Failed to create Constructor node from .NET Core Library

[soundslikesound]

Hello, I have troubles creating Constructor Node from .NET core library. 
When I select object (green) in library I do not see any available constructors (red). I am able to click "OK" button, but Constructor node stays empty. Do you know what causes this? 

Usually when object do not have public constructor, it looks like this, and OK button is disabled. See picture below.

[zou]

Not all item in the .Net lib can create Constructor.

For static items, you can use properties nodes/invoke node directly without a constructor.

[Andrey_Dmitriev]

Just quickly checked this and it works

Source:

namespace netCore;

	public class MathClass    
    {    
        public MathClass() { }    
    
        public double Calculate(double num1, double num2, string op)    
        {    
            double result = 0;    
            switch (op)    
            {    
                case "Add":    
                    result = num1 + num2;    
                    break;    
                case "Sub":    
                    result = num1 - num2;    
                    break;    
                case "Mul":    
                    result = num1 * num2;      
                    break;    
                case "Div":    
                    result = (double)num1 / num2;                      
                    break;    
                default:           
                    break;    
            }    
            return result;    
        }    
    }

Call:

Unfortunately I haven't 32-bit LabVIEW in my hands, may be 64/32 bitness is your problem?

Try to build your library as

dotnet build --runtime win-x86

[soundslikesound]

Hello zou, I am aware that, I am already using some static methods from .NET Framework library. However I am confused, how do I choose  property/invoke node for .NET Core or .NET Framework. When select DLL (which is readable for .NET Core Constructor Node) for Property Node I get error below. 

For Constructor node there is an option to choose from .NET Framework/.NET Core, I don't see that for Invoke/Property node.

Can you help?

[Andrey_Dmitriev]

---

@soundslikesound  a écrit :

For Constructor node there is an option to choose from .NET Framework/.NET Core, I don't see that for Invoke/Property node.

---

You don't need this, because the option .NET Framework/.NET Core is only for the constructor, and from this point there are no any differences in term of called methods.

Another reason is why you have such trouble is dependencies. If your .net "SQL" assembly dependent on other DLL, and this dependent DLL (could be related to SQL in your case) cannot be located properly when called from LabVIEW, then you will get an error. Try to prepare a very simple .net core (or take it from examples <LabVIEW>\examples\Connectivity\Dot NET Core") and check if it works and how, then add additional complexity to your code.

[soundslikesound]

Hi Andrey, thank you for your answers. I rebuild my company DLLs to 32bit, otherwise I got error 'Error occured trying loading assembly', so that should be an issue.

I also created simple .NET Core library with method returning true/false, Constructor node works just fine. 

I will probably have to create new test project for my DLL and slowly add additional complexity to my code, like you already wrote.

namespace LibraryTest
{
    public static class Class1
    {
        public static bool Method1()
        {
            return true;
        }
    }
}

Still I have troubles to work with invoke/property nodes. I have written this simple library (source above) with static method. I am able to load it with Constructor node, I am able to see Class1 and upon selecting it gives me error 'This class contains no public constructors', which is OK. Works as it should be.

However when I try to create Property Node and load DLL I got error 'Error trying to load assembly'. 

Same library can be loaded through .NET Core Constructor, can not be loaded through Propery Node. Am I missing something? 

[Andrey_Dmitriev]

---

@soundslikesound  a écrit :

Am I missing something? 

---

Yes, just slightly modify your code like this:

namespace LibraryTest
{
	public class Class1
	{
		public Class1() { }
		public bool Method1()
		{
			return true;
		}
	}
}

and you will get it:

In my understanding you must have a constructor for the LabVIEW node and in general the best practice is to avoid public static... You creating instance in LabVIEW and static is actually not a member of instance, but member of type. Or did you trying to implement kind of singleton pattern?

[rolfk]

Also, .Net Core support in LabVIEW is preliminary and not complete. It has been stated that way by NI developers. They did debate if they should release what they have or wait another release cycle until they have more working. Eventually they decided to release what is present and use the feedback to prioritize the work to be done next. It will take more than one additional release before .Net Core is fully working as intended (and no that won't mean it will support every possible feature from .Net).