Calling LinqPad 7 from Visual Studio C# Project

Question

I am trying to call LinqPad query from C#. Unfortunately, the code below does not work; the result is null as if nothing got returned by the script. I don't see any example of how to do this online. Any direction would be appreciated.

This is the LinqPad code for the query. It is saved as a C# Statement:

string Main(string message)
{
    "testing".Dump();
    return message.ToUpper();
}

This is the code in C# code in a Visual Studio Project Console Application that attempts to call the query:

using System;

using LINQPad;


namespace ConsoleAppLinqPad
{
    internal class Program
    {
        static void Main(string[] args)
        {
            string pathToQuery = @"C:\Users\synct\OneDrive\Documents\LINQPad Queries\";
            string script = "samplequery.linq";
            var wholePath = pathToQuery + script;

            using (var query = Util.Compile(wholePath))
            {
                var results = query.Run(QueryResultFormat.Text, "hello world").ReturnValueAsync.GetAwaiter();

                while (!results.IsCompleted)
                    ;


                var result = results.GetResult();
                Console.WriteLine(result.Dump());  // prints "HELLO WORLD?"
                
            }

            Console.ReadKey();
        }
    }
}

Answer 1

There is a LPRun7-x64.exe shipped with LinqPad (ARM64 and x86 versions are available as well) which allows to run LinqPad from a console. But you can also run it from a process.

With the example below you could run your samplequery.linq like:

string pathToQuery = @"C:\Users\synct\OneDrive\Documents\LINQPad Queries\";
string script = "samplequery.linq";
RunLpQuery(@$"{pathToQuery}{script}");

Example:

void Main()
{
    RunLpQuery(@$"{AppPath}\Hello.linq");
}

public string AppPath =>
#if LINQPAD
    System.IO.Path.GetDirectoryName(Util.CurrentQueryPath);
#else
    System.IO.Path.GetDirectoryName(Assembly.GetAssembly(this.GetType()).Location);
#endif

// Linqpad 4+5: "LPRun.exe"
// LinqPad 6:   "LPRun6.exe"
// Linqpad 7:   "LPRun7-x64.exe"  
public const string LpRunName = "LPRun7-x64.exe";

object RunLpQuery(string query)
#if LINQPAD
    => Util.Run(query, QueryResultFormat.Html).Dump();
#else
    => StartProcess(@$"{Util.LINQPadFolder}\{LpRunName}", AppPath, query);
#endif

bool StartProcess(string fileName, string workingDir, string arguments,
                  bool hidden = false)
{
    var p = new Process();
    var args = p.StartInfo;
    if (hidden)
    {
        args.CreateNoWindow = true; args.UseShellExecute = false; // runs hidden
    }
    args.FileName = fileName;
    args.WorkingDirectory = workingDir;
    args.Arguments = arguments;
    var result = p.Start();
    p.WaitForExit();
    return result;
}

Hello.linq:

void Main()
{
    for (int i = 0; i < 5; i++)
    {
        "Hello World!".Dump(); Thread.Sleep(500);
    }   
}

Note that the example uses conditional compilation: Through #if LINQPAD statements it can run directly inside of LinqPad itself, showing the output of the called Hello example in the result windows, or outside in a Visual Studio project.

---

Details about the parameters for lprun can be found here. And if you just want to use LinqPad's extensions in the context of your VS project, then have a look there.