Discovery: store and return Scratch data (#720)

## Status

- Closes
https://github.com/orgs/RaspberryPiFoundation/projects/51/views/11?pane=issue&itemId=154102194&issue=RaspberryPiFoundation%7Cdigital-editor-issues%7C1130
- Related to
RaspberryPiFoundation/editor-standalone#749

## Points for consideration:

See [the
ADR](https://github.com/RaspberryPiFoundation/documentation/blob/e1d78cf16af5bd97fe46194750b48c89806eec0c/docs/technology/codebases-and-products/editor/adrs/011-scratch-project-storage.md)
for performance and security implications.

## What's changed?

- Enables creation, saving and loading of Scratch project files
(`project.json`). Does not yet enable these for assets.

Author: mwtrew

app/controllers/api/lessons_controller.rb

@@ -114,7 +114,8 @@ def base_params
             :name,
             :project_type,
             :locale,
-            { components: %i[id name extension content index default] }
+            { components: %i[id name extension content index default] },
+            { scratch_component: {} }
           ]
         }
       )

app/controllers/api/projects_controller.rb

@@ -117,6 +117,7 @@ def base_params
         {
           components: %i[id name extension content index default]
         },
+        scratch_component: {},
         parent: {},
         image_list: []
       )

app/controllers/api/scratch/projects_controller.rb

@@ -5,12 +5,16 @@ module Scratch
     class ProjectsController < ScratchController
       skip_before_action :authorize_user, only: [:show]
       skip_before_action :check_scratch_feature, only: [:show]
+      before_action :load_project, only: %i[show update]
 
       def show
-        render :show, formats: [:json]
+        render json: @project.scratch_component.content
       end
 
       def update
+        scratch_content = params.permit!.slice(:meta, :targets, :monitors, :extensions)
+        @project.scratch_component&.content = scratch_content.to_unsafe_h
+        @project.save!
         render json: { status: 'ok' }, status: :ok
       end
     end

app/controllers/api/scratch/scratch_controller.rb

@@ -16,6 +16,11 @@ def check_scratch_feature
 
         raise ActiveRecord::RecordNotFound, 'Not Found'
       end
+
+      def load_project
+        project_loader = ProjectLoader.new(params[:id], [params[:locale]])
+        @project = project_loader.load
+      end
     end
   end
 end

app/graphql/mutations/create_project.rb

@@ -10,7 +10,8 @@ class CreateProject < BaseMutation
     def resolve(**input)
       project_hash = input.merge(
         user_id: context[:current_user]&.id,
-        components: input[:components]&.map(&:to_h)
+        components: input[:components]&.map(&:to_h),
+        scratch_component: input[:scratch_component]&.to_h
       )
 
       response = Project::Create.call(project_hash:, current_user: context[:current_user])

app/models/project.rb

@@ -13,13 +13,15 @@ module Types
   belongs_to :parent, optional: true, class_name: :Project, foreign_key: :remixed_from_id, inverse_of: :remixes
   has_many :remixes, dependent: :nullify, class_name: :Project, foreign_key: :remixed_from_id, inverse_of: :parent
   has_many :components, -> { order(default: :desc, name: :asc) }, dependent: :destroy, inverse_of: :project
+  has_one :scratch_component, dependent: :destroy, inverse_of: :project, required: false
   has_many :project_errors, dependent: :nullify
   has_many_attached :images
   has_many_attached :videos
   has_many_attached :audio
   has_one :school_project, dependent: :destroy
 
   accepts_nested_attributes_for :components
+  accepts_nested_attributes_for :scratch_component
 
   before_validation :check_unique_not_null, on: :create
   before_validation :create_school_project_if_needed
@@ -67,6 +69,10 @@ def components=(array)
     super(array.map { |o| o.is_a?(Hash) ? Component.new(o) : o })
   end
 
+  def scratch_component=(value)
+    super(value.is_a?(Hash) ? ScratchComponent.new(value) : value)
+  end
+
   def last_edited_at
     # datetime that the project or one of its components was last updated
     [updated_at, components.maximum(:updated_at)].compact.max

app/models/scratch_component.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class ScratchComponent < ApplicationRecord
+  belongs_to :project
+end

db/migrate/20260309104851_create_scratch_components.rb

@@ -0,0 +1,10 @@
+class CreateScratchComponents < ActiveRecord::Migration[7.2]
+  def change
+    create_table :scratch_components, id: :uuid do |t|
+      t.jsonb :content
+      t.references :project, null: false, foreign_key: true, type: :uuid, index: { unique: true }
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -18,8 +18,9 @@ def call(project_hash:, current_user:)
 
       def build_project(project_hash, current_user)
         project_hash[:identifier] = PhraseIdentifier.generate unless current_user&.experience_cs_admin?
-        new_project = Project.new(project_hash.except(:components))
+        new_project = Project.new(project_hash.except(:components, :scratch_component))
         new_project.components.build(project_hash[:components])
+        new_project.build_scratch_component(project_hash[:scratch_component]) if project_hash[:scratch_component].present?
         new_project
       end
     end