vbv/server/vbv_lernwelt/course/middleware.py

# myapp/middleware.py
import json
import re

import structlog
from django.core.cache import cache

logger = structlog.get_logger(__name__)

# TODO: refactor so that the query from the client is loaded
COURSE_QUERY = """
query courseQuery($slug: String!, $user: String) {
  course(slug: $slug) {
    id
    title
    slug
    category_name
    profiles
    course_session_users(id: $user) {
      id
      __typename
      chosen_profile
      course_session {
        id
        __typename
      }
    }
    configuration {
      id
      enable_circle_documents
      enable_learning_mentor
      enable_competence_certificates
      is_uk
      is_vv
      __typename
    }
    action_competences {
      competence_id
      ...CoursePageFields
      performance_criteria {
        competence_id
        learning_unit {
          id
          slug
          evaluate_url
          __typename
        }
        ...CoursePageFields
        __typename
      }
      __typename
    }
    learning_path {
      ...CoursePageFields
      topics {
        is_visible
        ...CoursePageFields
        circles {
          description
          goals
          profiles
          is_base_circle
          ...CoursePageFields
          learning_sequences {
            icon
            ...CoursePageFields
            learning_units {
              evaluate_url
              ...CoursePageFields
              performance_criteria {
                ...CoursePageFields
                __typename
              }
              learning_contents {
                can_user_self_toggle_course_completion
                content_url
                minutes
                description
                ...CoursePageFields
                ... on LearningContentAssignmentObjectType {
                  assignment_type
                  content_assignment {
                    id
                    assignment_type
                    __typename
                  }
                  competence_certificate {
                    ...CoursePageFields
                    __typename
                  }
                  __typename
                }
                ... on LearningContentEdoniqTestObjectType {
                  checkbox_text
                  has_extended_time_test
                  content_assignment {
                    id
                    assignment_type
                    __typename
                  }
                  competence_certificate {
                    ...CoursePageFields
                    __typename
                  }
                  __typename
                }
                ... on LearningContentRichTextObjectType {
                  text
                  __typename
                }
                __typename
              }
              __typename
            }
            __typename
          }
          __typename
        }
        __typename
      }
      __typename
    }
    __typename
  }
}
fragment CoursePageFields on CoursePageInterface {
  title
  id
  slug
  content_type
  frontend_url
  __typename
}
"""

COURSE_SESSION_USER_QUERY = """
query courseQuery($slug: String!, $user: String) {
  course(slug: $slug) {
    course_session_users(id: $user) {
      id
      __typename
      chosen_profile
      course_session {
        id
        __typename
      }
    }
  }
}
"""


class GraphQLQueryFilterMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        # Check if the request is a GraphQL request
        if request.content_type == "application/json" and "/graphql" in request.path:
            try:
                # Parse the GraphQL query from the request body
                body = json.loads(request.body)
                query = body.get("query", "")

                if self.normalize_string(query) == self.normalize_string(COURSE_QUERY):
                    logger.debug("CourseQuery detected")
                    slug = body.get("variables", {}).get("slug", "")

                    if slug:
                        key = f"course_query_{slug}"
                        cache_data = cache.get(key)

                        if cache_data:
                            # Cache hit: only make course session user query and add to cache data
                            logger.debug("cache hit", key=key)
                            body["query"] = COURSE_SESSION_USER_QUERY
                            request._body = json.dumps(body).encode("utf-8")
                            response = self.get_response(request)
                            content = json.loads(response.content)
                            cache_data["data"]["course"]["course_session_users"] = (
                                content["data"]["course"]["course_session_users"]
                            )
                            response.content = json.dumps(cache_data)
                            return response

                        else:
                            # Cache miss: make the original query and cache the result
                            logger.debug("cache miss", key=key)
                            response = self.get_response(request)
                            content = json.loads(response.content)
                            del content["data"]["course"]["course_session_users"]
                            cache.set(key, content, 60 * 10)

                            return response
            except Exception as e:
                # Handle any exceptions in parsing or filtering
                logger.error("Error in GraphQLQueryFilterMiddleware", exc_info=e)

        # Continue processing the request if not blocked
        response = self.get_response(request)
        return response

    def normalize_string(self, s):
        # Remove all whitespace characters (space, tabs, newlines)
        return re.sub(r"\s+", "", s)