Invalid history tracker with custom changes_method

[sivagollapalli]

      it "should allow an alternate method to be specified on object creation" do                             
        class CustomTracker < MyModel                                                                         
          field :key                                                                                          

          track_history on: :key, changes_method: :my_changes, track_create: true, track_update: true         

          def my_changes                                                                                      
            changes.merge(key: "Save history-#{key}")                                                         
          end                                                                                                 
        end                                                                                                   

        m = CustomTracker.create(key: "on object creation")                                                   
        history_track = m.history_tracks.last                                                                 
        expect(history_track.modified[:key]).to eq("Save history-on object creation")                         

        p history_track.inspect                                                                               

        m.update_attributes(key: "object updated")                                                            
        history_track = m.history_tracks.last                                                                 
        p history_track.inspect                                                                               
      end       

The above spec yields following output:

History Tracker on creation:

 #<Tracker _id: 5783a04ac5f169421e5905f9, created_at: 2016-07-11 13:34:02 UTC, updated_at: 2016-07-11 13:34:02 UTC, association_chain: [{\"name\"=>\"CustomTracker\", \"id\"=>BSON::ObjectId('5783a04ac5f169421e5905fa')}], modified: {\"key\"=>\"Save history-on object creation\"}, original: {}, version: 1, action: \"create\", scope: \"my_model\", modifier_id: nil>

History Tracker on updation:

"#<Tracker _id: 5783a04ac5f169421e5905fb, created_at: 2016-07-11 13:34:02 UTC, updated_at: 2016-07-11 13:34:02 UTC, association_chain: [{\"name\"=>\"CustomTracker\", \"id\"=>BSON::ObjectId('5783a04ac5f169421e5905fa')}], modified: {}, original: {\"key\"=>\"Save history-object updated\"}, version: 2, action: \"update\", scope: \"my_model\", modifier_id: nil>"

Updation history trackers inserts with empty modified value. Actually it shouldn't empty.

[sivagollapalli]

@dblock Just now I checked, since I defined changes.merge(key: "Save history-#{key}") in my model it overrides changes that are there on the object. So, modified value becomes empty. Is this valid case?

[dblock]

But wasn't that the whole point? I guess I don't understand what the original intent was anymore :)

[sivagollapalli]

@dblock I think we can't fix this as the user modifies changes happened on the object using changes.merge(key: "Save history-#{key}"). Do you think the same?

[dblock]

Backup. What did you want to happen in your initial example? I mean what was the purpose of changes.merge(key: "Save history-#{key}")?

[sivagollapalli]

The purpose of changes.merge(key: "Save history-#{key}")? is that I want to append Save history to the values before inserting into history tracker. But when I do changes.merge(key: "Save history-#{key}")? it inserts empty history tracker with modified value as empty while updating an object.

[dblock]

Ok, I understand. I think this should work. I would track where the modified values are being inserted and see why this is happening, I would expect it to work, too.

Maybe write actual specs first where you do a merge when key_changed? for all the CRUD scenarios? I can try to help fix.