nodegit/example/general.js at v0.2.2 · nodegit/nodegit · GitHub

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var nodegit = require('../');

var path = require('path');

var Promise = require('nodegit-promise');

var oid;

var odb;

var repo;

// **nodegit** is a javascript library for node.js that wraps libgit2, a

// pure C implementation of the Git core. It provides an asynchronous

// interface around any functions that do I/O, and a sychronous interface

// around the rest.

// This file is an example of using that API in a real, JS file.

// **libgit2** (for the most part) only implements the core plumbing

// functions, not really the higher level porcelain stuff. For a primer on

// Git Internals that you will need to know to work with Git at this level,

// check out [Chapter 9][pg] of the Pro Git book.

// Nearly, all git operations in the context of a repository.

// To open a repository,

nodegit.Repository.open(path.resolve(__dirname, '../.git'))

.then(function(repoResult) {

repo = repoResult;

console.log("Opened repository.");

// ### SHA-1 Value Conversions

// Objects in git (commits, blobs, etc.) are referred to by their SHA value

// **nodegit** uses a simple wrapper around hash values called an `Oid`.

// The oid validates that the SHA is well-formed.

oid = nodegit.Oid.fromString('c27d9c35e3715539d941254f2ce57042b978c49c');

// Most functions in in **nodegit** that take an oid will also take a

// string, so for example, you can look up a commit by a string SHA or

// an Oid, but but any functions that create new SHAs will always return

// an Oid.

// If you have a oid, you can easily get the hex value of the SHA again.

console.log("Sha hex string:", oid.toString());

// ### Working with the Object Database

// **libgit2** provides [direct access][odb] to the object database. The

// object database is where the actual objects are stored in Git. For

// working with raw objects, we'll need to get this structure from the

// repository.

return repo.odb();

}).then(function(odbResult) {

odb = odbResult;

// We can read raw objects directly from the object database if we have

// the oid (SHA) of the object. This allows us to access objects without

// knowing thier type and inspect the raw bytes unparsed.

return odb.read(oid);

}).then(function(object) {

// A raw object only has three properties - the type (commit, blob, tree

// or tag), the size of the raw data and the raw, unparsed data itself.

// For a commit or tag, that raw data is human readable plain ASCII

// text. For a blob it is just file contents, so it could be text or

// binary data. For a tree it is a special binary format, so it's unlikely

// to be hugely helpful as a raw object.

var data = object.data();

var type = object.type();

var size = object.size();

console.log("Object size and type:", size, type);

}).then(function() {

// You can also write raw object data to Git. This is pretty cool because

// it gives you direct access to the key/value properties of Git. Here

// we'll write a new blob object that just contains a simple string.

// Notice that we have to specify the object type.

return odb.write("test data", "test data".length, nodegit.Object.TYPE.BLOB);

}).then(function(oid) {

// Now that we've written the object, we can check out what SHA1 was

// generated when the object was written to our database.

console.log("Written Object: ", oid.toString());

}).then(function() {

// ### Object Parsing

// libgit2 has methods to parse every object type in Git so you don't have

// to work directly with the raw data. This is much faster and simpler

// than trying to deal with the raw data yourself.

// #### Commit Parsing

// [Parsing commit objects][pco] is simple and gives you access to all the

// data in the commit - the author (name, email, datetime), committer

// (same), tree, message, encoding and parent(s).

oid = nodegit.Oid.fromString("698c74e817243efe441a5d1f3cbaf3998282ca86");

// Many methods in **nodegit** are asynchronous, because they do file

// or network I/O. By convention, all asynchronous methods are named

// imperatively, like `getCommit`, `open`, `read`, `write`, etc., whereas

// synchronous methods are named nominatively, like `type`, `size`, `name`.

return repo.getCommit(oid);

}).then(function(commit) {

// Each of the properties of the commit object are accessible via methods,

// including commonly needed variations, such as `git_commit_time` which

// returns the author time and `git_commit_message` which gives you the

// commit message.

console.log("Commit:", commit.message(), commit.author().name(), commit.date());

// Commits can have zero or more parents. The first (root) commit will

// have no parents, most commits will have one (i.e. the commit it was

// based on) and merge commits will have two or more. Commits can

// technically have any number, though it's rare to have more than two.

return commit.getParents();

}).then(function(parents) {

parents.forEach(function(parent) {

console.log("Parent:", parent.toString());

});

}).then(function() {

// #### Writing Commits

// nodegit provides a couple of methods to create commit objects easily as

// well.

var author = nodegit.Signature.create("Scott Chacon", "schacon@gmail.com", 123456789, 60);

var committer = nodegit.Signature.create("Scott A Chacon", "scott@github.com", 987654321, 90);

// Commit objects need a tree to point to and optionally one or more

// parents. Here we're creating oid objects to create the commit with,

// but you can also use existing ones:

var treeId = nodegit.Oid.fromString("4170d10f19600b9cb086504e8e05fe7d863358a2");

var parentId = nodegit.Oid.fromString("eebd0ead15d62eaf0ba276da53af43bbc3ce43ab");

return repo.getTree(treeId).then(function(tree) {

return repo.getCommit(parentId).then(function(parent) {

// Here we actually create the commit object with a single call with all

// the values we need to create the commit. The SHA key is written to the

// `commit_id` variable here.

return repo.createCommit(

null /* do not update the HEAD */,

author,

committer,

"example commit",

tree,

[parent]);

}).then(function(oid) {

console.log("New Commit:", oid.toString());

});

}).then(function() {

// #### Tag Parsing

// You can parse and create tags with the [tag management API][tm], which

// functions very similarly to the commit lookup, parsing and creation

// methods, since the objects themselves are very similar.

oid = nodegit.Oid.fromString("dcc4aa9fcdaced037434cb149ed3b6eab4d0709d");

return repo.getTag(oid);

}).then(function(tag) {

// Now that we have the tag object, we can extract the information it

// generally contains: the target (usually a commit object), the type of

// the target object (usually 'commit'), the name ('v1.0'), the tagger (a

// git_signature - name, email, timestamp), and the tag message.

console.log(tag.name(), tag.targetType(), tag.message());

return tag.target();

}).then(function (target) {

console.log("Target is commit:", target.isCommit());

}).then(function() {

// #### Tree Parsing

// A Tree is how Git represents the state of the filesystem

// at a given revision. In general, a tree corresponds to a directory,

// and files in that directory are either files (blobs) or directories.

// [Tree parsing][tp] is a bit different than the other objects, in that

// we have a subtype which is the tree entry. This is not an actual

// object type in Git, but a useful structure for parsing and traversing

// tree entries.

oid = nodegit.Oid.fromString("e1b0c7ea57bfc5e30ec279402a98168a27838ac9");

return repo.getTree(oid);

}).then(function(tree) {

console.log("Tree Size:", tree.entryCount());

function dfs(tree) {

var promises = [];

tree.entries().forEach(function(entry) {

if (entry.isDirectory()) {

promises.push(entry.getTree().then(dfs));

} else if (entry.isFile()) {

console.log("Tree Entry:", entry.filename());

}

});

return Promise.all(promises);

}

return dfs(tree).then(function() {

// You can also access tree entries by path if you know the path of the

// entry you're looking for.

return tree.getEntry("example/general.js").then(function(entry) {

// Entries which are files have blobs associated with them:

entry.getBlob(function(error, blob) {

console.log("Blob size:", blob.size());

});

}).then(function() {

// #### Blob Parsing

// The last object type is the simplest and requires the least parsing

// help. Blobs are just file contents and can contain anything, there is

// no structure to it. The main advantage to using the [simple blob

// api][ba] is that when you're creating blobs you don't have to calculate

// the size of the content. There is also a helper for reading a file

// from disk and writing it to the db and getting the oid back so you

// don't have to do all those steps yourself.

oid = nodegit.Oid.fromString("991c06b7b1ec6f939488427e4b41a4fa3e1edd5f");

return repo.getBlob(oid);

}).then(function(blob) {

// You can access a node.js Buffer with the raw contents of the blob directly.

// Note that this buffer may not be contain ASCII data for certain blobs

// (e.g. binary files).

var buffer = blob.content();

// If you know that the blob is UTF-8, however,

console.log("Blob contents:", blob.toString().slice(0, 38));

}).then(function() {

// ### Revwalking

// The libgit2 [revision walking api][rw] provides methods to traverse the

// directed graph created by the parent pointers of the commit objects.

// Since all commits point back to the commit that came directly before

// them, you can walk this parentage as a graph and find all the commits

// that were ancestors of (reachable from) a given starting point. This

// can allow you to create `git log` type functionality.

oid = nodegit.Oid.fromString("698c74e817243efe441a5d1f3cbaf3998282ca86");

// To use the revwalker, create a new walker, tell it how you want to sort

// the output and then push one or more starting points onto the walker.

// If you want to emulate the output of `git log` you would push the SHA

// of the commit that HEAD points to into the walker and then start

// traversing them. You can also 'hide' commits that you want to stop at

// or not see any of their ancestors. So if you want to emulate `git log

// branch1..branch2`, you would push the oid of `branch2` and hide the oid

// of `branch1`.

var revWalk = repo.createRevWalk();

revWalk.sorting(nodegit.Revwalk.SORT.TOPOLOGICAL, nodegit.Revwalk.SORT.REVERSE);

revWalk.push(oid);

// Now that we have the starting point pushed onto the walker, we start

// asking for ancestors. It will return them in the sorting order we asked

// for as commit oids. We can then lookup and parse the commited pointed

// at by the returned OID; note that this operation is specially fast

// since the raw contents of the commit object will be cached in memory

function walk() {

return revWalk.next().then(function(oid) {

if (!oid) return;

return repo.getCommit(oid).then(function(commit) {

console.log("Commit:", commit.toString());

return walk();

});

}

return walk();

}).then(function() {

// ### Index File Manipulation

// The [index file API][gi] allows you to read, traverse, update and write

// the Git index file (sometimes thought of as the staging area).

return repo.openIndex();

}).then(function(index) {

// For each entry in the index, you can get a bunch of information

// including the SHA (oid), path and mode which map to the tree objects

// that are written out. It also has filesystem properties to help

// determine what to inspect for changes (ctime, mtime, dev, ino, uid,

// gid, file_size and flags) All these properties are exported publicly in

// the `IndexEntry` class

index.entries().forEach(function(entry) {

console.log("Index Entry:", entry.path(), entry.mtime().seconds());

});

}).then(function() {

// ### References

// The [reference API][ref] allows you to list, resolve, create and update

// references such as branches, tags and remote references (everything in

// the .git/refs directory).

return repo.getReferenceNames(nodegit.Reference.TYPE.ALL);

}).then(function(referenceNames) {

var promises = [];

referenceNames.forEach(function(referenceName) {

promises.push(repo.getReference(referenceName).then(function(reference) {

if (reference.isConcrete()) {

console.log("Reference:", referenceName, reference.target());

} else if (reference.isSymbolic()) {

console.log("Reference:", referenceName, reference.symbolicTarget());

}

}));

});

return Promise.all(promises);

}).done(function() {

console.log("Done!");

});

nodegit/example/general.js at v0.2.2 · nodegit/nodegit · GitHub

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