DinkToPdf Net Core not able to load DLL files

5
votes

I am trying to generate PDFs from HTML SQL server database using DinkToPdf library.

In the startup file I have added:

var context = new CustomAssemblyLoadContext();
context.LoadUnmanagedLibrary(Path.Combine(Directory.GetCurrentDirectory(), "libwkhtmltox.dll"));

The line gives me this error on launching the web app:

DllNotFoundException: Unable to load DLL 'C:\Program Files\IIS Express\libwkhtmltox.dll' or one of its dependencies: The specified module could not be found. (Exception from HRESULT: 0x8007007E)

System.Runtime.Loader.AssemblyLoadContext.InternalLoadUnmanagedDllFromPath(string unmanagedDllPath)

DllNotFoundException: Unable to load DLL 'C:\Program Files\IIS Express\libwkhtmltox.dll' or one of its dependencies: The specified module could not be found. (Exception from HRESULT: 0x8007007E)

4
c#.net-corewkhtmltopdfhtml-to-pdfdinktopdf
Is it just okay if you import dinktopdf using nuget? insead of loading it directly as unamange? – keysl
Hello, I have imported. I have installed it well. In its description of use, I must import the dll files from the run. But this method Directory.GetCurrentDirectory() seems to not bet working on Asp.Net Core 3.0 – Joseph Wambura
Asp.Net Core Directory.GetCurrentDirectory() I think is the culprit here. It is returning C:\Program Files\IIS Express\ as the default folder for the project – Joseph Wambura
Farzaneh Talebi posted an Answer saying "I had same problem and this tutorial helped me: medium.com/volosoft/…" – Scratte

4 Answers

10
votes

Just in case anyone else is having the same issue I was able to solve it by installing Microsoft Visual C++ 2015 Redistributable.

8
votes

It is mentioned in library's git repo that you should download binaries and include them in your source code:

Copy native library to root folder of your project. From there .NET Core loads native library when native method is called with P/Invoke. You can find latest version of native library here. Select appropriate library for your OS and platform (64 or 32 bit).

What was breaking things was that I was going to that url and right click on each file and select save link as(chrome). This leads to a broken file being downloaded: enter image description here

DON'T DO THAT you have to open each file within github and then use that Download button. The healthy file is much bigger than what you would get if you go the wrong way!

enter image description here

ridiculous but the problem may be caused by this ...

1
votes

I found some work-arounds. They are not perfect but worth a try, and they did do help and I was able to generate PDFs from SQl Server. I put the .dll files in the following folder and it worked.

C:\Program Files\IIS Express

and the loaded the .dll files with

Path.Combine(Directory.GetCurrentDirectory(), "libwkhtmltox.dll");

The other way I went for the whole Path

context.LoadUnmanagedLibrary(Path.GetFullPath(@"C:\Users\User\source\repos\WebSolution\WebApp\libwkhtmltox.dll"));

Both of them worked. However, I urge Net Core developers to work on the GetCurrentDir very well. Or a Method to load from the Project or Solution Folder

Path.Combine(Directory.GetCurrentDirectory(), "libwkhtmltox.dll");
1
votes

On Asp.Net Core application I use it like this to get the current directory on runtime

#if DEBUG
            //windows
            string filePath = $@"{Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)}\libwkhtmltox.dll";
#else
            //linux
            string filePath = @$"{(($@"{Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)}/libwkhtmltox.so").Replace(@"\", @"/"))}";
#endif
            CustomAssemblyLoadContext context = new CustomAssemblyLoadContext();
            context.LoadUnmanagedLibrary(filePath);
            serviceCollection.AddSingleton(typeof(IConverter), new SynchronizedConverter(new PdfTools()));
#endregion