Writing a commit object to the database
by Jakub Narębski, Rasmus Voss, Aske Olsson, Ferdinando Santacroce
Git: Mastering Version Control
- Git: Mastering Version Control
- Table of Contents
- Git: Mastering Version Control
- Git: Mastering Version Control
- Credits
- Preface
- I. Module 1
- 1. Getting Started with Git
- 2. Git Fundamentals – Working Locally
- 3. Git Fundamentals – Working Remotely
- 4. Git Fundamentals – Niche Concepts, Configurations, and Commands
- Dissecting the Git configuration
- Configuration architecture
- Configuration levels
- Listing configurations
- Editing configuration files manually
- Setting up other environment configurations
- Basic configurations
- 5. Obtaining the Most – Good Commits and Workflows
- The art of committing
- Adopting a workflow – a wise act
- Summary
- 6. Migrating to Git
- 7. Git Resources
- II. Module 2
- 1. Navigating Git
- 2. Configuration
- 3. Branching, Merging, and Options
- 4. Rebase Regularly and Interactively, and Other Use Cases
- 5. Storing Additional Information in Your Repository
- 6. Extracting Data from the Repository
- 7. Enhancing Your Daily Work with Git Hooks, Aliases, and Scripts
- Introduction
- Using a branch description in the commit message
- Creating a dynamic commit message template
- Using external information in the commit message
- Preventing the push of specific commits
- Configuring and using Git aliases
- Configuring and using Git scripts
- Setting up and using a commit template
- 8. Recovering from Mistakes
- Introduction
- Undo – remove a commit completely
- Undo – remove a commit and retain the changes to files
- Undo – remove a commit and retain the changes in the staging area
- Undo – working with a dirty area
- Redo – recreate the latest commit with new changes
- Revert – undo the changes introduced by a commit
- Reverting a merge
- Viewing past Git actions with git reflog
- Finding lost changes with git fsck
- 9. Repository Maintenance
- Introduction
- Pruning remote branches
- Running garbage collection manually
- Turning off automatic garbage collection
- Splitting a repository
- Rewriting history – changing a single file
- Back up your repositories as mirror repositories
- A quick submodule how-to
- Subtree merging
- Submodule versus subtree merging
- 10. Patching and Offline Sharing
- 11. Git Plumbing and Attributes
- Introduction
- Displaying the repository information
- Displaying the tree information
- Displaying the file information
- Writing a blob object to the database
- Writing a tree object to the database
- Writing a commit object to the database
- Keyword expansion with attribute filters
- Metadata diff of binary files
- Storing binaries elsewhere
- Checking the attributes of a file
- Attributes to export an archive
- 12. Tips and Tricks
- III. Module 3
- 1. Git Basics in Practice
- An introduction to version control and Git
- Git by example
- Repository setup
- Creating a Git repository
- Cloning the repository and creating the first commit
- Publishing changes
- Examining history and viewing changes
- Renaming and moving files
- Updating your repository (with merge)
- Creating a tag
- Resolving a merge conflict
- Adding files in bulk and removing files
- Undoing changes to a file
- Creating a new branch
- Merging a branch (no conflicts)
- Undoing an unpublished merge
- Summary
- 2. Exploring Project History
- 3. Developing with Git
- 4. Managing Your Worktree
- Ignoring files
- File attributes
- Fixing mistakes with the reset command
- Stashing away your changes
- Managing worktrees and the staging area
- Multiple working directories
- Summary
- 5. Collaborative Development with Git
- 6. Advanced Branching Techniques
- Types and purposes of branches
- Branching workflows and release engineering
- Interacting with branches in remote repositories
- Summary
- 7. Merging Changes Together
- 8. Keeping History Clean
- An introduction to Git internals
- Rewriting history
- Amending history without rewriting
- Summary
- 9. Managing Subprojects – Building a Living Framework
- Managing library and framework dependencies
- Managing large Git repositories
- Summary
- 10. Customizing and Extending Git
- 11. Git Administration
- 12. Git Best Practices
- 1. Git Basics in Practice
- A. Bibliography
- Index
- Configuration architecture
- Dissecting the Git configuration
Now that we have created both blob and tree objects, the next step in the data model is to create the actual commit object.
Again, we'll use the repository created in the previous examples with the different objects written to the database.
As we saw in Chapter 1, Navigating Git, a commit object consists of the author and committer information, a root tree object, a parent commit (except for the first commit), and a commit message. We have the root tree object generated in the last example, and Git will pick up the author and committer information from the configuration. So, all we need to do is create a commit message and write the commit object. We can do this for each of the tree objects we created previously:
$ echo 'Initial commit - Good contents' | git commit-tree 4c4493f8 40f4783c37e7cb9d07a4a71100acf4c474a376b0 $ echo 'Second commit - Better contents' | git commit-tree -p 40f4783 2b969743 991ad244c6fdc84a983543cd8f2e89deca0eff29 $ echo 'Adds a subdirectory' | git commit-tree -p 991ad244 9387b1a7 e89518224a971df09a00242355b62278964d6811
Three commit objects are created. The -p switch in the latter two commands tells Git to use the commit specified as a parent commit for the one to be created. Git will use the author and committer information it can find through the configuration options. We can verify that the commits were created with the cat-file command, just like we did with the blobs and trees:
$ git cat-file -p 40f4783c37e7cb9d07a4a71100acf4c474a376b0 tree 4c4493f8029d491d280695e263e24772ab6962ce author Aske Olsson <[email protected]> 1398270736 +0200 committer Aske Olsson <[email protected]> 1398270736 +0200 Initial commit - Good contents $ git cat-file -t 40f4783c37e7cb9d07a4a71100acf4c474a376b0 commit $ git cat-file -p 991ad244c6fdc84a983543cd8f2e89deca0eff29 tree 2b9697438318f3a62a5e85d14a3b52d69b962907 parent 40f4783c37e7cb9d07a4a71100acf4c474a376b0 author Aske Olsson <[email protected]> 1398270736 +0200 committer Aske Olsson <[email protected]> 1398270736 +0200 Second commit - Better contents $ git cat-file -t 991ad244c6fdc84a983543cd8f2e89deca0eff29 commit $ git cat-file -p e89518224a971df09a00242355b62278964d6811 tree 5c23c103aeaa360342f36fe13a673fa473f665b8 parent 991ad244c6fdc84a983543cd8f2e89deca0eff29 author Aske Olsson <[email protected]> 1398270736 +0200 committer Aske Olsson <[email protected]> 1398270736 +0200 Adds a subdirectory $ git cat-file -t e89518224a971df09a00242355b62278964d6811 commit
As we specified, parent commits for the last two commit objects we made we actually created Git's history in the repository, which we can view with the log command. We'll need to tell the log command to show the history from the latest commit, as we haven't updated any branches to point to it:
$ git log e89518224a971df09a00242355b62278964d6811 commit e89518224a971df09a00242355b62278964d6811 Author: Aske Olsson <[email protected]> Date: Wed Apr 23 18:32:16 2014 +0200 Adds a subdirectory commit 991ad244c6fdc84a983543cd8f2e89deca0eff29 Author: Aske Olsson <[email protected]> Date: Wed Apr 23 18:32:16 2014 +0200 Second commit - Better contents commit 40f4783c37e7cb9d07a4a71100acf4c474a376b0 Author: Aske Olsson <[email protected]> Date: Wed Apr 23 18:32:16 2014 +0200 Initial commit - Good contents
-
No Comment
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.