Searching for a more elegant way to turn a MethodInfo to a Func through Expressions

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• Decimal vs Double?

  I'm new to C#, and I want to use a trackbar for the forms opacity This is my code

  decimal trans = trackBar1.Value / 5000
  this.Opacity = trans
  

  When I try to build it, I get this error

  Cannot implicitly convert type 'decimal' to 'double

  I tried making trans a double, but then the control doesn't work. This code worked fine for me in VB.NET. Any suggestions?
• Set RestSharp content-type to application/x-www-form-urlencoded

  I don't seem to be able to change content-type to application/x-www-form-urlencoded. I found and tested similar answers but nothing seems to work. What am I doing wrong?

  request.Method = Method.POST;
          client.Authenticator = new HttpBasicAuthenticator(ABclientID, ABclientSecret);
          request.Parameters.Clear();
          request.AddHeader("Accept", "application/x-www-form-urlencoded");
          request.Parameters.Clear();
          request.AddParameter("application/x-www-form-urlencoded", $"grant_type=client_credentials&scope=account-info-setup", ParameterType.RequestBody);
          IRestResponse response = client.Execute(request);
          Response.Write(response.Content.ToString());
  

  I also tried the following code:

          request.Method = Method.POST;
          client.Authenticator = new HttpBasicAuthenticator(ABclientID, ABclientSecret);
          request.AddHeader("content-type", "application/x-www-form-urlencoded");
          request.AddParameter("application/x-www-form-urlencoded", $"grant_type=client_credentials&scope=account-info-setup", ParameterType.RequestBody);
          IRestResponse response = client.Execute(request);
          Response.Write(response.Content.ToString());
  
• WPF MVVM model SelectAll checkbox not working

  i have a checkbox .when i click selectall all the checkbox should select/deselect.I am following MVVM pattern.i have tried below code but not working.i am using the listview here for showing the data

  Xaml

      <ListView Grid.Row="1" Name="listbox" ItemsSource="{Binding Items}"   Margin="5,5,5,5" Width="Auto" >
  
          <ListView.View >
              <GridView  >
  
              <GridViewColumn Width="80"  >
                  <GridViewColumn.Header >
                      <CheckBox  x:Name="cbSelectAll" IsChecked="{Binding ModelDetails.IsChecked}"  Command="{Binding cbSelectAll_Checked}"/>
                  </GridViewColumn.Header>
  
                  <GridViewColumn.CellTemplate>
                      <DataTemplate>
                          <StackPanel Orientation="Horizontal">
                              <WrapPanel x:Name="Layout"   >
                               
                                  <CheckBox  IsChecked="{Binding ModelDetails.IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                               
                              </WrapPanel>
                          </StackPanel>
                      </DataTemplate>
                  </GridViewColumn.CellTemplate>
              </GridViewColumn>
              <GridViewColumn Header="File Name" Width="500" >
                      <GridViewColumn.CellTemplate >
                          <DataTemplate>
                              <TextBlock Name="TextBlock1" Height="30" Width="200"  Text="{Binding Name}" TextAlignment="Center"  />
                          </DataTemplate>
                      </GridViewColumn.CellTemplate>
                  </GridViewColumn>
  

  Model.cs

  class TypeModel : INotifyPropertyChanged
      {
          private bool _isSelected;
          private bool _isChecked;
          //Define an event based on delegates
          public event PropertyChangedEventHandler PropertyChanged;
          //Raise the event
          public void OnPropertyChanged(string propertyName)
          {
              if (PropertyChanged != null)
              {
                  //publishing the event in current classs
                  PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
              }
          }
  
          
  
          public bool IsChecked
          {
              get
              {
                  return this._isChecked;
              }
              set
              {
                  this._isChecked = value;
                  this.OnPropertyChanged("IsChecked");
              }
          }
         
  
          public bool IsSelected
          {
              get
              {
                  return _isSelected;
              }
              set
              {
                  _isSelected = value;
                  OnPropertyChanged("IsSelected");
              }
          }
  

  ViewModel

   private ViTypeModel _ModelDetails;
  
  
          public ViTypeModel ModelDetails
          {
              get
              {
                  return _ModelDetails;
              }
              set
              {
                  _ModelDetails = value;
              }
          }
  
  
  
  
  
  
    public void SelectAllBtnExecute(object param)//onbutton click event
      {
          if (ModelDetails.IsChecked==true)
          {
              foreach (var selectedItems in Items)
              {
                  ModelDetails.IsSelected = true;
              }
          }
          else
          {
              foreach (var selectedItems in Items)
              {
                  ModelDetails.IsSelected = false;
              }
          }
      }
  

  when i click on checkbox cbSelectAll_Checked is hitting. help me .help he to find the error.is this the right binding?

  thanks in advance.
• Cannot convert method group to non-delegate type with reflection

  I'm attempting to automatically register request handling classes with reflection.

  This is an example of manually adding a handler for execution of a certain request.

  // generic manual method of registration
  server.RegisterHandler<GetData>(base.ExecuteMessage);
  

  Here is the attempt to register with reflection. The invoke method will not accept the 'ExecuteMessage' method getting the error "Error CS0428 Cannot convert method group 'ExecuteMessage' to non-delegate type 'object'. Did you intend to invoke the method?".

  // registration with reflection
  foreach (var type in serviceTypes)
  {
      // registerHandlerMethod definition:    RegisterHandler<T>(Func<IMessage<T>, object> processMessageFn)
      // ExecuteMessage definition:           object ExecuteMessage(IMessage message)
  
      registerHandlerMethod.MakeGenericMethod(type).Invoke(server, new object[] { base.ExecuteMessage });
  }
  

  Is it possible to cast the ExecuteMessage method in any way to get this to work?
• System.Reflection Get property as an object and set another property of the property

  So, in my project, on a STL file, there are some points, when I move a point, the coordinate informations change. When a point moved, it must be marked as modified.

  And when I move the point, I have the property name of the point. From the property name, I can access to the property, it returns a Custom3DPoint.

  The Custom3DPoint class has a Status property.

  For a clearer explanation, I have a class named A which has two properties P1 and P2. And I have another class named B which has a property of type A.

  How to get the property of the object B from the propertyname P1 and set the P2 value.

  Here is what I tried :

  class A
  {
      public string P1{ get; set; }
      public string P2 { get; set; }
  
      public A()
      {
          P1 = "value1";
          P2 = "value2";
      }
  }
  
  class B
  {
      public A PropA { get; set; }
      public B()
      {
          PropA = new test.A();
  
      }
  }
  
  void Moved(B obj, string propertyName)
  {
      var prop = obj.GetType().GetProperty(propertyName);
      var statusProp = prop.GetType().GetProperty("Status"); //this line returns null because
  
      prop.GetType().GetProperties(); // doesn't return properties of A object.
  
      statusProp.SetValue(prop, "modified");
  }
  

  Is it possible using Reflection ?
• c# Altering methods in parsed code in a SyntaxTree

  I'm paring a string that contains a c# code using a SyntaxTree. What I would like to do is to alter the methods in the code:

  • Get the list of parameters passed to the method
  • Add lines of code to be executed by the method - some of them has to do with the parameters passed to the method.

  This is my code so far:

  string code = @"
  public void SayHello(string name) {
      Console.WriteLine(""Hello "" + name);
  }
  
  private string SayGoodbye() {
      Console.WriteLine(""Goodbye"");
  }
  ";
  
  SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
  
  var root = syntaxTree.GetRoot();
  var members = syntaxTree.GetCompilationUnitRoot().Members;
  
  var firstMember = members[0];
  Console.WriteLine(firstMember.ToString());
  
  Console.WriteLine(syntaxTree.ToString());
  

  firstMember contains the tree structure for the SayHello method. Using .ToString() I can get the full method string. From here what I was thinking is to take that string and parse it to get the method parameters and alter the string to add the command lines that I need. And then using reflection read that string code and execute it.

  But I was wondering, is there a more correct ".NET" way of doing such alterations parsed code?
• Using automapper expression mapping of id class to string lead to translation error in EFCore

  I use AutoMapper to translate between business logic objects (Blo) and data transfer objects (Dto). The blo-class contain an id that is a class wheras the dto contains a string for that id. To load objects out of a database an expression on blo-level is created and translated via AutoMapper to dto-level.

  The classes are:

  public class Blo
  {
      public Blo(BloId id)
      {
          this.Id = id;
      }
  
      public BloId Id { get; set; }
  }
  
  [Table("dtos")]
  public class Dto
  {
      [Column("id")]
      [Key]
      public string Id { get; set; }
  }
  
  public class BloId
  {
      private readonly string _value;
  
      public BloId(string value = null)
      {
          this._value = value ?? Guid.NewGuid().ToString();
      }
  
      public static bool operator ==(BloId left, BloId right)
      {
          if (object.ReferenceEquals(left, right))
          {
              return true;
          }
  
          if (left is null || right is null)
          {
              return false;
          }
  
          return left._value == right._value;
      }
  
      public static bool operator !=(BloId left, BloId right)
      {
          return !(left == right);
      }
  
      public override string ToString()
      {
          return this._value;
      }
  }
  

  These classes are very simplyfied and all the unneeded code is omitted due to focus on the real problem.

  The mapping I created is straight forward (using the hints of that github issue):

  cfg.CreateMap<Blo, Dto>(MemberList.None)
      .EqualityComparison((src, dst) => src.Id.ToString() == dst.Id)
      .ForMember(dst => dst.Id, opt => opt.MapFrom(src => src.Id.ToString()));
  cfg.CreateMap<Dto, Blo>(MemberList.None)
      .EqualityComparison((src, dst) => src.Id == dst.Id.ToString())
      .ForMember(dst => dst.Id, opt => opt.MapFrom(src => new BloId(src.Id)));
  

  I created a DbContext from EFCore and the following code to find an item:

  var mapper = CreateMapper();
  await using (var ctx = new MyContext())
  {
      var idToFind = new BloId("Container-Id 000");
  
      Expression<Func<Blo, bool>> bloFilter = c => c.Id == idToFind;
      var dtoFilter = mapper.MapExpression<Expression<Func<Dto, bool>>>(bloFilter);
      var found = await ctx.Dtos.FirstOrDefaultAsync(dtoFilter);
  }
  

  This works as expected if I use an in-memory database. But if I switch to e.g. a SQLite database the following exception occurs:

  The LINQ expression 'DbSet<Dto> .Where(d => new BloId(d.Id) == Container-Id 000)' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

  And the reason is absolutally clear: The bloFilter is

  c => (c.Id == value(AutoMapperVsEfCore.Program+<>c__DisplayClass0_0).idToFind)
  

  that is translated to the dtoFilter

  c => (new BloId(c.Id) == Container-Id 000)
  

  That is the problem! There is no way to create an instance of BloId in SQL.

  The expected dto-filter might be something like: c => (c.Id == "Container-Id 000")

  But I've absolutally no idea how I have to configure AutoMapper to translate my specified blo-filter to a working dto-filter.

  How do I create such a filter?

  For completeness the used DbContext is:

  public class MyContext : DbContext
  {
      public const string DatabasePath = @"D:\Temp\testing.db";
  
      public DbSet<Dto> Dtos { get; set; }
  
      protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
      {
          //optionsBuilder.UseInMemoryDatabase("testing");
          optionsBuilder.UseSqlite(new SqliteConnectionStringBuilder { DataSource = DatabasePath }.ToString());
  
          base.OnConfiguring(optionsBuilder);
      }
  }
  
• Generic IsNullOrEmpty extension for EntityFramework objects

  TLDR: I would like to create an extension method with the following signature and I am struggling to work out how to fill the method in correctly.

  public static Expression<Func<TSource, bool>> IsNullOrEmpty<TSource>(this TSource source, Expression<Func<TSource, string>> member) 
  {
      //What goes here?
      //I thought something like this might work but I understand why it doesn't.... i.e. Can't infer what method does...
      //return o => member(o) == null || member(o).Trim() == "";
      //return o => string.IsNullOrEmpty(member(o));
  }
  

  Long version:

  I have a bunch of code that looks like this throughout my project

  using (var dsContext = this._dsFactory.Create())
  {
      var r = await dsContext.Stocks.FirstOrDefaultAsync(o => o.MyId1.IsNotNullOrEmpty() && o.MyId2.IsNotNullOrEmpty());
  }
  
  public static bool IsNullOrEmpty(this string value)
  {
      return string.IsNullOrEmpty(value); 
  }
  
  public static bool IsNotNullOrEmpty(this string value)
  { 
      return !StringExtensions.IsNullOrEmpty(value);
  }
  

  The above code worked successfully until after changing the behaviour of my DBContext (where previously I would only deal with fully materialized collections in-memory I am now working with IQueryable directly and hoping to execute SQL queries to filter my data) this started failing with 'LINQ to Entities does not recognize the method 'Boolean IsNotNullOrEmpty(System.String)' method, and this method cannot be translated into a store expression.'.

  The cause of this is fairly self explanatory however I can successfully execute the following code.

  var r = await dsContext.Stocks.FirstOrDefaultAsync(o => !string.IsNullOrEmpty(o.MyId1) &&  !string.IsNullOrEmpty(o.MyId2));
  

  which means that provided that EntityFramework is provided with the correctly structured expression building an extension method for this should be possible.

  Can anyone please help?
• Unexplainable result of an expression

  I'm currently working on a project where I've got stuck due to "out of range", "memory access violation" and other similar issues. Having spent much time trying to figure out where the problems come from, I came to a trivial piece of code like this:

  #include <iostream>
  
  #define RANDOM(min, max) min + RAND_MAX / ((RAND_MAX - 1) / (max - min))
  
  int main() {
      std::cout << RANDOM(0, 500) << std::endl;
  }
  

  One compiler clang says 500, that's what I expect it to say. Another one (gcc I guess, I use VS2017) says 504. Later I found out that the value of RAND_MAX for the both is different and if I specify the same value for clang, it also says 504. Here the value of RAND_MAX is 32767.

  I went to my Python shell to calculate the expression manually. So I typed in

  0 + 32767 / ((32767 - 1) / (500 - 0))
  

  and got the result 500.015259720442. This is no way 504. How is it possible?