Allow iterables other than lists in m2m records (#189)

* Allow iterables other than Lists in m2m records
* Add test for iterable m2m records

Thanks, @adamwolf!

sqlite_utils/db.py

@@ -1,5 +1,6 @@
 from .utils import sqlite3, OperationalError, suggest_column_types, column_affinity
 from collections import namedtuple, OrderedDict
+from collections.abc import Mapping
 import contextlib
 import datetime
 import decimal
@@ -1772,15 +1773,15 @@ class Table(Queryable):
             return pk
 
     def m2m(
-        self, other_table, record_or_list=None, pk=DEFAULT, lookup=None, m2m_table=None
+        self, other_table, record_or_iterable=None, pk=DEFAULT, lookup=None, m2m_table=None
     ):
         if isinstance(other_table, str):
             other_table = self.db.table(other_table, pk=pk)
         our_id = self.last_pk
         if lookup is not None:
-            assert record_or_list is None, "Provide lookup= or record, not both"
+            assert record_or_iterable is None, "Provide lookup= or record, not both"
         else:
-            assert record_or_list is not None, "Provide lookup= or record, not both"
+            assert record_or_iterable is not None, "Provide lookup= or record, not both"
         tables = list(sorted([self.name, other_table.name]))
         columns = ["{}_id".format(t) for t in tables]
         if m2m_table is not None:
@@ -1801,10 +1802,11 @@ class Table(Queryable):
                 m2m_table_name = m2m_table or "{}_{}".format(*tables)
         m2m_table = self.db.table(m2m_table_name, pk=columns, foreign_keys=columns)
         if lookup is None:
+            # if records is only one record, put the record in a list
             records = (
-                [record_or_list]
+                [record_or_iterable]
-                if not isinstance(record_or_list, (list, tuple))
+                if isinstance(record_or_iterable, Mapping)
-                else record_or_list
+                else record_or_iterable
             )
             # Ensure each record exists in other table
             for record in records:

tests/test_m2m.py

@@ -43,6 +43,42 @@ def test_insert_m2m_list(fresh_db):
            ] == dogs_humans.foreign_keys
 
 
+def test_insert_m2m_iterable(fresh_db):
+    iterable_records = ({"id": 1, "name": "Phineas"}, {"id": 2, "name": "Ferb"})
+
+    def iterable():
+        for record in iterable_records:
+            yield record
+
+    platypuses = fresh_db["platypuses"]
+    platypuses.insert({"id": 1, "name": "Perry"}, pk="id").m2m(
+        "humans",
+        iterable(),
+        pk="id",
+    )
+
+    assert {"platypuses", "humans", "humans_platypuses"} == set(fresh_db.table_names())
+    humans = fresh_db["humans"]
+    humans_platypuses = fresh_db["humans_platypuses"]
+    assert [{"humans_id": 1, "platypuses_id": 1}, {"humans_id": 2, "platypuses_id": 1}] == list(
+        humans_platypuses.rows
+    )
+    assert [{"id": 1, "name": "Phineas"}, {"id": 2, "name": "Ferb"}] == list(
+        humans.rows
+    )
+    assert [
+               ForeignKey(
+                   table="humans_platypuses", column="platypuses_id", other_table="platypuses", other_column="id"
+               ),
+               ForeignKey(
+                   table="humans_platypuses",
+                   column="humans_id",
+                   other_table="humans",
+                   other_column="id",
+               ),
+           ] == humans_platypuses.foreign_keys
+
+
 def test_m2m_with_table_objects(fresh_db):
     dogs = fresh_db.table("dogs", pk="id")
     humans = fresh_db.table("humans", pk="id")