Proposal: Flatten/Standardize ContentType Decorator's Object Shape #539

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1. MKwenhua

   added

   in progress

   on Nov 15, 2017
2. MKwenhua commented on Mar 6, 2018

   

   MKwenhua

   on Mar 6, 2018

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   Final Comments

   So it seems that I have sort of covered why deeply nested objects can throw but below I would like to explain each of the main reasons why this can cause problems as well as a potential remedy in case nesting is absolutely necessary.

   Why Nesting Can Lead To Issues:

   • Unknown Traversals And Implicit Dependencies complicates data access and reduces flexibility.
   • Propensity Towards Data Loss: This one trips me up a lot and is a mild nuisance when writing reducers.
   • Prevents Good Abstractions: When each FieldTypes data is organized differently components need to be custom made and can't be modified.

   Unknown Traversals And Implicit Dependencies

   So lets say that each fields metadata is randomly created with different nested values. What this means is that each field cell/component when being rendered needs to consider what the object's shape is. Because of these different nested states a implicit dependency is created between how the data is stored in the database and how the data is accessed within both Rails Cells or React.

   An issue that arises when data is nested is that any change or removal of a nested key runs a risk of accessing a property on a null or undefined property. This issue can be avoided however when using flat 1D objects because accessing a nonexistent key on an object will not throw an exception. Additionally with ESNext completely flat objects can be treated as separate objects using the rest operator:

   const metadata = { 
     render_method: "wysiwyg",
     field_id: "8a810-72726hnva-jhvjssdcs",
     style:  {borderRadius: "8px"}, 
     src: 'an_image_url',
     id: "blog_body_editor",
     data-gtm: "7828734687346834"
   }
   
   //now just pull out the non attribute keys as such:
   const { render_method, field_id, ...attrs } = metadata;

   Propensity Towards Data Loss

   In Redux every dispatch generates and creates a new object created from state. Often times when working with nested objects, devs accidentally replace the object with just the changes. For example:

   const TheState = {
       connected: true,
       user_profile: {
          friends: 6,
          name: 'Richard Feynman',
          sandwich_type:  'Pastrami'
       }
   }
   
   //Now within the reducer for action NEW_FRIEND_ADDED
   
   {
   . . .
   case NEW_FRIEND_ADDED: {
       return {
          ...state,
          user_profile: {
             friends: state.user_profile.friends + 1
          }
       }
   }
   . . .
   }

   This error would result in the new state being:

   const TheState = {
       connected: true,
       user_profile: {
          friends: 7
       }
   }

   But this can be fixed by doing a spread of the rest of the object:

   {
   . . .
   case NEW_FRIEND_ADDED: {
       return {
          ...state,
          user_profile: {
             ...state.user_profile,
             friends: state.user_profile.friends + 1
          }
       }
   }
   . . .
   }

   So as you can see the deeper you nest the more unwieldily it gets.

   Prevents Good Abstractions

   If data is flattened abstractions below can be built to make rendering much easier. For example lets assume we have an array of field types:

      Step.FormFields.map((field, i) => {
         const {render_method, field_id, ...data} = field.metadata;
        return FieldTypeRendMethods[field.type][render_method](data)
       })
3. MKwenhua commented on Mar 6, 2018

   

   MKwenhua

   on Mar 6, 2018

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   @toastercup I will add some more comments when I get home tonight, so just wait till tomorrow morning before taking me off the contributor list. I need to pack up my things
4. toastercup commented on Mar 6, 2018

   

   toastercup

   on Mar 6, 2018

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   @MKwenhua take your time - I don't have to take you off contrib right away