Ticket #9779: 9779-fk-introspection-for-sqlite.diff

django/db/backends/sqlite3/introspection.py

@@ -55 +55 @@
                  info['null_ok']) for info in self._table_info(cursor, table_name)]
 
     def get_relations(self, cursor, table_name):
-        raise NotImplementedError
+        """
+        Returns a dictionary of {field_index: (field_index_other_table, other_table)}
+        representing all relationships to the given table. Indexes are 0-based.
+        """
+        
+        import re
+        
+        # Dictionary of relations to return
+        relations = {}
+        
+        # Schema for this table
+        cursor.execute("select sql from sqlite_master where tbl_name='%s'" % table_name)
+        results = cursor.fetchone()[0].strip()
+        results = results.split('(', 1)[1]
+        results = results.rsplit(')', 1)[0]
+
+        # walk through and look for references to other tables.
+        for index, i in enumerate(results.split(',')):
+            i = i.strip()
+            if i.startswith("UNIQUE"):
+                continue
+
+            m = re.search('references (.*) \(["|](.*)["|]\)', i, re.I)
+            
+            if not m:
+                continue
+        
+            table, column = m.groups()
+            
+            table = table.strip('"')
+            column = column.strip('"')
+            
+            cursor.execute("select sql from sqlite_master where tbl_name='%s'" % table)
+            
+            other_table_results = cursor.fetchone()[0].strip()
+            other_table_results = other_table_results.split('(', 1)[1]
+            other_table_results = other_table_results.rsplit(')', 1)[0]
+            
+            second_index = None
+            for _index, j in enumerate(other_table_results.split(',')):
+                j = j.strip()
+                if j.startswith('UNIQUE'):
+                    continue
+
+                name = j.split(' ', 1)[0].strip('"')
+                if name == column:
+                    second_index = _index
+            
+            if second_index != None:
+                relations[index] = (second_index, table)
+                            
+        return relations
 
     def get_indexes(self, cursor, table_name):
         """