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Docs for .transform() add_foreign_keys= and foreign_keys=, refs #577

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Plus extended tests to cover the more explicit definitions.
This commit is contained in:
Simon Willison 2023-08-17 17:38:43 -07:00
commit 19c1640876
2 changed files with 59 additions and 6 deletions
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33
docs/python-api.rst
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@ -1467,6 +1467,39 @@ The ``column_order=`` parameter can be used to change the order of the columns.
# Change column order
table.transform(column_order=("name", "age", "id")
Adding foreign key constraints
------------------------------
You can add one or more foreign key constraints to a table using the ``add_foreign_keys=`` parameter:
.. code-block:: python
db["places"].transform(
add_foreign_keys=(
("country", "country", "id"),
("continent", "continent", "id")
)
)
This accepts the same arguments described in :ref:`specifying foreign keys <python_api_foreign_keys>` - so you can specify them as a full tuple of ``(column, other_table, other_column)``, or you can take a shortcut and pass just the name of the column, provided the table can be automatically derived from the column name:
.. code-block:: python
db["places"].transform(
add_foreign_keys=(("country", "continent"))
)
Replacing foreign key constraints
---------------------------------
The ``foreign_keys=`` parameter is similar to to ``add_foreign_keys=`` but can be be used to replace all foreign key constraints on a table, dropping any that are not explicitly mentioned:
.. code-block:: python
db["places"].transform(
add_foreign_keys=(("continent",))
)
Dropping foreign key constraints
--------------------------------

32
tests/test_transform.py
View file

@ -429,7 +429,18 @@ def test_transform_add_foreign_keys_from_scratch(fresh_db):
)
def test_transform_add_foreign_keys_from_partial(fresh_db):
@pytest.mark.parametrize(
"add_foreign_keys",
(
("country", "continent"),
# Fully specified
(
("country", "country", "id"),
("continent", "continent", "id"),
),
),
)
def test_transform_add_foreign_keys_from_partial(fresh_db, add_foreign_keys):
_add_country_city_continent(fresh_db)
fresh_db["places"].insert(
_CAVEAU,
@ -440,7 +451,7 @@ def test_transform_add_foreign_keys_from_partial(fresh_db):
ForeignKey(table="places", column="city", other_table="city", other_column="id")
]
# Now add three more using .transform()
fresh_db["places"].transform(add_foreign_keys=("country", "continent"))
fresh_db["places"].transform(add_foreign_keys=add_foreign_keys)
# Should now have all three:
assert fresh_db["places"].foreign_keys == [
ForeignKey(
@ -458,7 +469,18 @@ def test_transform_add_foreign_keys_from_partial(fresh_db):
]
def test_transform_replace_foreign_keys(fresh_db):
@pytest.mark.parametrize(
"foreign_keys",
(
("country", "continent"),
# Fully specified
(
("country", "country", "id"),
("continent", "continent", "id"),
),
),
)
def test_transform_replace_foreign_keys(fresh_db, foreign_keys):
_add_country_city_continent(fresh_db)
fresh_db["places"].insert(
_CAVEAU,
@ -466,9 +488,7 @@ def test_transform_replace_foreign_keys(fresh_db):
)
assert len(fresh_db["places"].foreign_keys) == 1
# Replace with two different ones
fresh_db["places"].transform(
foreign_keys=("country", "continent"),
)
fresh_db["places"].transform(foreign_keys=foreign_keys)
assert fresh_db["places"].schema == (
'CREATE TABLE "places" (\n'
" [id] INTEGER,\n"