fix semester deletion

src/api/app.py

@@ -27,11 +27,9 @@
 import pandas as pd
 from constants import Constants
 
-"""
-NOTE: on caching
-on add of semester of change of data from GET
-do a cache.clear() to ensure data integrity
-"""
+# NOTE: on caching
+# on add of semester of change of data from GET
+# do a cache.clear() to ensure data integrity
 
 app = FastAPI()
 app.add_middleware(SessionMiddleware,
@@ -46,7 +44,7 @@
 date_range_map = DateMapping.semester_date_mapping(db_conn)
 admin_info = AdminInfo.Admin(db_conn)
 course_select = CourseSelect.student_course_selection(db_conn)
-semester_info = SemesterInfo.semester_info(db_conn)
+semester_info = SemesterInfo.semester_info(db_conn, FastAPICache)
 professor_info = All_professors.Professor(db_conn, FastAPICache)
 users = UserModel.User()
 
@@ -143,9 +141,8 @@ def set_defaultSemester(semester_set: DefaultSemesterSetPydantic):
     success, error = admin_info.set_semester_default(semester_set.default)
     if success:
         return Response(status_code=200)
-    else:
-        print(error)
-        return Response(error.__str__(), status_code=500)
+    print(error)
+    return Response(error.__str__(), status_code=500)
 
 #Parses the data from the .csv data files
 @app.post('/api/bulkCourseUpload')
@@ -176,9 +173,8 @@ async def uploadHandler(
     isSuccess, error = courses.populate_from_csv(csv_file)
     if (isSuccess):
         return Response(status_code=200)
-    else:
-        print(error)
-        return Response(error.__str__(), status_code=500)
+    print(error)
+    return Response(error.__str__(), status_code=500)
 
 @app.post('/api/bulkProfessorUpload')
 async def uploadJSON(
@@ -208,11 +204,15 @@ async def uploadJSON(
     if isSuccess:
         print("SUCCESS")
         return Response(status_code=200)
-    else:
-        print("NOT WORKING")
-        print(error)
-        return Response(error.__str__(), status_code=500)
+    print("NOT WORKING")
+    print(error)
+    return Response(error.__str__(), status_code=500)
 
+@app.delete('/api/semester/{semester_id}')
+async def remove_semester(semester_id: str):
+    print(semester_id)
+    semester, error = semester_info.delete_semester(semester=semester_id)
+    return Response(status_code=200) if not error else Response(str(error), status_code=500)
 
 @app.post('/api/mapDateRangeToSemesterPart')
 async def map_date_range_to_semester_part_handler(request: Request):
@@ -234,8 +234,7 @@ async def map_date_range_to_semester_part_handler(request: Request):
              semester_info.upsert(semester_title, is_publicly_visible)
              if (not error):
                  return Response(status_code=200)
-             else:
-                 return Response(error, status_code=500)
+             return Response(error, status_code=500)
      return Response("Did not receive proper form data", status_code=500)
 
 @app.get('/api/user/course')

src/api/db/admin.py

@@ -5,7 +5,7 @@ def __init__(self, db_conn):
 		self.interface_name = 'admin_info'
 
 	def get_semester_default(self):
-		# NOTE: COALESCE takes first non-null vaue from the list
+		# NOTE: COALESCE takes first non-null value from the list
 		result, error = self.db_conn.execute("""
 			SELECT admin.semester FROM admin_settings admin
 			UNION ALL
@@ -21,8 +21,7 @@ def get_semester_default(self):
 
 		if error:
 			return (None, error)
-		else:
-			return (default_semester, error)
+		return (default_semester, error)
 
 	def set_semester_default(self, semester):
 		try:
@@ -40,5 +39,4 @@ def set_semester_default(self, semester):
 
 		if response != None:
 			return(True, None)
-		else:
-			return (False, error)
+		return (False, error)

src/api/db/semester_info.py

@@ -1,7 +1,20 @@
-class semester_info:
+import asyncio
 
-    def __init__(self, db_wrapper):
+class semester_info:
+    def __init__(self, db_wrapper, cache):
         self.db = db_wrapper
+        self.cache = cache
+
+    def clear_cache(self):
+        try:
+            loop = asyncio.get_running_loop()
+        except RuntimeError:
+            loop = None
+
+        if loop and loop.is_running():
+            loop.create_task(self.cache.clear(namespace="API_CACHE"))
+        else:
+            asyncio.run(self.cache.clear("API_CACHE"))
 
     def upsert(self, semester, isPublic):
         self.db.execute("""
@@ -28,3 +41,15 @@ def is_public(self, semester):
         if data is not None and len(data) > 0:
             return data[0]['public']
         return False
+
+    def delete_semester(self, semester):
+        # clear cache so this semester does not come up again
+        self.clear_cache()
+        return self.db.execute("""
+            BEGIN TRANSACTION;
+                DELETE FROM semester_info
+                WHERE semester=%(Semester)s;
+            COMMIT;
+        """, {
+            "Semester": semester
+        }, isSELECT=False)

src/api/tables/course.py

@@ -1,4 +1,5 @@
-from sqlalchemy import Column
+from sqlalchemy import Column, ForeignKey
+from sqlalchemy.orm import relationship, backref
 from sqlalchemy.dialects.postgresql import TEXT, INTEGER, VARCHAR, DATE, TSVECTOR
 
 from .database import Base
@@ -8,7 +9,10 @@ class Course(Base):
 
     crn = Column(VARCHAR(length=255), primary_key=True)
     section = Column(VARCHAR(length=255))
-    semester = Column(VARCHAR(length=255))
+
+    semester = Column(VARCHAR(length=255), ForeignKey("semester_info.semester", ondelete="CASCADE"))
+    professor = Column(VARCHAR(length=255))    
+
     min_credits = Column(INTEGER)
     max_credits = Column(INTEGER)
     date_start = Column(DATE)

src/api/tables/semester_info.py

@@ -1,4 +1,5 @@
 from sqlalchemy import Column, PrimaryKeyConstraint
+from sqlalchemy.orm import relationship
 from sqlalchemy.dialects.postgresql import VARCHAR, BOOLEAN
 
 from .database import Base
@@ -8,3 +9,5 @@ class SemesterInfo(Base):
 
     semester = Column(VARCHAR(length=255), primary_key=True)
     public = Column(BOOLEAN)
+
+    courses = relationship("Course", backref="semester_info", passive_deletes=True)