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refactor(targets): Added a class method to instantiate JSONSchemaToSQL from the target configuration #2782

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10 changes: 8 additions & 2 deletions docs/guides/sql-target.md
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,10 @@ def custom_array_to_sql(jsonschema: dict) -> VectorType | sa.types.VARCHAR:
class MyConnector(SQLConnector):
@functools.cached_property
def jsonschema_to_sql(self):
to_sql = JSONSchemaToSQL()
to_sql = JSONSchemaToSQL.from_config(
self.config,
max_varchar_length=self.max_varchar_length,
)
to_sql.register_type_handler("array", custom_array_to_sql)
return to_sql
```
Expand All @@ -46,7 +49,10 @@ from my_sqlalchemy_dialect import URI
class MyConnector(SQLConnector):
@functools.cached_property
def jsonschema_to_sql(self):
to_sql = JSONSchemaToSQL()
to_sql = JSONSchemaToSQL.from_config(
self.config,
max_varchar_length=self.max_varchar_length,
)
to_sql.register_format_handler("uri", URI)
return to_sql
```
39 changes: 38 additions & 1 deletion singer_sdk/connectors/sql.py
Original file line number Diff line number Diff line change
Expand Up @@ -276,6 +276,35 @@ def __init__(self, *, max_varchar_length: int | None = None) -> None:

self._fallback_type: type[sa.types.TypeEngine] = sa.types.VARCHAR

@classmethod
def from_config(
cls: type[JSONSchemaToSQL],
config: dict, # noqa: ARG003
*,
max_varchar_length: int | None,
) -> JSONSchemaToSQL:
"""Create a new instance from a configuration dictionary.

Override this to instantiate this converter with values from the target's
configuration dictionary.

.. code-block:: python

class CustomJSONSchemaToSQL(JSONSchemaToSQL):
@classmethod
def from_config(cls, config, **kwargs):
return cls(max_varchar_length=config.get("max_varchar_length"))

Args:
config: The configuration dictionary.
max_varchar_length: The absolute maximum length for VARCHAR columns that
the database supports.

Returns:
A new instance of the class.
"""
return cls(max_varchar_length=max_varchar_length)

def _invoke_handler( # noqa: PLR6301
self,
handler: JSONtoSQLHandler,
Expand Down Expand Up @@ -487,6 +516,11 @@ class SQLConnector: # noqa: PLR0904
#: a custom mapping for your SQL dialect.
sql_to_jsonschema_converter: type[SQLToJSONSchema] = SQLToJSONSchema

#: The JSON-to-SQL type mapper class for this SQL connector. Override this property
#: with a subclass of :class:`~singer_sdk.connectors.sql.JSONSchemaToSQL` to provide
#: a custom mapping for your SQL dialect.
jsonschema_to_sql_converter: type[JSONSchemaToSQL] = JSONSchemaToSQL

def __init__(
self,
config: dict | None = None,
Expand Down Expand Up @@ -537,7 +571,10 @@ def jsonschema_to_sql(self) -> JSONSchemaToSQL:

.. versionadded:: 0.42.0
"""
return JSONSchemaToSQL(max_varchar_length=self.max_varchar_length)
return self.jsonschema_to_sql_converter.from_config(
self.config,
max_varchar_length=self.max_varchar_length,
)

@contextmanager
def _connect(self) -> t.Iterator[sa.engine.Connection]:
Expand Down
4 changes: 2 additions & 2 deletions tests/core/test_connector_sql.py
Original file line number Diff line number Diff line change
Expand Up @@ -654,7 +654,7 @@ def test_unknown_format(self, json_schema_to_sql: JSONSchemaToSQL):
assert isinstance(result, sa.types.VARCHAR)

def test_custom_fallback(self):
json_schema_to_sql = JSONSchemaToSQL()
json_schema_to_sql = JSONSchemaToSQL(max_varchar_length=None)
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json_schema_to_sql.fallback_type = sa.types.CHAR
jsonschema_type = {"cannot": "compute"}
result = json_schema_to_sql.to_sql_type(jsonschema_type)
Expand All @@ -668,7 +668,7 @@ def handle_raw_string(self, schema):

return super().handle_raw_string(schema)

json_schema_to_sql = CustomJSONSchemaToSQL()
json_schema_to_sql = CustomJSONSchemaToSQL(max_varchar_length=None)
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vanilla = {"type": ["string"]}
result = json_schema_to_sql.to_sql_type(vanilla)
Expand Down