"#>
<#@ assembly name="Microsoft.TeamFoundation.ProjectManagement"#>


<#@ import namespace="Microsoft.TeamFoundation.Client"#>
<#@ import namespace="Microsoft.TeamFoundation.VersionControl.Client"#>


<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Text.RegularExpressions" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="EnvDTE" #>
<#@ import namespace="EnvDTE80" #>
<#@ output extension=".cs" #>
<#
DTE dte=null;
var serviceProvider = Host as IServiceProvider;
    if (serviceProvider != null) {
        dte = serviceProvider.GetService(typeof(DTE)) as DTE;
    }
	if (dte == null) {
        throw new Exception("generate build number can only execute through the Visual Studio IDE");
		}
ProjectItem projectItem = dte.Solution.FindProjectItem(Host.TemplateFile);
int netVersion=0;

var proj=projectItem.ContainingProject;
var configmgr = proj.ConfigurationManager;
var config = configmgr.ActiveConfiguration;
string regex=@"^.+?Version=v(?<version>\-?\d+\.\d+).*?$";
var options = RegexOptions.Multiline;
string input= proj.Properties.Item("TargetFrameworkMoniker").Value.ToString();
	
MatchCollection matches = Regex.Matches(input,regex,options);
foreach (Match match in matches)
{
		
    netVersion = (int)(double.Parse(match.Groups["version"].Value)*100);
		
}


string filePath = proj.FullName;
string dirPath = System.IO.Path.GetDirectoryName(filePath);
var wsInfo = Microsoft.TeamFoundation.VersionControl.Client.Workstation.Current.GetLocalWorkspaceInfo(filePath );
 
 // Get the TeamProjectCollection and VersionControl server associated with the
 // WorkspaceInfo
 var tpc = new TfsTeamProjectCollection(wsInfo.ServerUri);
 var vcServer = tpc.GetService<VersionControlServer>();
 
 // Now get the actual Workspace OM object
 var ws = vcServer.GetWorkspace(wsInfo);
 
 // We are interested in the current version of the workspace
 var versionSpec = VersionSpec.Latest;
 
 var historyParams = new QueryHistoryParameters(dirPath, RecursionType.Full);
 historyParams.ItemVersion = versionSpec;
 historyParams.VersionEnd = versionSpec;
 historyParams.MaxResults = 1;
 
 var changeset = vcServer.QueryHistory(historyParams).FirstOrDefault();


 var dt = DateTime.Now;
var userName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
userName = userName.Split('\\').Last();

 #>
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

// General Information about an assembly is controlled through the following 
// set of attributes. Change these attribute values to modify the information
// associated with an assembly.
[assembly: AssemblyTitle("BuildTraceabilityDemo")]
//http://www.codeproject.com/Articles/118909/Windows-7-File-properties-Version-Tab-Shell-Extens
[assembly: AssemblyDescription("BuildDate,<#=dt.ToString("yyyyMMdd_HHmmss")#>\r\n<#=proj.Properties.Item("TargetFrameworkMoniker").Value.ToString()#>\r\nBuild by,<#=userName#>\r\nConfig,<#=config.ConfigurationName#>,\r\nChangeset,<#=changeset.ChangesetId#>")]
[assembly: AssemblyConfiguration("")]
[assembly: AssemblyCompany("")]
[assembly: AssemblyProduct("BuildTraceabilityDemo")]
[assembly: AssemblyCopyright("Copyright ©  <#= dt.Year#>")]
[assembly: AssemblyTrademark("")]
[assembly: AssemblyCulture("")]

// Setting ComVisible to false makes the types in this assembly not visible 
// to COM components.  If you need to access a type in this assembly from 
// COM, set the ComVisible attribute to true on that type.
[assembly: ComVisible(false)]

// The following GUID is for the ID of the typelib if this project is exposed to COM
[assembly: Guid("75ff7863-cb83-4d9b-80de-4a0de2781918")]

// Version information for an assembly consists of the following four values:
//
//      Major Version
//      Minor Version 
//      Build Number
//      Revision
//
// You can specify all the values or you can default the Build and Revision Numbers 
// by using the '*' as shown below:
// [assembly: AssemblyVersion("1.0.*")]
[assembly: AssemblyVersion("1.0.0.0")]
[assembly: AssemblyFileVersion("1.<#=dt.Year#>.<#=dt.Month#>.<#=dt.Day#>")]


   

Video : http://youtu.be/A_qSdVV93qk

Demo project here : https://traceabilitydemo.codeplex.com/releases/view/132231

Source code here : https://traceabilitydemo.codeplex.com/SourceControl/changeset/view/110446

Andrei Ignat weekly software news(mostly .NET)

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