View source for E1645

= '''E1645: Refactoring TreeDisplayController''' =

__TOC__

=Project Links=
[https://github.com/expertiza/expertiza Github Repo]<br>
[https://github.com/expertiza/expertiza/pull/744 Expertize Pull Request] <br>
[https://travis-ci.org/expertiza/expertiza/builds/171173212 Travis CI Test Cases Passes] <br>


=Setup - How To View Our Expertiza Fork Running on AWS=
NOTE: The scope of our project was only to refactor select code. There are no feature additions or changes, so it should work just like production Expertiza.

1) Go to [http://ec2-54-186-80-176.us-west-2.compute.amazonaws.com:3000/ our Expertiza project running on AWS]

2) Login as Admin<br>
'''User:''' user2<br>
'''Password:''' password

3) Click on "Manage..." if you are not automatically directed to the tree display.

=Project Description=

For this project, our team refactored the TreeDisplayController class in the [http://expertiza.ncsu.edu/ Expertiza] OSS project. This class provides access to questionnaires, review rubrics, author feedback, courses, assignments, and course evaluations. The tree display lists all of these categories with the ability for the user to "drill down" into the subcategories or just expand/collapse as needed.

=Refactoring TreeDisplayController Issues=

As part of the refactoring task, we had to resolve the following issues for enhancing code readability and maintainability. The tasks included:

#Similar code found in other locations.
#Cyclomatic and Perceived complexity for get_children_node_ng is too high.
#Useless assignment to variable - `childNodes`.
#Use snake_case for variable names.
#Prefer `each` over `for`.
#The use of `eval` is a serious security risk.
#Avoid the use of the case equality operator `===`.
#Line is too long.
#`end` at 334, 2 is not aligned with `class` at 1, 0.

==1) Similar code found in other locations==

In order to make the code DRY, similar code was moved to a new function, and that was called from the remaining part of the code.

<pre>
  def goto_questionnaires
    node_object = TreeFolder.find_by_name('Questionnaires')
    session[:root] = FolderNode.find_by_node_object_id(node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end

  # direct access to review rubrics
  def goto_review_rubrics
    node_object = TreeFolder.find_by_name('Review')
    session[:root] = FolderNode.find_by_node_object_id(node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end

  # direct access to metareview rubrics
  def goto_metareview_rubrics
    node_object = TreeFolder.find_by_name('Metareview')
    session[:root] = FolderNode.find_by_node_object_id(node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end

  # direct access to teammate review rubrics
  def goto_teammatereview_rubrics
    node_object = TreeFolder.find_by_name('Teammate Review')
    session[:root] = FolderNode.find_by_node_object_id(node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end

  # direct access to author feedbacks
  def goto_author_feedbacks
    node_object = TreeFolder.find_by_name('Author Feedback')
    session[:root] = FolderNode.find_by_node_object_id(node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end
</pre>

Changed to ⇒

<pre>
 def goto_controller(name_parameter)
    node_object = TreeFolder.find_by(name: name_parameter)
    session[:root] = FolderNode.find_by(node_object_id: node_object.id).id
    redirect_to controller: 'tree_display', action: 'list'
  end

  # direct access to questionnaires
  def goto_questionnaires
    goto_controller('Questionnaires')
  end

  # direct access to review rubrics
  def goto_review_rubrics
    goto_controller('Review')
  end

  # direct access to metareview rubrics
  def goto_metareview_rubrics
    goto_controller('Metareview')
  end

  # direct access to teammate review rubrics
  def goto_teammatereview_rubrics
    goto_controller('Teammate Review')
  end
</pre>


==2) Cyclomatic and Perceived complexity for get_children_node_ng is too high==
By creating two separate functions child_nodes_from_params  and initialize_fnode_update_children, the complexity for this function was reduced. The initialize_fnode_update_children function was in-turn sub-functioned into update_fnode_children which updated the children nodes.
The new function looks like this:

<pre>
  def children_node_ng
    child_nodes = child_nodes_from_params(params[:reactParams][:child_nodes])
    tmp_res = {}
    child_nodes.each do |node|
      initialize_fnode_update_children(params, node, tmp_res)
    end
    # res = res_node_for_child(tmp_res)
    res = res_node_for_child(tmp_res)
    respond_to do |format|
      format.html { render json: res }
    end
  end
</pre>

==3) Useless assignment to variable - `childNodes` were removed from following two places.==

<pre>
135 -  childNodes = {}
</pre>

<pre>
222 -  childNodes = {}
</pre>


==4) Use snake_case for variable names.==
Variable names using camelCase were renamed to use snake_case as according to ruby coding guidelines.

Before:
<pre>childNodes = {}
tmpRes
</pre>

After:
<pre>child_nodes = {}
tmp_res
</pre>

==5) Prefer `each` over `for`==
Before:
<pre>
</pre>

After:
<pre>
</pre>


==6)The use of `eval` is a serious security risk.==
eval() executes a string of characters as code. eval() is used in situations where the string contents are not known beforehand or even when the string is generated dynamically. Basically, when eval() is called , it starts a compiler to translate the string. This is detrimental especially when eval() is called on a string submitted by or modifiable by the user. Imagine if the string contains an OS call like rm -rf. But , it is perfectly safe to use eval() on strings , if they are known to be constrained. This problem is analogous to SQL injection.

Before:
<pre>
- for node in childNodes
-      fnode = eval(params[:reactParams][:nodeType]).new
</pre>

After:
<pre>
+  def initialize_fnode_update_children(params, node, tmp_res)
+    fnode = (params[:reactParams][:nodeType]).constantize.new
</pre>

==7) Avoid the use of the case equality operator `===`.==
<pre>
</pre>
has been changed to  ⇒
<pre>
</pre>
==8) Line is too long.==
[[File:8_1_before.png]]

Changed to ==>

[[File:8_1_after.png]]

[[File:8_2_before.png]]

Changed to ==>

[[File:8_2_after.png|upright=1.5]]

=Future Considerations=

=Conclusion=
In conclusion, we were able to successfully refactor the tree_display_controller and related  Rspec tests. We have improved and expanded the use of RESTful and DRY design choices, and overall improved the quality and efficiency of the Expertiza codebase. We have fixed all the issues detected by Code Climate Chrome Extension and refactored the code to make sure it followed good ruby practices and in the end were able to improve the Code Climate score from F to A while not breaking any of the  Rspec tests related.