In order to run examples, you will need to Install NodeGit first.

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Opening a Repository

This guide explains how to open a repository, and how to work with errors in a promise chain

View example source

Requiring NodeGit

In the guides directory, we like to keep our NodeGit relative to the project root.

var NodeGit = require("../../../");

However, in your project you will most likely be using the following command:

var NodeGit = require("nodegit");

Path to Repo

The only argument to the open method is a path to the repo on disk. Here we are calculating that from our current directory using the path object from node.

var pathToRepo = require("path").resolve("../my-git-projects/my-project");

You can also point it directly to a .git folder to open as well

var pathToRepo = require("path").resolve("../my-git-projects/my-project/.git");

This is not necessary though as the function will check the passed directory for the .git subdirectory

Open a Repo

Now that we have our path to the repo we wish to open we can do so by calling the open method on the NodeGit.Repository module

NodeGit.Repository.open(pathToRepo).then(function (repo) {
  // Inside of this function we have an open repo
});

*NOTE: We use promises to perform operations in NodeGit. This allows the node event loop to keep cycling through while under the hood our wrapped libgit2 code is performing the actions we requested and we’re not waiting for it.

This allows our apps to remain responsive and performant. However if you’re not used to promises then this can take some getting used to. If you need an introduction you can head over to https://www.promisejs.org/ for some tutorials.*

Handling errors

Promises will swallow errors if there isn’t code to explicitly handle them. You can do this through any of the following 3 ways.

Providing a second function to the .then method

You can pass a second function parameter to the .then method that will have the reason why a promise failed in it’s first argument.

NodeGit.Repository.open(pathToRepo).then(function (successfulResult) {
  // This is the first function of the then which contains the successfully
  // calculated result of the promise
}, function (reasonForFailure) {
  // This is the second function of the then which contains the reason the
  // promise failed
});

Including a .catch in a chain

You can also append a .catch to the end of a promise chain which will receive any promise failure that isn’t previously caught

NodeGit.Repository.open(pathToRepo).then(function (successfulResult) {
  // This is the first function of the then which contains the successfully
  // calculated result of the promise
})
.catch(function (reasonForFailure) {
  // failure is handled here
});

Finishing a chain with done

If you append a .done at the end of your chain, you will have any error that wasn’t previously handled by the above 2 methods thrown.

NodeGit.Repository.open(pathToRepo).then(function (successfulResult) {
  // This is the first function of the then which contains the successfully
  // calculated result of the promise
})
.done(function () {
  // If we have a .done then the error will be thrown if there was an error that
  // wasn't caught by either providing a 2nd function to the `.then` or a
  // `.catch` function
});