allow merging of examinations

generic/models.py

@@ -1,7 +1,7 @@
 from collections import defaultdict
 import json
 import os
-from typing import Tuple
+from typing import Self, Tuple
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.db import models
 from django.http import HttpRequest
@@ -72,15 +72,66 @@ class Contrast(models.Model):
 
 
 class Examination(models.Model):
+    """
+
+    Currently used for
+    - Atlas series
+    - Longs series
+    - Anatomy questions
+
+    Not used for rapids - yet??
+    """
+
     examination = models.CharField(max_length=200, unique=True)
 
     modality = models.ForeignKey(Modality, on_delete=models.SET_NULL, null=True)
 
+    class Meta:
+        ordering = ("examination",)
+
     def __str__(self):
         return self.examination
 
-    class Meta:
-        ordering = ("examination",)
+    def merge_into(self, examination_to_merge_into: Self, delete: bool=True) -> bool:
+        """Merges the current examination into another
+
+        To do so it replaces all associations (many to many and foreign key relations)
+
+        Returns True if successful
+        """
+        # Get all atlas series with the examination
+        atlas_series = self.atlas_series_examination.all()
+        longs_series = self.series_examination.all()
+        anatomy_questions = self.anatomyquestion_set.all()
+
+        # Reassign them to the new object
+        for series in atlas_series:
+            series.examination = examination_to_merge_into
+            series.save()
+
+        for series in longs_series:
+            series.examination = examination_to_merge_into
+            series.save()
+
+        for question in anatomy_questions:
+            question.examination = examination_to_merge_into
+            question.save()
+
+        # quick check to make sure nothing has gone wrong and we have hanging
+        # associations
+        querysets = (
+            self.atlas_series_examination.all(),
+            self.series_examination.all(),
+            self.anatomyquestion_set.all(),
+        )
+
+        for q in querysets:
+            if q.count() > 0:
+                return False
+
+        if delete:
+            self.delete()
+        return True
 
 
 class Site(models.Model):