[Tips] Database NULL to Zero

Oracle	SELECT NVL(col, 0 ) FROM mytable
SQL Server	SELECT ISNULL(col, 0 ) FROM mytable
MySQL	SELECT IFNULL(col, 0) AS column_name FROM mytable

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AI means everyone can now be a programmer(?)

Is it that easy?

Assuming you are not a developer and want to create an app to take screenshots on macOS.

You started to ask questions to AI and installed developer tools. Now you are ready for development.

Gemini

How to take a screenshot on macos xcode using swift?



You paste the code to XCode and see an error!


Ask Gemini to provide another solution.

The code you provided in swift didn't work. Suggest another swift way to capture a screenshot.

Gemini gives an apology and suggests another solution.



Let's see in XCode.



Can you see a strange code that contains Arabic letters?

guard let contentFilter = SCC محتوى الشاشة(sharingMode: .none) else { return nil }

You want to switch to ChatGPT to accomplish this easy task with the same prompt. 👇

ChatGPT

You paste the code provided by ChatGPT. Again, there is a problem in the code!



context.makeCurrent() didn't work. Is there any other way?



You pasted this code, and it worked! After a few trials, now think you are a programmer.

What will you do if you see CGDisplayCreateImage(_:) is deprecated?

So you keep asking for alternative ways, and you learn that there is a shiny framework named ScreenCaptureKit.

I recommend trying to ask both Gemini and ChatGPT to take a screenshot using ScreenCaptureKit. I tried, on several attempts, AI suggested wrong code each time.

Then you will decide how easy programming is!

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How to stream image from generic handler

This article provides an example of streaming images from a generic handler in .NET.

If you store your images in a database table as byte[] then you can utilize a handler to display them in a data grid.

The process involves sending a request to the handler (.ashx) page, retrieving the image, and then displaying it.

In the given example, we have a grid that stores IDs in one column and displays the corresponding images in another column using an asp:ImageField.

Create a generic handler that streams image. In this example ImageField requests image from getFaceImage.ashx by DataImageUrlField parameter in DataImageUrlFormatString format

public void ProcessRequest(HttpContext context)
{
    int id;

    if (context.Request.QueryString["id"] != null)
    {
        id = Convert.ToInt32(context.Request.QueryString["id"]);

        if (id > 0)
        {
            context.Response.ContentType = "image/jpeg";

            Stream strm = new MemoryStream();
            GetImage(id).Save(strm, ImageFormat.Jpeg);
            strm.Position = 0;

            byte[] buffer = new byte[4096];
            int byteSeq = strm.Read(buffer, 0, 4096);
            while (byteSeq > 0)
            {
                context.Response.OutputStream.Write(buffer, 0, byteSeq);
                byteSeq = strm.Read(buffer, 0, 4096);
            }
        }
    }
    else
        return;
}

public Image GetImage(int id)
{
    //Make appropriate calls for image according to id
    //...

    //return the image
    return new Bitmap("");
}

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Gitlab with Visual Studio 2022

Gitlab extension is not available for Visual Studio 2022.

VS Marketplace: GitLab Extension for Visual Studio
You can login any of your favorite GitLab servers and start your great job!
The GitLab Extension for Visual Studio provides GitLab integration in Visual Studio 2015/2017/2019.

In VS 2022, I created a new project and added to local git on user interface.

I also created an empty project on gitlab with the same name.

In gitlab project homepage it helps you what to do.

  cd existing_repo

  git remote add origin https://gitlab.com/git_username/project.git

  git branch -M main

  git push -uf origin main

I switched to command line and run commands above.

When you push the project to remote repository git shows a window for authentication.

I selected browser login and git command got credentials from browser.

C:\project>git push -uf origin main
info: please complete authentication in your browser...
Enumerating objects: 1718, done.
Counting objects: 100% (1718/1718), done.
Delta compression using up to 4 threads
Compressing objects: 100% (1688/1688), done.
Writing objects: 100% (1718/1718), 35.76 MiB | 540.00 KiB/s, done.
Total 1718 (delta 470), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (470/470), done.
remote: GitLab: You are not allowed to force push code to a protected branch on this project.
To https://gitlab.com/git_username/project.git
 ! [remote rejected] main -> main (pre-receive hook declined)
error: failed to push some refs to 'https://gitlab.com/git_username/project.git'

The problem was VS created a branch named master, but in gitlab branch name was main.

I created a new branch named master on gitlab.

In command line switch to branch named master and push project to master.

C:\projectO>git branch -M master

C:\project>git push -uf origin master
Enumerating objects: 1718, done.
Counting objects: 100% (1718/1718), done.
Delta compression using up to 4 threads
Compressing objects: 100% (1688/1688), done.
Writing objects: 100% (1718/1718), 35.76 MiB | 561.00 KiB/s, done.
Total 1718 (delta 470), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (470/470), done.
remote:
remote: To create a merge request for master, visit:
remote:   https://gitlab.com/git_username/project/-/merge_requests/new?merge_request%5Bsource_branch%5D=master
remote:
To https://gitlab.com/git_username/project.git

You can create a merge request in gitlab to push master branch into main.

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Windows 10 window border change

Problem

Losing title bar when multiple windows overlap, finding drag position becomes harder.

Solution

>Windows > Settings > Colors

Select "Title bars and windows borders".

Windows Activation Issue

If Windows is not activated you can not change color settings.

We can enable window borders by regedit commands.

reg add "HKEY_CURRENT_USER\Software\Microsoft\Windows\DWM" /v "ColorPrevalence" /t REG_DWORD /d "1" /f

reg add "HKEY_CURRENT_USER\Software\Microsoft\Windows\DWM" /v "AccentColor" /t REG_DWORD /d "7439985" /f

reg add "HKEY_CURRENT_USER\Software\Microsoft\Windows\DWM" /v "AccentColorInactive" /t REG_DWORD /d "13882323" /f

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[Tips] Random string generators C#

Testing 2 different Random string generators.

void Main()
{
 for(int i=0;i<10;i++){
  Console.WriteLine("GetRandomString: " + GetRandomString(8));
 }
 for(int i=0;i<10;i++){
  Console.WriteLine("GetRandomFileName: " + GetRandomFileName());
 } 
}

public static string GetRandomString(int length)
{
    Random random = new Random();
    const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    return new string(Enumerable.Repeat(chars, length)
      .Select(s => s[random.Next(s.Length)]).ToArray());
}

public static string GetRandomFileName()
{
    string path = Path.GetRandomFileName();
    path = path.Replace(".", ""); // Remove period.
    return path;
}

Result

GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomString: tpZIDi0C
GetRandomFileName: smb1u03pvyf
GetRandomFileName: 2ccre5kihis
GetRandomFileName: 24thz5is1pj
GetRandomFileName: ni0z42lexag
GetRandomFileName: 1u11tcvd3qv
GetRandomFileName: vtiqp2sevwy
GetRandomFileName: y2jhumy1hcx
GetRandomFileName: 5o0gsyronpk
GetRandomFileName: m0zva3mhdfn
GetRandomFileName: 2a2dzcdkpbl

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Failed to install Intel HAXM

When installing Android SDK Platform-Tools on Windows you may see following error:

Running Intel® HAXM installer Failed to install Intel HAXM. 
For details, please check the installation log: HAXM installation failed. To install HAXM follow the instructions found at: 
 https://software.intel.com/android/articles/installation-instructions-for-intel-hardware-accelerated-execution-manager-windows 
 
This computer does not support Intel Virtualization Technology (VT-x) 
 or it is being exclusively used by Hyper-V. 
 
HAXM cannot be installed. Please ensure Hyper-V is disabled in Windows Features, 
 or refer to the Intel HAXM documentation for more information.

I will list 3 different options.

1. Program and Features

Be sure Hyper-V not marked. If installed uncheck it.

2. Command line (CMD)

dism.exe /Online /Disable-Feature:Microsoft-Hyper-V

or

bcdedit /set hypervisorlaunchtype off

3. Device Guard and Credential Guard hardware readiness tool

Download tool, unzip and open powershell window.

First change execution policy.

PS C:\temp\dgreadiness_v3.6> set-executionpolicy remotesigned 
 
Execution Policy Change The execution policy helps protect you from scripts that you do not trust. 
 
Changing the execution policy might expose you to the security risks described in the about_Execution_Policies help topic at https:/go.microsoft.com/fwlink/?LinkID=135170. 
 
Do you want to change the execution policy? [Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): a

Run command.

PS C:\temp\dgreadiness_v3.6> .\DG_Readiness_Tool_v3.6.ps1 -Disable 
 
Do you want to run software from this untrusted publisher? 
 
File C:\temp\dgreadiness_v3.6\DG_Readiness_Tool_v3.6.ps1 is published by CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US and is not trusted on your system. Only run scripts from trusted publishers. 
 
[V] Never run [D] Do not run [R] Run once [A] Always run [?] Help (default is "D"): a

You will see success messages.

Disabling Hyper-V and IOMMU
 
Disabling Hyper-V and IOMMU successful
 
Please reboot the machine, for settings to be applied.

After reboot continue to install HAXM.

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Dynamic Assembly Loading (C# Reflection)

We will achieve following task with dynamic assembly loading in C#.

using System.Net.Http;
using System;
using System.Linq;

var client = new HttpClient();
client.BaseAddress = new Uri("http://api.open-notify.org/astros.json");
string result = client.GetStringAsync("").Result;

Don't add System.Net.Http dll to your reference list. It will be automatically loaded from GAC.

using System;
using System.Linq;
using System.Reflection;

//We don't have "using System.Net.Http" 

//Load System.Net.Http
string name1 = "System.Net.Http,Version=4.0.0.0," + "Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a";
Assembly a1 = Assembly.Load(name1);

//Create HttpClient instance
Type clientType = a1.GetTypes().Where(t => t.Name.Equals("HttpClient")).Single();
object client = Activator.CreateInstance(clientType);

//Set BaseAddress on client
PropertyInfo propertyBaseAddress = clientType.GetProperties().Where(p => p.Name == "BaseAddress").Single();
Uri url = new Uri("http://api.open-notify.org/astros.json");
propertyBaseAddress.SetValue(client, url);

//Test property value
var BaseAddressValue = propertyBaseAddress.GetValue(client);

//Get HttpResponseMessage Task
var methodGetStringAsync = clientType.GetMethod("GetStringAsync", new Type[] { typeof(Uri) });
var responseTask = methodGetStringAsync.Invoke(client, new string[] { null });

//Get HttpResponseMessage result from Task
var responseType = responseTask.GetType();
PropertyInfo propResponse = responseType.GetProperties().Where(p => p.Name == "Result").Single();

var responseResult = propResponse.GetValue(responseTask);  //This is the string result

Bonus: List your loaded assemblies

Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();

foreach (Assembly a in assemblies)
{
     Console.WriteLine(a.GetName());
}

Output

mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089

System.Net.Http is displayed here even not referenced in Visual Studio.

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Strong Name Signing in .NET

Using a strong name protects your assembly against manipulation.

For example your software using a class named Class1 in ClassLibrary1 namespace.

If you compile a new dll contains ClassLibrary1.Class1 then you can use this dll instead of original one.

This is very basic example but it can be applicable in real life.

To be sure that your software is using your assembly version then you can sign your project.

Microsoft description is:

When a strong-named assembly is created, it contains the simple text name of the assembly, the version number, optional culture information, a digital signature, and the public key that corresponds to the private key used for signing.

Example here shows signing process in Visual Studio. You can use also command line tool (sn.exe).

Coding

Our solution has 2 projects, executable and a class library. Main program is using ClassLibrary1.Class1

using ClassLibrary1;
using System;

namespace strongname
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("strongname loaded");

            Class1 c = new Class1();

            Console.ReadKey();
        }
    }
}

using System;

namespace ClassLibrary1
{
    public class Class1
    {
        public Class1()
        {
            Console.WriteLine("Hello from Class1");
        }
    }
}

Sign

Right click to project in VS and select Properties. In Signing tab check "Sign the assembly" and select "New" in listbox. Enter password for your private key.

This will create a pfx (Personal Information Exchange Format) file in your project folder.

Run

strongname loaded
Hello from Class1

Recompile

If you create a new project with the same namespace, class and functions then you can use the new dll with current executable.

For test change the code and recompile dll in outside of project folder.

csc.exe /t:library /out:ClassLibrary1.dll Class1.cs

Then replace the old ClassLibrary1.dll with the new file.

Result

When you try to run your executable an error will be shown because the new dll has not signed with correct key.

C:\strongname\bin\Debug\strongname.exe

Unhandled Exception: System.IO.FileLoadException: Could not load file or assembly 'ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=77d705841860f240' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
at strongname.Program.Main(String[] args)

If you completely remove signing from your projects then your manipulated dll will work.

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Asp.Net Settings for Hosting

1. Security Exception

Description: The application attempted to perform an operation not allowed by the security policy.To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.

Exception Details: System.Security.SecurityException: Request failed.

Solution:

<system.web>
   <trust level="Full" />
</system.web>

2. Publish website without roslyn

Uninstall-package Microsoft.CodeDom.Providers.DotNetCompilerPlatform "Your Web API project name"

In your publish profile settings, uncheck "Allow precompiled site to be updatable". You can find this under Settings > Precompile during publishing > configure.

Remove codedom from web.config.

  <system.codedom>
    <compilers>
      <compiler language="c#;cs;csharp" extension=".cs"
        type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
        warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701"/>
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb"
        type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
        warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\"Web\" /optionInfer+"/>
    </compilers>
  </system.codedom>

4. MapPath

  System.Web.Hosting.HostingEnvironment.MapPath("~/log");

4. Restrict file download

Create web.config file in the folder you want to prevent file download for a specific extension.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <security>
            <requestFiltering>
                <fileExtensions applyToWebDAV="false">
                     <add fileExtension=".txt" allowed="false" />
                </fileExtensions>
            </requestFiltering>
        </security>
  </system.webServer>
</configuration>

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