Simplify drop-foreign-key, and drop_foreign_keys, closes #177

docs/cli.rst

@@ -592,7 +592,7 @@ Every option for this table (with the exception of ``--pk-none``) can be specifi
 ``--default-none column``
     Remove the default value for this column.
 
-``--drop-foreign-key col other_table other_column``
+``--drop-foreign-key column``
     Drop the specified foreign key.
 
 If you want to see the SQL that will be executed to make the change without actually executing it, add the ``--sql`` flag. For example::

docs/python-api.rst

@@ -995,17 +995,14 @@ The ``column_order=`` parameter can be used to change the order of the columns.
     # Change column order
     table.transform(column_order=("name", "age", "id")
 
-You can use ``.transform()`` to remove foreign key constraints from a table. You will need to know the name of the column, the name of the table it points to and the name of the column it references on that other table.
+You can use ``.transform()`` to remove foreign key constraints from a table.
 
 This example drops two foreign keys - the one from ``places.country`` to ``country.id`` and the one from ``places.continent`` to ``continent.id``:
 
 .. code-block:: python
 
     db["places"].transform(
-        drop_foreign_keys=(
-            ("country", "country", "id"),
-            ("continent", "continent", "id"),
-        )
+        drop_foreign_keys=("country", "continent")
     )
 
 .. _python_api_transform_sql:

sqlite_utils/cli.py

@@ -924,7 +924,7 @@ def rows(ctx, path, dbtable, nl, arrays, csv, no_headers, table, fmt, json_cols)
 )
 @click.option(
     "--drop-foreign-key",
-    type=(str, str, str),
+    type=str,
     multiple=True,
     help="Drop this foreign key constraint",
 )

sqlite_utils/db.py

@@ -835,9 +835,7 @@ def transform_sql(
         # foreign_keys
         create_table_foreign_keys = []
         for table, column, other_table, other_column in self.foreign_keys:
-            if (drop_foreign_keys is None) or (
-                (column, other_table, other_column) not in drop_foreign_keys
-            ):
+            if (drop_foreign_keys is None) or (column not in drop_foreign_keys):
                 create_table_foreign_keys.append(
                     (rename.get(column) or column, other_table, other_column)
                 )

tests/test_cli.py

@@ -1542,8 +1542,6 @@ def test_transform_drop_foreign_key(db_path):
             "places",
             "--drop-foreign-key",
             "country",
-            "country",
-            "id",
         ],
     )
     print(result.output)

tests/test_transform.py

@@ -274,12 +274,7 @@ def test_transform_drop_foreign_keys(fresh_db, use_pragma_foreign_keys):
         ),
     ]
     # Drop two of those foreign keys
-    fresh_db["places"].transform(
-        drop_foreign_keys=(
-            ("country", "country", "id"),
-            ("continent", "continent", "id"),
-        )
-    )
+    fresh_db["places"].transform(drop_foreign_keys=("country", "continent"))
     # Should be only one foreign key now
     assert fresh_db["places"].foreign_keys == [
         ForeignKey(table="places", column="city", other_table="city", other_column="id")