I am into a PHP to Django migration project, where I cannot change the schema of my Database

There are places where multiple joins are there for fields without FK and I have no rights to add them now. Even on my Django models because of the huge size of the DB and time constraint on the project delivery.

I am using Django-rest-framework and overriding the list method and queryset to accept these raw sqls.

```
sql = """SELECT
  a.field1,
  b.field2
FROM a
LEFT JOIN b ON a.fieldx = b.fieldy"""

```

The problem is I cannot add the fields of the joined table on my serializer class inside the field tuple
because I say model = models.A and this model does not have info about model B.

Your help would be appreciated.

Thank you!

UPDATE
I only use viewset. I am not using any view(is this wrong?)
My Viewset

```
class AdminclassinfoViewSet(viewsets.ModelViewSet): 
    queryset = models.Classroominfo.objects.all()
    serializer_class = ClassroominfoSerializer

    def list(self, request):
       sql = """
         SELECT -- DISTINCT 
           cri.classroomid,
           cri.assessmentid, 
           cri.resourceid,
           al.assessmenttype,
           al.assessmenttitle,
           ri.resourcetype,
           ri.resourcetitle,
           wwi.writtenworktitle,
           cri.writtenworkid, 
           si.firstname,
           si.imageurl,
           date(cri.posteddate) as posteddate,
           cri.studentid
       FROM classroominfo cri
       LEFT OUTER JOIN assignassessmentinfo aai ON aai.assessmentid = cri.assessmentid 
                   AND aai.studentid = cri.studentid 
       LEFT OUTER JOIN assessmentlist al ON al.assessmentid = cri.assessmentid 
       LEFT OUTER JOIN assignresourceinfo ari  ON ari.resourceid = cri.resourceid 
                  AND ari.studentid = cri.studentid 
       LEFT OUTER JOIN resourceinfo ri ON ri.resourceid = cri.resourceid
       LEFT OUTER JOIN assignwrittenworkinfo awwi ON awwi.writtenworkid = cri.writtenworkid
       LEFT OUTER JOIN writtenworkinfo wwi ON wwi.writtenworkid = cri.writtenworkid
       LEFT OUTER JOIN logininfo li ON li.loginid = cri.studentid
       LEFT OUTER JOIN studentinfo si ON si.username = li.username
       WHERE ( ari.isclassroom =1 OR 
             aai.isclassroom =1 OR 
            awwi.isclassroom=1 ) 
       ORDER BY cri.classroomid DESC
       """
       queryset = models.Classroominfo.objects.raw(sql)
       serializer_class = ClassroominfoSerializer
       serializer = ClassroominfoSerializer(queryset, many=True)        
       return Response(serializer.data)

```

My Serializer. I dont know how to refer the joined fields here...

```
class ClassroominfoSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.Classroominfo
        fields = ('classroomid',  'assessmentid','resourceid',
              'writtenworkid')

```