How to extract or modify a small piece of commited code in a far away previous commitiece code

Question

I need to extract a snippet of code in app/views/cgi_testing_seeds/index.html.haml, form this commit '77df270', because it should be owned by other commit.

It's very complicated to revert or rollback to that commit '77df270', Then redo all the remaining commits again,

For example If I only want to revert the code of index method in the CgiTestingSeedsController.rb,

And add it into the commit 4b733c5 , how to ?

Or extract the code of the method and keep it in staged status, how to ?

What's an easier to do this in Git.

Brief log

4b733c5 - (HEAD, feature/testing_seeds_model) Scaffold:Testing seed and generate testing data via 'faker gem' (7 minutes ago) <poc7667>
2fd8204 - (develop) Merge branch 'hotfix/wrong_column_names_in_CGIparamters' into develop (4 days ago) <poc7667>
052e2ff - Remove 'name' in 'cgi_attributes' and fix wrong name for 'default_value' (4 days ago) <poc7667>
77df270 - Scaffold: CgiTestingSeed (2 days ago) <poc7667>

Changed file in the commit 77df270

77df270 - Scaffold: CgiTestingSeed (2 days ago) <poc7667>
app/assets/javascripts/cgi_testing_seeds.js.coffee
app/controllers/cgi_testing_seeds_controller.rb
app/helpers/cgi_testing_seeds_helper.rb

CgiTestingSeedsController.rb in the commit 77df270

class CgiTestingSeedsController < ApplicationController
  before_action :set_cgi_testing_seed, only: [:show, :edit, :update, :destroy]

  # GET /cgi_testing_seeds
  # GET /cgi_testing_seeds.json
  def index
    @cgi_testing_seeds = CgiTestingSeed.all
  end

  # GET /cgi_testing_seeds/1
  # GET /cgi_testing_seeds/1.json
  def show
  end

It's quite vague what you actually want to do, but you probably need cherrypicking. https://www.kernel.org/pub/software/scm/git/docs/git-cherry-pick.html. — Willem Van Onsem, May 26 '14 at 02:18
@Basilevs But I should remove the piece code from the commit, right? Because it shouldn't occur there . — newBike, May 26 '14 at 02:47
If you want to remove a portion of code, you should've said so. "Extract" is a bad wording for that. — Basilevs, May 26 '14 at 08:16
If you want to alter your commit history you'll have to replace everything from that change forward using rebase/cherry-pick/filter-branch/whathaveyou. — jthill, May 26 '14 at 18:08

score 1 · Answer 1 · edited May 23 '17 at 12:20

For example If I only want to revert the code of index method in the CgiTestingSeedsController.rb,

You could consider making a patch, using git diff:

git diff 77df270 77df270~ > revert.diff
vi revert.diff # leave only changes regarding the `index` method

Note the order 77df270 77df270~: a diff from what you changed (77df270) to what you had before the changes: 77df270~: this is done to revert the changes in 77df270.

And add it into the commit 4b733c5 , how to ?

You can apply your diff patch file using git apply (as in here):

git apply revert.diff

Since it doesn't create a commit, you can then use git commit --amend to modify your current latest commit.

How to extract or modify a small piece of commited code in a far away previous commitiece code

Brief log

Changed file in the commit 77df270

CgiTestingSeedsController.rb in the commit 77df270

1 Answers1