如何使用libgit2sharp（git cat-file）获取文件的头版

Question

I have a git repository with uncommited/unstaged changes. I'd like to load the currently committed version of a file into a string in C# and another string with the current version of the file. (The latter can be accomplished without git)

Can this be done without changing the files of the repository (ie stashing) and without checking out another version of the repo to a temporary path?

The same problem would be solved by getting the "before" and "after" version of a diff.

Answer 1

You can get content for an individual file from a GitObject Blob commit's indexer.

Note: The following assumes you are dealing with a non-binary UTF8 file, adjust to your needs.

git cat-file equals:

var blob = repo.Head.Tip[{FilePathToContentFrom}].Target as Blob;
using (var content = new StreamReader(blob.GetContentStream(), Encoding.UTF8))
{
   commitContent = content.ReadToEnd();
}

The output from my example below showing the patch file of a modified file, README.md, the content from the last commit (Head.tip in this case) and the current, working directory, file's content.

~~~~ Patch file ~~~~
diff --git a/README.md b/README.md
index aa2c023..a778f15 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ The CI builds are generously hosted and run on [Travis][travis]

 ## What is PlayScript?

-[PlayScript](https://github.com/PlayScriptRedux/playscript) is an open source Adobe ActionScript compatible compiler and Flash compatible runtime that runs in the Mono .NET environment, targeting mobile devices through the Xamarin platform. With a combination of Adobe FlashBuilder for Web and Xamarin Studio for mobile complex large scale cross-mobile-web projects can be developed with full IDE, source debugging and intellisense support on all platforms, with access to the full native mobile API's on the mobile platform.
+STACKOVERFLOW [PlayScript](https://github.com/PlayScriptRedux/playscript) is an open source Adobe ActionScript compatible compiler and Flash compatible runtime that runs in the Mono .NET environment, targeting mobile devices through the Xamarin platform. With a combination of Adobe FlashBuilder for Web and Xamarin Studio for mobile complex large scale cross-mobile-web projects can be developed with full IDE, source debugging and intellisense support on all platforms, with access to the full native mobile API's on the mobile platform.

 In addition to accurate ActionScript language support, the PlayScript compiler also supports a new language - PlayScript - which is derived from both C# and ActionScript.  This new language supports all of the features of C#, including generics, properties, events, value types, operator overloading, async programming, linq, while at the same time being upwards compatible with ActionScript.  The PlayScript language can be used to target both desktop and mobile (via Xamarin), and existing Flash/ActionScript code can easily be converted to PlayScript code by simply renaming files from .as to .play, and fixing a few issues related to the stricter syntax and semantics of the PlayScript language.


~~~~ Original file ~~~~
## What is PlayScript?

[PlayScript](https://github.com/PlayScriptRedux/playscript) is an open source Adobe ActionScript compatible compiler and Flash compatible runtime that runs in the Mono .NET environment, targeting mobile devices through the Xamarin platform. With a combination of Adobe FlashBuilder for Web and Xamarin Studio for mobile complex large scale cross-mobile-web projects can be developed with full IDE, source debugging and intellisense support on all platforms, with access to the full native mobile API's on the mobile platform.

---{250 lines removed}---
 [travis]: https://travis-ci.org/

~~~~ Current file ~~~~
## What is PlayScript?

STACKOVERFLOW [PlayScript](https://github.com/PlayScriptRedux/playscript) is an open source Adobe ActionScript compatible compiler and Flash compatible runtime that runs in the Mono .NET environment, targeting mobile devices through the Xamarin platform. With a combination of Adobe FlashBuilder for Web and Xamarin Studio for mobile complex large scale cross-mobile-web projects can be developed with full IDE, source debugging and intellisense support on all platforms, with access to the full native mobile API's on the mobile platform.

---{250 lines removed}---
 [travis]: https://travis-ci.org/

Cut/Paste C# Console app (just change the location of your repo to test it):

using System;
using System.IO;
using System.Text;
using System.Collections.Generic;
using LibGit2Sharp;

namespace libgitblob
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            var repo = new Repository ("/Users/administrator/code/playscript/playscriptredux/playscript");
            foreach (var item in repo.RetrieveStatus()) {
                if (item.State == FileStatus.Modified) {
                    var patch = repo.Diff.Compare<Patch> (new List<string>() { item.FilePath });
                    var blob = repo.Head.Tip[item.FilePath].Target as Blob;
                    string commitContent;
                    using (var content = new StreamReader(blob.GetContentStream(), Encoding.UTF8))
                    {
                        commitContent = content.ReadToEnd();
                    }
                    string workingContent;
                    using (var content = new StreamReader(repo.Info.WorkingDirectory + Path.DirectorySeparatorChar + item.FilePath, Encoding.UTF8))
                    {
                        workingContent = content.ReadToEnd();
                    }
                    Console.WriteLine ("~~~~ Patch file ~~~~");
                    Console.WriteLine (patch.Content);
                    Console.WriteLine ("\n\n~~~~ Original file ~~~~");
                    Console.WriteLine(commitContent);
                    Console.WriteLine ("\n\n~~~~ Current file ~~~~");
                    Console.WriteLine(workingContent);
                }
            }
        }
    }
}

• Ref: https://libgit2.github.com/libgit2/ex/HEAD/cat-file.html
• Ref: https://github.com/libgit2/libgit2sharp/blob/vNext/LibGit2Sharp.Tests/BlobFixture.cs