/NestedFolders

Primary LanguageJavaScript

Frame_Kandel

Setup

To run the project locally, you'll need to take the following steps:

  • Clone this repo!
  • npm install, or yarn install
  • Create two postgres databases: Frame_Kandel and Frame_Kandel-test
    • If there are Postgres authentication issues see the note in /server/db/db.js
  • Run yarn seed to:
    • Create the tables from our schema
    • Populate two Projects you can explore with the API
  • Run yarn start to start the app
    • Navigate to the following:
      • localhost:3000/api/projects/1
      • localhost:3000/api/projects/2
    • You can display child folders as a list by adding ?flatten=true to the URL
  • Run yarn test to run a test of the API with mocha

Alternatively, you can head to the deployed site

How Querying Works

Nested queries are handled by the sequelize-hierarchy plugin. When a call to the folder hierarchical structure is made the generated SQL looks like:

SELECT projects.id,
       projects.name,
       projects.root_folder_id,
       folders.id,
       folders.name,
       folders.parent_folder_id,
       folders."hierarchyLevel",
       descendent.id,
       descendent.name,
       descendent.parent_folder_id,
       descendent."hierarchyLevel",
       ancestor."foldersId",
       ancestor."ancestorId"
FROM projects AS projects
LEFT OUTER JOIN folders ON projects.root_folder_id = folders.id
LEFT OUTER JOIN (foldersancestors AS ancestor
                 INNER JOIN folders AS descendent ON descendent.id = ancestor."foldersId") ON folders.id = ancestor."ancestorId"
WHERE projects.id = '1'

This queries utilizes a through table to rapidly identify all the children of the requested root folder. The plugin then utilizes an afterFind hook to build the nested structure from the return data. If a consumer of this API does not want to see the descendent nesting, passing flatten=true in the request query will simply return the result of the query above.