Add ContentNodeMetadata model and API viewset

[bjester]

Parent: #3808
Depends: #3927, #3929

Desired behavior

Add a new model ContentNodeMetadata to the kolibri_public app

• It should inherit ContentNode from the existing kolibri_content app
• It should nominally implement the same additional fields as ContentNode from kolibri/content
• The lang field should be overridden and made a FK to the core Language model
• The license field should be overridden and made a FK to the core License model

Add a new ContentNodeMetadataViewset similar to Kolibri's which returns a JSON response

• It should only accept read-only GET method requests
• /kolibri/api/public/v2/contentnode/ should require at least one filter and return matching content nodes
• /kolibri/api/public/v2/contentnode/<contentnode_id> should return info for the requested contentnode
• It should use cursor based pagination for list responses, utilizing a max_results param defaulting to 25 (set an absolute maximum of 100)
• It should support the same filtering params that Kolibri does
• It should annotate associated files, language, and assessment metadata in the response if applicable (see response examples below)
• It should annotate any available fields as True
• It should make all storage URLs absolute for files or thumbnails (for example https://studio.learningequality.org/content/ or https://hotfixes.studio.learningequality.org/content/ etc. depending on the environment)
• It should have a Cache-control response header with value public, stale-while-revalidate=100, max-age=300
• It should add a Last-modified response header which is equal to the greatest last_updated of the channel(s) in the response
• It should accept a If-modified-since request header and should minimally filter the request and return a 304 Not modified response if no associated channels in the response have a last_updated that is greater (see conditional processing)
• It should not return any Set-cookie headers in the response

Example response: contentnode metadata

{
  "id": "cf1de634e5855069bcb135e3b6ae3545",
  "author": "",
  "available": true,
  "channel_id": "c1f2b7e6ac9f56a2bb44fa7a48b66dce",
  "coach_content": false,
  "content_id": "965bc8aa4ab75776a5a02a47f6ad8012",
  "description": "Una tabla de tallos y hojas se utiliza para mostrar datos. El 'tallo' a la izquierda muestra el primer dígito o dígitos. La 'hoja' a la derecha muestra el último dígito. Por ejemplo, 543 y 548 pueden mostrarse juntos como tallo y hoja así: 54 | 3,8.",
  "kind": "video",
  "license_description": "",
  "license_name": "CC BY-NC-SA",
  "license_owner": "Khan Academy",
  "num_coach_contents": 0,
  "options": {},
  "parent": "521113d0522d50e38fadfd6bfa29f3f4",
  "sort_order": 1,
  "title": "Los diagramas de tallo y hoja",
  "lft": 1998,
  "rght": 1999,
  "tree_id": 8,
  "learning_activities": [
    "UD5UGM0z"
  ],
  "grade_levels": [
    "BkGYi3lD"
  ],
  "resource_types": [],
  "accessibility_labels": [],
  "categories": [
    "d&WXdXWF.qs0Xlaxq.0t5msbL5"
  ],
  "duration": null,
  "ancestors": [
    {
      "id": "c1f2b7e6ac9f56a2bb44fa7a48b66dce",
      "title": "Khan Academy (Español)"
    },
    {
      "id": "5edd6eae85eb55f097cd218e45a66e8c",
      "title": "Matemáticas"
    },
    {
      "id": "cde5a643de405d07b9b04a18bc9db451",
      "title": "Preálgebra"
    },
    {
      "id": "0bb4444aa1905746a0fc193adacffdf1",
      "title": "Leer e interpretar datos"
    },
    {
      "id": "521113d0522d50e38fadfd6bfa29f3f4",
      "title": "Diagramas de tallos y hojas"
    }
  ],
  "assessmentmetadata": {...},
  "tags": ["tag1", "tag2"],
  "files": [...],
  "thumbnail": "https://studio.learningequality.org/content/storage/d/5/d521574b567a6054146e0351a293e559.png",
  "lang": {...},
  "is_leaf": true
}

Example response: contentnode.lang

{
    "id": "en",
    "lang_code": "en",
    "lang_subcode": null,
    "lang_name": "English",
    "lang_direction": "ltr"
}

Example response: contentnode.files[]

{
  "id": "aeb5b9cb1bb441b18a6aa305871d7836",
  "priority": 2,
  "preset": "low_res_video",
  "supplementary": false,
  "thumbnail": false,
  "lang": null,
  "checksum": "00fbaef027e5e3a7b27be50bf015cc3c",
  "available": true,
  "file_size": 2812691,
  "extension": "mp4",
  "storage_url": "https://studio.learningequality.org/content/storage/0/0/00fbaef027e5e3a7b27be50bf015cc3c.mp4"
}

Example response: contentnode.assessmentmetadata

{
    "assessment_item_ids": [
        "6006a858fd8c542788dc246a21d5df1a",
        "f19614187215539d804930300fd26ee2",
        "8e8c635433b95f62944725b9de1d3ca0",
        "8ec86ffaecc253c3b9346ae26aa3ada4"
    ],
    "number_of_assessments": 24,
    "mastery_model": {
        "type": "m_of_n",
        "n": 4,
        "m": 3
    },
    "randomize": true,
    "is_manipulable": true,
    "contentnode": "b6f8e89954665ac8bb01d92dc4bba95c"
}

Current behavior

These do not exist currently on Studio

Value add

This model and API will support remote content browsing on Studio

[bjester]

Also, ensure that there isn't a Set-cookie header in the response https://developers.cloudflare.com/cache/about/default-cache-behavior/

[rtibbles]

Fixed in #3955