Adding and committing a new file with git2go

I am currently struggling to stage and commit a file to a git repository in memory (i.e. without writing a file to disk, adding and committing it)

Here's a shortened version of my code; it almost works

package main
import (
"fmt"
"gopkg.in/libgit2/git2go.v25"
"time"
)
func main() {
sig := &git.Signature{
Name:  "Some Person",
Email: "somebody@something.org",
When:  time.Now(),
}
repo, err := git.OpenRepository("./repo")
check(err)
defer repo.Free()
content := []byte("hello world")
index, err := repo.Index()
check(err)
oid, err := repo.CreateBlobFromBuffer(content)
check(err)
ie := git.IndexEntry{
Mode: git.FilemodeBlob,
Id:   oid,
Path: "documents/document_9.md",
}
err = index.Add(&ie)
check(err)
treeId, err := index.WriteTree()
check(err)
tree, err := repo.LookupTree(treeId)
check(err)
index.Write()
currentBranch, err := repo.Head()
check(err)
currentTip, err := repo.LookupCommit(currentBranch.Target())
check(err)
commitId, err := repo.CreateCommit("HEAD", sig, sig, "A new commit", tree, currentTip)
check(err)
fmt.Println(commitId)
}
func check(err error) {
if err != nil {
panic(err)
}
}

However, when I run it and look in ./repo, something's not quite right. As you can see from git status, the new document_9.md file is marked as being deleted (i.e. git knows about it but it's not present)

❯ git status
On branch master
Changes not staged for commit:
(use "git add/rm <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
deleted:    documents/document_9.md

Looking at the log, it's confirmed that the commit actually worked:

❯ git log --patch
commit a609b43e6a3f7da7d0589971ab0f64f3f432e76c
Author: Some Person <somebody@something.org>
Date:   Thu Mar 23 19:43:56 2017 +0000
a new commit
diff --git a/documents/document_9.md b/documents/document_9.md
new file mode 100644
index 0000000..95d09f2
--- /dev/null
+++ b/documents/document_9.md
@@ -0,0 +1 @@
+hello world
\ No newline at end of file
commit 668762279b51483c05dbdedcf3c599a1b41c203b
Author: Original Committer <someguy@something.com>
Date:   Thu Mar 23 19:42:52 2017 +0000
First commit
diff --git a/documents/docment_1.md b/documents/docment_1.md
new file mode 100644
index 0000000..2965834
--- /dev/null
+++ b/documents/docment_1.md
@@ -0,0 +1 @@
+# Hello World

I believe that I'm missing a step. Somehow I need to ensure that my commit is 'synced' with the filesystem. I thought that (based on the documentation), this was achieved by index.Write() and index.WriteTree(), but I can't get it to work.

Any nudge in the right direction would be much appreciated.

If you want the working directory to match the state of the new HEAD commit then you need to check it out (e.g. with the go equivalent of git_checkout_head).

git_index_write_tree writes a tree object to the object database and git_index_write writes the in-memory representation of the index out to disk. Neither affect the working directory.