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Add HostedCommandHandler helper class #1356

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Add HostedCommandHandler helper class #1356

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0ebcd51
Add HostedCommandHandler helper class
fredrikhr Jul 19, 2021
50b949a
Replace UseCommandHandler with HostedCommandHandler and IOptions
fredrikhr Jul 19, 2021
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127 changes: 92 additions & 35 deletions src/System.CommandLine.Hosting.Tests/HostingHandlerTest.cs
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Original file line number Diff line number Diff line change
@@ -1,61 +1,67 @@
using System.CommandLine.Binding;
using System.CommandLine.Builder;
using System.CommandLine.Invocation;
using System.CommandLine.IO;
using System.CommandLine.Parsing;
using System.Linq;
using System.Threading.Tasks;

using FluentAssertions;

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;

using Xunit;


namespace System.CommandLine.Hosting.Tests
{
public static class HostingHandlerTest
{

[Fact]
public static async Task Constructor_Injection_Injects_Service()
{
var service = new MyService();

var parser = new CommandLineBuilder(
new MyCommand()
new MyCommand { Handler = HostedCommandHandler.CreateFromHost<MyCommand.MyHandler>() }
)
.UseHost((builder) => {
builder.ConfigureServices(services =>
.UseHost((builder) =>
{
builder.ConfigureServices((context, services) =>
{
services.AddTransient<MyCommand.MyHandler>();
services.AddOptions<MyCommand.MyOptions>()
.BindCommandLine();
services.AddTransient(x => service);
})
.UseCommandHandler<MyCommand, MyCommand.MyHandler>();
});
})
.Build();

var result = await parser.InvokeAsync(new string[] { "--int-option", "54"});
var result = await parser.InvokeAsync(new string[] { "--int-option", "54" });

service.Value.Should().Be(54);
result.Should().Be(54);
}

[Fact]
public static async Task Parameter_is_available_in_property()
{
var parser = new CommandLineBuilder(new MyCommand())
var parser = new CommandLineBuilder(
new MyCommand { Handler = HostedCommandHandler.CreateFromHost<MyCommand.MyHandler>() }
)
.UseHost(host =>
{
host.ConfigureServices(services =>
{
services.AddTransient<MyCommand.MyHandler>();
services.AddOptions<MyCommand.MyOptions>()
.BindCommandLine();
services.AddTransient<MyService>();
})
.UseCommandHandler<MyCommand, MyCommand.MyHandler>();
});
})
.Build();

var result = await parser.InvokeAsync(new string[] { "--int-option", "54"});
var result = await parser.InvokeAsync(new string[] { "--int-option", "54" });

result.Should().Be(54);
}
Expand All @@ -65,20 +71,30 @@ public static async Task Can_have_diferent_handlers_based_on_command()
{
var root = new RootCommand();

root.AddCommand(new MyCommand());
root.AddCommand(new MyOtherCommand());
root.AddCommand(new MyCommand
{
Handler = HostedCommandHandler.CreateFromHost<MyCommand.MyHandler>()
});
root.AddCommand(new MyOtherCommand
{
Handler = HostedCommandHandler.CreateFromHost<MyOtherCommand.MyHandler>()
});
var parser = new CommandLineBuilder(root)
.UseHost(host =>
{
host.ConfigureServices(services =>
{
services.AddTransient<MyCommand.MyHandler>();
services.AddOptions<MyCommand.MyOptions>()
.BindCommandLine();
services.AddTransient<MyOtherCommand.MyHandler>();
services.AddOptions<MyOtherCommand.MyOptions>()
.BindCommandLine();
services.AddTransient<MyService>(_ => new MyService()
{
Action = () => 100
});
})
.UseCommandHandler<MyCommand, MyCommand.MyHandler>()
.UseCommandHandler<MyOtherCommand, MyOtherCommand.MyHandler>();
});
})
.Build();

Expand All @@ -96,15 +112,20 @@ public static async Task Can_bind_to_arguments_via_injection()
{
var service = new MyService();
var cmd = new RootCommand();
cmd.AddCommand(new MyOtherCommand());
cmd.AddCommand(new MyOtherCommand
{
Handler = HostedCommandHandler.CreateFromHost<MyOtherCommand.MyHandler>()
});
var parser = new CommandLineBuilder(cmd)
.UseHost(host =>
{
host.ConfigureServices(services =>
{
services.AddTransient<MyOtherCommand.MyHandler>();
services.AddOptions<MyOtherCommand.MyOptions>()
.BindCommandLine();
services.AddSingleton<MyService>(service);
})
.UseCommandHandler<MyOtherCommand, MyOtherCommand.MyHandler>();
});
})
.Build();

Expand All @@ -113,29 +134,55 @@ public static async Task Can_bind_to_arguments_via_injection()
service.StringValue.Should().Be("TEST");
}

[Fact]
public static void Throws_When_Injected_HandlerType_is_not_ICommandHandler()
{
new object().Invoking(_ =>
{
var handlerWrapper = HostedCommandHandler.CreateFromHost(
typeof(MyNonCommandHandler));
}).Should().ThrowExactly<ArgumentException>(
because: $"{typeof(MyNonCommandHandler)} does not implement {typeof(ICommandHandler)}"
);
}

[Fact]
public static void Throws_When_Injected_HandlerType_is_null()
{
new object().Invoking(_ =>
{
var handlerWrapper = HostedCommandHandler.CreateFromHost(null);
}).Should().ThrowExactly<ArgumentNullException>();
}

public class MyCommand : Command
{
public MyCommand() : base(name: "mycommand")
{
AddOption(new Option<int>("--int-option")); // or nameof(Handler.IntOption).ToKebabCase() if you don't like the string literal
}

public class MyOptions
{
public int IntOption { get; set; } // bound from option
public IConsole Console { get; set; } // bound from DI
}

public class MyHandler : ICommandHandler
{
private readonly MyService service;
private readonly MyOptions options;

public MyHandler(MyService service)
public MyHandler(MyService service, IOptions<MyOptions> options)
{
this.service = service;
this.options = options.Value;
}

public int IntOption { get; set; } // bound from option
public IConsole Console { get; set; } // bound from DI

public Task<int> InvokeAsync(InvocationContext context)
{
service.Value = IntOption;
return Task.FromResult(IntOption);
service.Value = options.IntOption;
return Task.FromResult(options.IntOption);
}
}
}
Expand All @@ -148,24 +195,29 @@ public MyOtherCommand() : base(name: "myothercommand")
AddArgument(new Argument<string>("One"));
}

public class MyOptions
{
public int IntOption { get; set; } // bound from option
public IConsole Console { get; set; } // bound from DI
public string One { get; set; }
}

public class MyHandler : ICommandHandler
{
private readonly MyService service;
private readonly MyOptions options;

public MyHandler(MyService service)
public MyHandler(MyService service, IOptions<MyOptions> options)
{
this.service = service;
this.options = options.Value;
}

public int IntOption { get; set; } // bound from option
public IConsole Console { get; set; } // bound from DI

public string One { get; set; }

public Task<int> InvokeAsync(InvocationContext context)
{
service.Value = IntOption;
service.StringValue = One;
service.Value = options.IntOption;
service.StringValue = options.One;
return Task.FromResult(service.Action?.Invoke() ?? 0);
}
}
Expand All @@ -179,5 +231,10 @@ public class MyService

public string StringValue { get; set; }
}

public class MyNonCommandHandler
{
public static int DoSomething() => 0;
}
}
}
68 changes: 68 additions & 0 deletions src/System.CommandLine.Hosting/HostedCommandHandler.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,68 @@
using System.CommandLine.Hosting;
using System.Threading.Tasks;

using Microsoft.Extensions.DependencyInjection;

namespace System.CommandLine.Invocation
{
/// <summary>
/// Proviveds helper methods to initialize a command handler that uses
/// Dependency Injection from the .NET Generic Host to materialize
/// the handler.
/// </summary>
/// <seealso cref="CommandHandler"/>
public static class HostedCommandHandler
{
private class HostedCommandHandlerWrapper<THostedCommandHandler> : ICommandHandler
where THostedCommandHandler : ICommandHandler
{
public Task<int> InvokeAsync(InvocationContext context)
{
var host = context.GetHost();
var handler = host.Services.GetRequiredService<THostedCommandHandler>();
return handler.InvokeAsync(context);
}
}

/// <summary>
/// Creates an <see cref="ICommandHandler"/> instance that when invoked
/// will forward the <see cref="InvocationContext"/> to an instance of
/// <paramref name="commandHandlerType"/> obtained from the DI-container
/// of the .NET Generic Host used in the invocation pipeline.
/// </summary>
/// <param name="commandHandlerType">A command handler service type implementing <see cref="ICommandHandler"/> that has been registered with the .NET Generic Host DI-container.</param>
/// <returns>A wrapper object that implements the <see cref="ICommandHandler"/> interface by forwarding the call to <see cref="ICommandHandler.InvokeAsync(InvocationContext)"/> to the implementation of <typeparamref name="TCommandHandler"/>.</returns>
/// <exception cref="ArgumentNullException"><paramref name="commandHandlerType"/> is <see langword="null"/>.</exception>
/// <exception cref="ArgumentException"><paramref name="commandHandlerType"/> does not implement the <see cref="ICommandHandler"/> interface type.</exception>
public static ICommandHandler CreateFromHost(Type commandHandlerType)
{
_ = commandHandlerType ?? throw new ArgumentNullException(nameof(commandHandlerType));
Type wrapperHandlerType;
try
{
wrapperHandlerType = typeof(HostedCommandHandlerWrapper<>)
.MakeGenericType(commandHandlerType);
}
catch (ArgumentException argExcept)
{
throw new ArgumentException(
paramName: nameof(commandHandlerType),
message: $"{commandHandlerType} does not implement the {typeof(ICommandHandler)} interface.",
innerException: argExcept);
}
return (ICommandHandler)Activator.CreateInstance(wrapperHandlerType);
}

/// <summary>
/// Creates an <see cref="ICommandHandler"/> instance that when invoked
/// will forward the <see cref="InvocationContext"/> to an instance of
/// <typeparamref name="TCommandHandler"/> obtained from the DI-container
/// of the .NET Generic Host used in the invocation pipeline.
/// </summary>
/// <typeparam name="TCommandHandler">A command handler service type that has been registered with the .NET Generic Host DI-container.</typeparam>
/// <returns>A wrapper object that implements the <see cref="ICommandHandler"/> interface by forwarding the call to <see cref="ICommandHandler.InvokeAsync(InvocationContext)"/> to the implementation of <typeparamref name="TCommandHandler"/>.</returns>
public static ICommandHandler CreateFromHost<TCommandHandler>()
where TCommandHandler : ICommandHandler =>
new HostedCommandHandlerWrapper<TCommandHandler>();
}
}
35 changes: 0 additions & 35 deletions src/System.CommandLine.Hosting/HostingExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -82,41 +82,6 @@ public static OptionsBuilder<TOptions> BindCommandLine<TOptions>(
});
}

public static IHostBuilder UseCommandHandler<TCommand, THandler>(this IHostBuilder builder)
where TCommand : Command
where THandler : ICommandHandler
{
return builder.UseCommandHandler(typeof(TCommand), typeof(THandler));
}

public static IHostBuilder UseCommandHandler(this IHostBuilder builder, Type commandType, Type handlerType)
{
if (!typeof(Command).IsAssignableFrom(commandType))
{
throw new ArgumentException($"{nameof(commandType)} must be a type of {nameof(Command)}", nameof(handlerType));
}

if (!typeof(ICommandHandler).IsAssignableFrom(handlerType))
{
throw new ArgumentException($"{nameof(handlerType)} must implement {nameof(ICommandHandler)}", nameof(handlerType));
}

if (builder.Properties[typeof(InvocationContext)] is InvocationContext invocation
&& invocation.ParseResult.CommandResult.Command is Command command
&& command.GetType() == commandType)
{
invocation.BindingContext.AddService(handlerType, c => c.GetService<IHost>().Services.GetService(handlerType));
builder.ConfigureServices(services =>
{
services.AddTransient(handlerType);
});

command.Handler = CommandHandler.Create(handlerType.GetMethod(nameof(ICommandHandler.InvokeAsync)));
}

return builder;
}

public static InvocationContext GetInvocationContext(this IHostBuilder hostBuilder)
{
_ = hostBuilder ?? throw new ArgumentNullException(nameof(hostBuilder));
Expand Down