Refactor changing files in web UI

app/assets/javascripts/blob/blob_file_dropzone.js

@@ -35,7 +35,7 @@ export default class BlobFileDropzone {
           this.removeFile(file);
         });
         this.on('sending', function (file, xhr, formData) {
-          formData.append('target_branch', form.find('input[name="target_branch"]').val());
+          formData.append('branch_name', form.find('input[name="branch_name"]').val());
           formData.append('create_merge_request', form.find('.js-create-merge-request').val());
           formData.append('commit_message', form.find('.js-commit-message').val());
         });

app/controllers/concerns/creates_commit.rb

 module CreatesCommit
   extend ActiveSupport::Concern
+  def set_start_branch_to_branch_name
+    branch_exists = @repository.find_branch(@branch_name)
+    @start_branch = @branch_name if branch_exists
+  end
+
   def create_commit(service, success_path:, failure_path:, failure_view: nil, success_notice: nil)
-    set_commit_variables
+    if can?(current_user, :push_code, @project)
+      @project_to_commit_into = @project
+      @branch_name ||= @ref
+    else
+      @project_to_commit_into = current_user.fork_of(@project)
+      @branch_name ||= @project_to_commit_into.repository.next_branch('patch')
+    end
+
+    @start_branch ||= @ref || @branch_name
     commit_params = @commit_params.merge(
-      start_project: @mr_target_project,
-      start_branch: @mr_target_branch,
-      target_branch: @mr_source_branch
+      start_project: @project,
+      start_branch: @start_branch,
+      branch_name: @branch_name
     )
-    result = service.new(
-      @mr_source_project, current_user, commit_params).execute
+    result = service.new(@project_to_commit_into, current_user, commit_params).execute
     if result[:status] == :success
       update_flash_notice(success_notice)
@@ -72,30 +84,30 @@ module CreatesCommit
   def new_merge_request_path
     new_namespace_project_merge_request_path(
-      @mr_source_project.namespace,
-      @mr_source_project,
+      @project_to_commit_into.namespace,
+      @project_to_commit_into,
       merge_request: {
-        source_project_id: @mr_source_project.id,
-        target_project_id: @mr_target_project.id,
-        source_branch: @mr_source_branch,
-        target_branch: @mr_target_branch
+        source_project_id: @project_to_commit_into.id,
+        target_project_id: @project.id,
+        source_branch: @branch_name,
+        target_branch: @start_branch
       }
     )
   end
   def existing_merge_request_path
-    namespace_project_merge_request_path(@mr_target_project.namespace, @mr_target_project, @merge_request)
+    namespace_project_merge_request_path(@project.namespace, @project, @merge_request)
   end
   def merge_request_exists?
     return @merge_request if defined?(@merge_request)
-    @merge_request = MergeRequestsFinder.new(current_user, project_id: @mr_target_project.id).execute.opened.
-      find_by(source_branch: @mr_source_branch, target_branch: @mr_target_branch, source_project_id: @mr_source_project)
+    @merge_request = MergeRequestsFinder.new(current_user, project_id: @project.id).execute.opened.
+      find_by(source_project_id: @project_to_commit_into, source_branch: @branch_name, target_branch: @start_branch)
   end
   def different_project?
-    @mr_source_project != @mr_target_project
+    @project_to_commit_into != @project
   end
   def create_merge_request?
@@ -103,22 +115,6 @@ module CreatesCommit
     # as the target branch in the same project,
     # we don't want to create a merge request.
     params[:create_merge_request].present? &&
-      (different_project? || @mr_target_branch != @mr_source_branch)
-  end
-
-  def set_commit_variables
-    if can?(current_user, :push_code, @project)
-      @mr_source_project = @project
-      @target_branch ||= @ref
-    else
-      @mr_source_project = current_user.fork_of(@project)
-      @target_branch ||= @mr_source_project.repository.next_branch('patch')
-    end
-
-    # Merge request to this project
-    @mr_target_project = @project
-    @mr_target_branch ||= @ref || @target_branch
-
-    @mr_source_branch = @target_branch
+      (different_project? || @start_branch != @branch_name)
   end
 end

app/controllers/projects/application_controller.rb

@@ -89,9 +89,4 @@ class Projects::ApplicationController < ApplicationController
   def builds_enabled
     return render_404 unless @project.feature_available?(:builds, current_user)
   end
-
-  def update_ref
-    branch_exists = @repository.find_branch(@target_branch)
-    @ref = @target_branch if branch_exists
-  end
 end

app/controllers/projects/blob_controller.rb

@@ -25,10 +25,10 @@ class Projects::BlobController < Projects::ApplicationController
   end
   def create
-    update_ref
+    set_start_branch_to_branch_name
     create_commit(Files::CreateService, success_notice: "The file has been successfully created.",
-                                        success_path: -> { namespace_project_blob_path(@project.namespace, @project, File.join(@target_branch, @file_path)) },
+                                        success_path: -> { namespace_project_blob_path(@project.namespace, @project, File.join(@branch_name, @file_path)) },
                                         failure_view: :new,
                                         failure_path: namespace_project_new_blob_path(@project.namespace, @project, @ref))
   end
@@ -69,10 +69,10 @@ class Projects::BlobController < Projects::ApplicationController
   end
   def destroy
-    create_commit(Files::DestroyService, success_notice: "The file has been successfully deleted.",
-                                         success_path: -> { namespace_project_tree_path(@project.namespace, @project, @target_branch) },
-                                         failure_view: :show,
-                                         failure_path: namespace_project_blob_path(@project.namespace, @project, @id))
+    create_commit(Files::DeleteService, success_notice: "The file has been successfully deleted.",
+                                        success_path: -> { namespace_project_tree_path(@project.namespace, @project, @branch_name) },
+                                        failure_view: :show,
+                                        failure_path: namespace_project_blob_path(@project.namespace, @project, @id))
   end
   def diff
@@ -127,16 +127,16 @@ class Projects::BlobController < Projects::ApplicationController
   def after_edit_path
     from_merge_request = MergeRequestsFinder.new(current_user, project_id: @project.id).execute.find_by(iid: params[:from_merge_request_iid])
-    if from_merge_request && @target_branch == @ref
+    if from_merge_request && @branch_name == @ref
       diffs_namespace_project_merge_request_path(from_merge_request.target_project.namespace, from_merge_request.target_project, from_merge_request) +
         "##{hexdigest(@path)}"
     else
-      namespace_project_blob_path(@project.namespace, @project, File.join(@target_branch, @path))
+      namespace_project_blob_path(@project.namespace, @project, File.join(@branch_name, @path))
     end
   end
   def editor_variables
-    @target_branch = params[:target_branch]
+    @branch_name = params[:branch_name]
     @file_path =
       if action_name.to_s == 'create'

app/controllers/projects/commit_controller.rb

@@ -56,9 +56,7 @@ class Projects::CommitController < Projects::ApplicationController
     return render_404 if @start_branch.blank?
-    @target_branch = create_new_branch? ? @commit.revert_branch_name : @start_branch
-
-    @mr_target_branch = @start_branch
+    @branch_name = create_new_branch? ? @commit.revert_branch_name : @start_branch
     create_commit(Commits::RevertService, success_notice: "The #{@commit.change_type_title(current_user)} has been successfully reverted.",
                                           success_path: -> { successful_change_path }, failure_path: failed_change_path)
@@ -69,9 +67,7 @@ class Projects::CommitController < Projects::ApplicationController
     return render_404 if @start_branch.blank?
-    @target_branch = create_new_branch? ? @commit.cherry_pick_branch_name : @start_branch
-
-    @mr_target_branch = @start_branch
+    @branch_name = create_new_branch? ? @commit.cherry_pick_branch_name : @start_branch
     create_commit(Commits::CherryPickService, success_notice: "The #{@commit.change_type_title(current_user)} has been successfully cherry-picked.",
                                               success_path: -> { successful_change_path }, failure_path: failed_change_path)
@@ -84,7 +80,7 @@ class Projects::CommitController < Projects::ApplicationController
   end
   def successful_change_path
-    referenced_merge_request_url || namespace_project_commits_url(@project.namespace, @project, @target_branch)
+    referenced_merge_request_url || namespace_project_commits_url(@project.namespace, @project, @branch_name)
   end
   def failed_change_path

app/controllers/projects/tree_controller.rb

@@ -34,16 +34,16 @@ class Projects::TreeController < Projects::ApplicationController
   def create_dir
     return render_404 unless @commit_params.values.all?
-    update_ref
+    set_start_branch_to_branch_name
     create_commit(Files::CreateDirService,  success_notice: "The directory has been successfully created.",
-                                            success_path: namespace_project_tree_path(@project.namespace, @project, File.join(@target_branch, @dir_name)),
+                                            success_path: namespace_project_tree_path(@project.namespace, @project, File.join(@branch_name, @dir_name)),
                                             failure_path: namespace_project_tree_path(@project.namespace, @project, @ref))
   end
   private
   def assign_dir_vars
-    @target_branch = params[:target_branch]
+    @branch_name = params[:branch_name]
     @dir_name = File.join(@path, params[:dir_name])
     @commit_params = {

app/helpers/projects_helper.rb

@@ -272,14 +272,14 @@ module ProjectsHelper
     end
   end
-  def add_special_file_path(project, file_name:, commit_message: nil, target_branch: nil, context: nil)
+  def add_special_file_path(project, file_name:, commit_message: nil, branch_name: nil, context: nil)
     namespace_project_new_blob_path(
       project.namespace,
       project,
       project.default_branch || 'master',
       file_name:      file_name,
       commit_message: commit_message || "Add #{file_name.downcase}",
-      target_branch: target_branch,
+      branch_name: branch_name,
       context: context
     )
   end

app/helpers/tree_helper.rb

@@ -35,7 +35,7 @@ module TreeHelper
   end
   def on_top_of_branch?(project = @project, ref = @ref)
-    project.repository.branch_names.include?(ref)
+    project.repository.branch_exists?(ref)
   end
   def can_edit_tree?(project = nil, ref = nil)

app/services/commits/change_service.rb

 module Commits
-  class ChangeService < ::BaseService
-    ValidationError = Class.new(StandardError)
-    ChangeError = Class.new(StandardError)
-    def execute
-      @start_project = params[:start_project] || @project
-      @start_branch = params[:start_branch]
-      @target_branch = params[:target_branch]
+  class ChangeService < Commits::CreateService
+    def initialize(*args)
+      super
       @commit = params[:commit]
-
-      check_push_permissions
-
-      commit
-    rescue Repository::CommitError, Gitlab::Git::Repository::InvalidBlobName, GitHooksService::PreReceiveError,
-           ValidationError, ChangeError => ex
-      error(ex.message)
     end
     private
-    def commit
-      raise NotImplementedError
-    end
-
     def commit_change(action)
       raise NotImplementedError unless repository.respond_to?(action)
-      validate_target_branch if different_branch?
-
       repository.public_send(
         action,
         current_user,
         @commit,
-        @target_branch,
+        @branch_name,
         start_project: @start_project,
         start_branch_name: @start_branch)
-
-      success
     rescue Repository::CreateTreeError
       error_msg = "Sorry, we cannot #{action.to_s.dasherize} this #{@commit.change_type_title(current_user)} automatically.
-                     A #{action.to_s.dasherize} may have already been performed with this #{@commit.change_type_title(current_user)}, or a more recent commit may have updated some of its content."
+                   This #{@commit.change_type_title(current_user)} may already have been #{action.to_s.dasherize}ed, or a more recent commit may have updated some of its content."
       raise ChangeError, error_msg
     end
-
-    def check_push_permissions
-      allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@target_branch)
-
-      unless allowed
-        raise ValidationError.new('You are not allowed to push into this branch')
-      end
-
-      true
-    end
-
-    def validate_target_branch
-      result = ValidateNewBranchService.new(@project, current_user)
-        .execute(@target_branch)
-
-      if result[:status] == :error
-        raise ChangeError, "There was an error creating the source branch: #{result[:message]}"
-      end
-    end
-
-    def different_branch?
-      @start_branch != @target_branch || @start_project != @project
-    end
   end
 end

app/services/commits/cherry_pick_service.rb

 module Commits
   class CherryPickService < ChangeService
-    def commit
+    def create_commit!
       commit_change(:cherry_pick)
     end
   end

app/services/commits/create_service.rb

+module Commits
+  class CreateService < ::BaseService
+    ValidationError = Class.new(StandardError)
+    ChangeError = Class.new(StandardError)
+
+    def initialize(*args)
+      super
+
+      @start_project = params[:start_project] || @project
+      @start_branch = params[:start_branch]
+      @branch_name = params[:branch_name]
+    end
+
+    def execute
+      validate!
+
+      new_commit = create_commit!
+
+      success(result: new_commit)
+    rescue ValidationError, ChangeError, Gitlab::Git::Index::IndexError, Repository::CommitError, GitHooksService::PreReceiveError => ex
+      error(ex.message)
+    end
+
+    private
+
+    def create_commit!
+      raise NotImplementedError
+    end
+
+    def raise_error(message)
+      raise ValidationError, message
+    end
+
+    def different_branch?
+      @start_branch != @branch_name || @start_project != @project
+    end
+
+    def validate!
+      validate_permissions!
+      validate_on_branch!
+      validate_branch_existance!
+
+      validate_new_branch_name! if different_branch?
+    end
+
+    def validate_permissions!
+      allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@branch_name)
+
+      unless allowed
+        raise_error("You are not allowed to push into this branch")
+      end
+    end
+
+    def validate_on_branch!
+      if !@start_project.empty_repo? && !@start_project.repository.branch_exists?(@start_branch)
+        raise_error('You can only create or edit files when you are on a branch')
+      end
+    end
+
+    def validate_branch_existance!
+      if !project.empty_repo? && different_branch? && repository.branch_exists?(@branch_name)
+        raise_error("A branch called '#{@branch_name}' already exists. Switch to that branch in order to make changes")
+      end
+    end
+
+    def validate_new_branch_name!
+      result = ValidateNewBranchService.new(project, current_user).execute(@branch_name)
+
+      if result[:status] == :error
+        raise_error("Something went wrong when we tried to create '#{@branch_name}' for you: #{result[:message]}")
+      end
+    end
+  end
+end

app/services/commits/revert_service.rb

 module Commits
   class RevertService < ChangeService
-    def commit
+    def create_commit!
       commit_change(:revert)
     end
   end

app/services/files/base_service.rb

 module Files
-  class BaseService < ::BaseService
-    ValidationError = Class.new(StandardError)
-
-    def execute
-      @start_project = params[:start_project] || @project
-      @start_branch = params[:start_branch]
-      @target_branch = params[:target_branch]
+  class BaseService < Commits::CreateService
+    def initialize(*args)
+      super
+      @author_email = params[:author_email]
+      @author_name = params[:author_name]
       @commit_message = params[:commit_message]
-      @file_path      = params[:file_path]
-      @previous_path  = params[:previous_path]
-      @file_content   = if params[:file_content_encoding] == 'base64'
-                          Base64.decode64(params[:file_content])
-                        else
-                          params[:file_content]
-                        end
-      @last_commit_sha = params[:last_commit_sha]
-      @author_email    = params[:author_email]
-      @author_name     = params[:author_name]
-
-      # Validate parameters
-      validate
-
-      # Create new branch if it different from start_branch
-      validate_target_branch if different_branch?
-
-      result = commit
-      if result
-        success(result: result)
-      else
-        error('Something went wrong. Your changes were not committed')
-      end
-    rescue Repository::CommitError, Gitlab::Git::Repository::InvalidBlobName, GitHooksService::PreReceiveError, ValidationError => ex
-      error(ex.message)
-    end
-
-    private
-
-    def different_branch?
-      @start_branch != @target_branch || @start_project != @project
-    end
-
-    def file_has_changed?
-      return false unless @last_commit_sha && last_commit
-
-      @last_commit_sha != last_commit.sha
-    end
-
-    def raise_error(message)
-      raise ValidationError.new(message)
-    end
-
-    def validate
-      allowed = ::Gitlab::UserAccess.new(current_user, project: project).can_push_to_branch?(@target_branch)
-
-      unless allowed
-        raise_error("You are not allowed to push into this branch")
-      end
-
-      if !@start_project.empty_repo? && !@start_project.repository.branch_exists?(@start_branch)
-        raise ValidationError, 'You can only create or edit files when you are on a branch'
-      end
-
-      if !project.empty_repo? && different_branch? && repository.branch_exists?(@branch_name)
-        raise ValidationError, "A branch called #{@branch_name} already exists. Switch to that branch in order to make changes"
-      end
-    end
-    def validate_target_branch
-      result = ValidateNewBranchService.new(project, current_user).
-        execute(@target_branch)
-      if result[:status] == :error
-        raise_error("Something went wrong when we tried to create #{@target_branch} for you: #{result[:message]}")
-      end
+      @file_path = params[:file_path]
+      @previous_path = params[:previous_path]
+      @file_content = params[:file_content]
+      @file_content = Base64.decode64(@file_content) if params[:file_content_encoding] == 'base64'
     end
   end
 end

app/services/files/create_dir_service.rb

 module Files
   class CreateDirService < Files::BaseService
-    def commit
+    def create_commit!
       repository.create_dir(
         current_user,
         @file_path,
         message: @commit_message,
-        branch_name: @target_branch,
+        branch_name: @branch_name,
         author_email: @author_email,
         author_name: @author_name,
         start_project: @start_project,
         start_branch_name: @start_branch)
     end
-
-    def validate
-      super
-
-      unless @file_path =~ Gitlab::Regex.file_path_regex
-        raise_error(
-          'Your changes could not be committed, because the file path ' +
-          Gitlab::Regex.file_path_regex_message
-        )
-      end
-    end
   end
 end

app/services/files/create_service.rb

 module Files
   class CreateService < Files::BaseService
-    def commit
+    def create_commit!
       repository.create_file(
         current_user,
         @file_path,
         @file_content,
         message: @commit_message,
-        branch_name: @target_branch,
+        branch_name: @branch_name,
         author_email: @author_email,
         author_name: @author_name,
         start_project: @start_project,
         start_branch_name: @start_branch)
     end
-
-    def validate
-      super
-
-      if @file_content.nil?
-        raise_error("You must provide content.")
-      end
-
-      if @file_path =~ Gitlab::Regex.directory_traversal_regex
-        raise_error(
-          'Your changes could not be committed, because the file name ' +
-          Gitlab::Regex.directory_traversal_regex_message
-        )
-      end
-
-      unless @file_path =~ Gitlab::Regex.file_path_regex
-        raise_error(
-          'Your changes could not be committed, because the file name ' +
-          Gitlab::Regex.file_path_regex_message
-        )
-      end
-
-      unless project.empty_repo?
-        @file_path.slice!(0) if @file_path.start_with?('/')
-
-        blob = repository.blob_at_branch(@start_branch, @file_path)
-
-        if blob
-          raise_error('Your changes could not be committed because a file with the same name already exists')
-        end
-      end
-    end
   end
 end

app/services/files/destroy_service.rb → app/services/files/delete_service.rb

 module Files
-  class DestroyService < Files::BaseService
-    def commit
+  class DeleteService < Files::BaseService
+    def create_commit!
       repository.delete_file(
         current_user,
         @file_path,
         message: @commit_message,
-        branch_name: @target_branch,
+        branch_name: @branch_name,
         author_email: @author_email,
         author_name: @author_name,
         start_project: @start_project,

app/services/files/multi_service.rb

 module Files
   class MultiService < Files::BaseService
-    FileChangedError = Class.new(StandardError)
-
-    ACTIONS = %w[create update delete move].freeze
-
-    def commit
+    def create_commit!
       repository.multi_action(
         user: current_user,
         message: @commit_message,
-        branch_name: @target_branch,
+        branch_name: @branch_name,
         actions: params[:actions],
         author_email: @author_email,
         author_name: @author_name,
@@ -19,122 +15,17 @@ module Files
     private
-    def validate
+    def validate!
       super
-      params[:actions].each_with_index do |action, index|
-        if ACTIONS.include?(action[:action].to_s)
-          action[:action] = action[:action].to_sym
-        else
-          raise_error("Unknown action type `#{action[:action]}`.")
-        end
-
-        unless action[:file_path].present?
-          raise_error("You must specify a file_path.")
-        end
-
-        action[:file_path].slice!(0) if action[:file_path] && action[:file_path].start_with?('/')
-        action[:previous_path].slice!(0) if action[:previous_path] && action[:previous_path].start_with?('/')
-
-        regex_check(action[:file_path])
-        regex_check(action[:previous_path]) if action[:previous_path]
-
-        if project.empty_repo? && action[:action] != :create
-          raise_error("No files to #{action[:action]}.")
-        end
-
-        validate_file_exists(action)
-
-        case action[:action]
-        when :create
-          validate_create(action)
-        when :update
-          validate_update(action)
-        when :delete
-          validate_delete(action)
-        when :move
-          validate_move(action, index)
-        end
-      end
-    end
-
-    def validate_file_exists(action)
-      return if action[:action] == :create
-
-      file_path = action[:file_path]
-      file_path = action[:previous_path] if action[:action] == :move
-
-      blob = repository.blob_at_branch(params[:branch], file_path)
-
-      unless blob
-        raise_error("File to be #{action[:action]}d `#{file_path}` does not exist.")
+      params[:actions].each do |action|
+        validate_action!(action)
       end
     end
-    def last_commit
-      Gitlab::Git::Commit.last_for_path(repository, @start_branch, @file_path)
-    end
-
-    def regex_check(file)
-      if file =~ Gitlab::Regex.directory_traversal_regex
-        raise_error(
-          'Your changes could not be committed, because the file name, `' +
-          file +
-          '` ' +
-          Gitlab::Regex.directory_traversal_regex_message
-        )
-      end
-
-      unless file =~ Gitlab::Regex.file_path_regex
-        raise_error(
-          'Your changes could not be committed, because the file name, `' +
-          file +
-          '` ' +
-          Gitlab::Regex.file_path_regex_message
-        )
-      end
-    end
-
-    def validate_create(action)
-      return if project.empty_repo?
-
-      if repository.blob_at_branch(params[:branch], action[:file_path])
-        raise_error("Your changes could not be committed because a file with the name `#{action[:file_path]}` already exists.")
-      end
-
-      if action[:content].nil?
-        raise_error("You must provide content.")
-      end
-    end
-
-    def validate_update(action)
-      if action[:content].nil?
-        raise_error("You must provide content.")
-      end
-
-      if file_has_changed?
-        raise FileChangedError.new("You are attempting to update a file `#{action[:file_path]}` that has changed since you started editing it.")
-      end
-    end
-
-    def validate_delete(action)
-    end
-
-    def validate_move(action, index)
-      if action[:previous_path].nil?
-        raise_error("You must supply the original file path when moving file `#{action[:file_path]}`.")
-      end
-
-      blob = repository.blob_at_branch(params[:branch], action[:file_path])
-
-      if blob
-        raise_error("Move destination `#{action[:file_path]}` already exists.")
-      end
-
-      if action[:content].nil?
-        blob = repository.blob_at_branch(params[:branch], action[:previous_path])
-        blob.load_all_data!(repository) if blob.truncated?
-        params[:actions][index][:content] = blob.data
+    def validate_action!(action)
+      unless Gitlab::Git::Index::ACTIONS.include?(action[:action].to_s)
+        raise_error("Unknown action '#{action[:action]}'")
       end
     end
   end

app/services/files/update_service.rb

@@ -2,10 +2,16 @@ module Files
   class UpdateService < Files::BaseService
     FileChangedError = Class.new(StandardError)
-    def commit
+    def initialize(*args)
+      super
+
+      @last_commit_sha = params[:last_commit_sha]
+    end
+
+    def create_commit!
       repository.update_file(current_user, @file_path, @file_content,
                              message: @commit_message,
-                             branch_name: @target_branch,
+                             branch_name: @branch_name,
                              previous_path: @previous_path,
                              author_email: @author_email,
                              author_name: @author_name,
@@ -15,21 +21,23 @@ module Files
     private
-    def validate
-      super
-
-      if @file_content.nil?
-        raise_error("You must provide content.")
-      end
-      if file_has_changed?
-        raise FileChangedError.new("You are attempting to update a file that has changed since you started editing it.")
-      end
+    def file_has_changed?
+      return false unless @last_commit_sha && last_commit
+      @last_commit_sha != last_commit.sha
     end
     def last_commit
       @last_commit ||= Gitlab::Git::Commit.
         last_for_path(@start_project.repository, @start_branch, @file_path)
     end
+
+    def validate!
+      super
+
+      if file_has_changed?
+        raise FileChangedError, "You are attempting to update a file that has changed since you started editing it."
+      end
+    end
   end
 end

app/services/validate_new_branch_service.rb

@@ -8,10 +8,7 @@ class ValidateNewBranchService < BaseService
       return error('Branch name is invalid')
     end
-    repository = project.repository
-    existing_branch = repository.find_branch(branch_name)
-
-    if existing_branch
+    if project.repository.branch_exists?(branch_name)
       return error('Branch already exists')
     end

app/views/projects/blob/edit.html.haml

@@ -9,7 +9,7 @@
   - if @conflict
     .alert.alert-danger
       Someone edited the file the same time you did. Please check out
-      = link_to "the file", namespace_project_blob_path(@project.namespace, @project, tree_join(@target_branch, @file_path)), target: "_blank", rel: 'noopener noreferrer'
+      = link_to "the file", namespace_project_blob_path(@project.namespace, @project, tree_join(@branch_name, @file_path)), target: "_blank", rel: 'noopener noreferrer'
       and make sure your changes will not unintentionally remove theirs.
   .editor-title-row
     %h3.page-title.blob-edit-page-title