- try:
- session.add(row)
- session.flush()
- except IntegrityError as e:
- failed_rows.append(row)
-
- # Loop over the failed rows and keep trying to insert them. If a loop
- # doesn't manage to insert any rows, bail.
- do_another_loop = True
- while failed_rows and do_another_loop:
- do_another_loop = False
-
- for i, row in enumerate(failed_rows):
- try:
- session.add(row)
- session.flush()
-
- # Success!
- del failed_rows[i]
- do_another_loop = True
- except IntegrityError as e:
- pass
-
- if failed_rows:
- print len(failed_rows), "rows failed"
- else:
- print 'loaded'
+ # May need to stash this row and add it later if it refers to a
+ # later row in this table
+ if self_ref_columns:
+ foreign_ids = [getattr(row, _.name) for _ in self_ref_columns]
+ foreign_ids = [_ for _ in foreign_ids if _] # remove NULL ids
+
+ if not foreign_ids:
+ # NULL key. Remember this row and add as usual.
+ seen_ids[row.id] = 1
+
+ elif all(_ in seen_ids for _ in foreign_ids):
+ # Non-NULL key we've already seen. Remember it and commit
+ # so we know the old row exists when we add the new one
+ session.commit()
+ seen_ids[row.id] = 1
+
+ else:
+ # Non-NULL future id. Save this and insert it later!
+ deferred_rows.append((row, foreign_ids))
+ continue
+
+ session.add(row)
+
+ session.commit()
+
+ # Attempt to add any spare rows we've collected
+ for row, foreign_ids in deferred_rows:
+ if not all(_ in seen_ids for _ in foreign_ids):
+ # Could happen if row A refers to B which refers to C.
+ # This is ridiculous and doesn't happen in my data so far
+ raise ValueError("Too many levels of self-reference! "
+ "Row was: " + str(row.__dict__))
+
+ session.add(row)
+ seen_ids[row.id] = 1
+ session.commit()
+
+ print 'loaded'