# Updating Go Import Statements using Comby

<p className="subtitle">
	This guide explains how to use Comby to update Go import statements in a
	batch change.
</p>

This batch change example rewrites Go import paths for the `log15` package from `gopkg.in/inconshreveable/log15.v2` to `github.com/inconshreveable/log15` using [Comby](https://comby.dev/).

It can handle single-package import statements like the following:

```go
import "gopkg.in/inconshreveable/log15.v2"
```

Single-package imports with an alias:

```go
import log15 "gopkg.in/inconshreveable/log15.v2"
```

And multi-package import statements with or without an alias:

```go
import (
	"io"

	"github.com/pkg/errors"
	"gopkg.in/inconshreveable/log15.v2"
)
```

## Prerequisites

<Callout type="tip">
	It's recommended to use the latest version of Sourcegraph when working with
	Batch Changes.
</Callout>

Before you start, it's better to read the following docs:

-   [Batch Changes Quickstart](/batch-changes/quickstart)
-   [How to create and run a Batch Spec?](/batch-changes/create-a-batch-change)

## Create the batch spec

Save the following batch spec YAML as `update-log15-import.batch.yaml`:

```yaml
name: update-log15-import
description: This batch change updates Go import paths for the `log15` package from `gopkg.in/inconshreveable/log15.v2` to `github.com/inconshreveable/log15` using [Comby](https://comby.dev/)

# Find all repositories that contain the import we want to change.
on:
    - repositoriesMatchingQuery: lang:go gopkg.in/inconshreveable/log15.v2

# In each repository
steps:
    # we first replace the import when it's part of a multi-package import statement
    - run: comby -in-place 'import (:[before]"gopkg.in/inconshreveable/log15.v2":[after])' 'import (:[before]"github.com/inconshreveable/log15":[after])' .go -matcher .go -exclude-dir .,vendor
      container: comby/comby
    # ... and when it's a single import line.
    - run: comby -in-place 'import:[alias]"gopkg.in/inconshreveable/log15.v2"' 'import:[alias]"github.com/inconshreveable/log15"' .go -matcher .go -exclude-dir .,vendor
      container: comby/comby

# Describe the changeset (e.g., GitHub pull request) you want for each repository.
changesetTemplate:
    title: Update import path for log15 package to use GitHub
    body: Updates Go import paths for the `log15` package from `gopkg.in/inconshreveable/log15.v2` to `github.com/inconshreveable/log15` using [Comby](https://comby.dev/)
    branch: batch-changes/update-log15-import # Push the commit to this branch.
    commit:
        message: Fix import path for log15 package
    published: false
```

## Create the batch change

-   In your terminal, run the following command:

```shell
src batch preview -f update-log15-import.batch.yaml
```

-   Wait for it to run and compute the changes for each repository
-   Open the preview URL that the command printed out
-   Examine the preview. Confirm that the changesets are the ones you intended to track. If not, edit the batch spec and then re-run the command above
-   Click the **Apply** button to create the batch change
-   Feel free to then publish the changesets (i.e., create pull requests and merge requests) by [modifying the `published` attribute in the batch spec](/batch-changes/batch-spec-yaml-reference#changesettemplatepublished) and re-running the `src batch preview` command