C# – Passing array to custom MSBuild task

cmsbuildmsbuild-task

I thought this would be quite simple but then realised that I couldnt find any information on it anywhere.

I have a custom task like so:

public class MyCustomTask : Task
{
    [Required]
    public string[] SomeStrings {get;set;}

    public override bool Execute()
    {
        // Do something with strings...
    }
}

The matching MSBuild stuff is basically like so:

<UsingTask TaskName="MyCustomTask" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildBinPath)\Microsoft.Build.Tasks.v4.0.dll">
    <ParameterGroup>
      <SomeStrings ParameterType="System.String[]" Required="true" />
    </ParameterGroup>
    <Task>
    ... 
    </Task>
</UsingTask>

<Target Name="DoSomething">
    <MyCustomTask SomeStrings="????" />
</Target>

Dont have any idea of what to put in the SomeStrings parameter, thought maybe it would understand if I did "xxx,xxx,xxx" so can anyone shed any light on this. The basic scenario is alot like tokenizing so I require a list of strings then some comparison strings so I need to pass in 2 lists/arrays, but just stumped.

Best Answer

@BrianKretzler is exactly dead on in using ITaskItem, since it's what MSBuild uses when you declare an <ItemGroup>.

I just wanted to flush out the answer with a full working example, since I found this post while I was trying to accomplish the same thing and it helped me out. (It's very hard to search for these problems, because the keywords are used in different contexts, so hopefully this will help someone else).

<UsingTask TaskName="MyCustomTask" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">
    <ParameterGroup>
        <SomeStrings ParameterType="Microsoft.Build.Framework.ITaskItem[]" Required="true" />
    </ParameterGroup>
    <Task>
        <Code Type="Class" Language="cs"><![CDATA[
            using System;
            using Microsoft.Build.Framework;
            using Microsoft.Build.Utilities;

            public class MyCustomTask : Task
            {  
                public ITaskItem[] SomeStrings { get; set; }

                public override bool Execute()
                {
                    foreach (var item in SomeStrings)
                    {
                        Log.LogMessage(MessageImportance.High, 
                                       "Got item {0}",
                                       item.ItemSpec);
                        Log.LogMessage(" -> {0} -> {1}", 
                                       item.GetMetadata("Comparison"),
                                       item.GetMetadata("MoreDetail"));
                    }
                    return true;
                }
            }
        ]]></Code>
    </Task>
</UsingTask>

Now you can call this task with:

<Target Name="DoSomething">
    <ItemGroup>
       <SomeStrings Include="first string">
          <Comparison>first</Comparison>
       </SomeStrings>
       <SomeStrings Include="second string">
          <Comparison>2nd</Comparison>
          <MoreDetail>this is optional</MoreDetail>
       </SomeStrings>
    </ItemGroup>
    <MyCustomTask SomeStrings="@(SomeStrings)" />
</Target>

and the output is:

Microsoft (R) Build Engine Version 4.0.30319.1
[Microsoft .NET Framework, Version 4.0.30319.269]
Copyright (C) Microsoft Corporation 2007. All rights reserved.

Build started 2012-10-19 5:41:22 PM.
Got first string
 -> first -> 
Got second string
 -> 2nd -> this is optional

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.12

You can of course also use something like <ItemGroup><SomeStrings Include="**\*.txt" /></ItemGroup> and you'll get the list of filenames that are matched, and of course you can use GetMetadata() to access the well-known file metadata

Related Solutions

C# – Creating a byte array from a stream

It really depends on whether or not you can trust s.Length. For many streams, you just don't know how much data there will be. In such cases - and before .NET 4 - I'd use code like this:

public static byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[16*1024];
    using (MemoryStream ms = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}

With .NET 4 and above, I'd use Stream.CopyTo, which is basically equivalent to the loop in my code - create the MemoryStream, call stream.CopyTo(ms) and then return ms.ToArray(). Job done.

I should perhaps explain why my answer is longer than the others. Stream.Read doesn't guarantee that it will read everything it's asked for. If you're reading from a network stream, for example, it may read one packet's worth and then return, even if there will be more data soon. BinaryReader.Read will keep going until the end of the stream or your specified size, but you still have to know the size to start with.

The above method will keep reading (and copying into a MemoryStream) until it runs out of data. It then asks the MemoryStream to return a copy of the data in an array. If you know the size to start with - or think you know the size, without being sure - you can construct the MemoryStream to be that size to start with. Likewise you can put a check at the end, and if the length of the stream is the same size as the buffer (returned by MemoryStream.GetBuffer) then you can just return the buffer. So the above code isn't quite optimised, but will at least be correct. It doesn't assume any responsibility for closing the stream - the caller should do that.

See this article for more info (and an alternative implementation).

C# – How to convert a byte array to a hexadecimal string, and vice versa

You can use Convert.ToHexString starting with .NET 5.
There's also a method for the reverse operation: Convert.FromHexString.

For older versions of .NET you can either use:

public static string ByteArrayToString(byte[] ba)
{
  StringBuilder hex = new StringBuilder(ba.Length * 2);
  foreach (byte b in ba)
    hex.AppendFormat("{0:x2}", b);
  return hex.ToString();
}

or:

public static string ByteArrayToString(byte[] ba)
{
  return BitConverter.ToString(ba).Replace("-","");
}

There are even more variants of doing it, for example here.

The reverse conversion would go like this:

public static byte[] StringToByteArray(String hex)
{
  int NumberChars = hex.Length;
  byte[] bytes = new byte[NumberChars / 2];
  for (int i = 0; i < NumberChars; i += 2)
    bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
  return bytes;
}

Using Substring is the best option in combination with Convert.ToByte. See this answer for more information. If you need better performance, you must avoid Convert.ToByte before you can drop SubString.

Best Answer

Related Solutions

C# – Creating a byte array from a stream

C# – How to convert a byte array to a hexadecimal string, and vice versa

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