AirbyteLib: Add len() support on SQL datasets and Mapping behaviors f…

…or ReadResult (airbytehq#34763)

airbyte-lib/airbyte_lib/datasets/_lazy.py

@@ -20,6 +20,7 @@ def __init__(
         iterator: Iterator[Mapping[str, Any]],
     ) -> None:
         self._iterator: Iterator[Mapping[str, Any]] = iterator
+        super().__init__()
 
     @overrides
     def __iter__(self) -> Iterator[Mapping[str, Any]]:

airbyte-lib/airbyte_lib/datasets/_sql.py

@@ -5,7 +5,7 @@
 from typing import TYPE_CHECKING, Any, cast
 
 from overrides import overrides
-from sqlalchemy import and_, text
+from sqlalchemy import and_, func, select, text
 
 from airbyte_lib.datasets._base import DatasetBase
 
@@ -33,9 +33,11 @@ def __init__(
         stream_name: str,
         query_statement: Selectable,
     ) -> None:
+        self._length: int | None = None
         self._cache: SQLCacheBase = cache
         self._stream_name: str = stream_name
         self._query_statement: Selectable = query_statement
+        super().__init__()
 
     @property
     def stream_name(self) -> str:
@@ -48,6 +50,18 @@ def __iter__(self) -> Iterator[Mapping[str, Any]]:
                 # https://pydoc.dev/sqlalchemy/latest/sqlalchemy.engine.row.RowMapping.html
                 yield cast(Mapping[str, Any], row._mapping)  # noqa: SLF001
 
+    def __len__(self) -> int:
+        """Return the number of records in the dataset.
+
+        This method caches the length of the dataset after the first call.
+        """
+        if self._length is None:
+            count_query = select([func.count()]).select_from(self._query_statement.alias())
+            with self._cache.get_sql_connection() as conn:
+                self._length = conn.execute(count_query).scalar()
+
+        return self._length
+
     def to_pandas(self) -> DataFrame:
         return self._cache.get_pandas_dataframe(self._stream_name)
 
@@ -85,16 +99,19 @@ class CachedDataset(SQLDataset):
     """
 
     def __init__(self, cache: SQLCacheBase, stream_name: str) -> None:
-        self._cache: SQLCacheBase = cache
-        self._stream_name: str = stream_name
-        self._query_statement: Selectable = self.to_sql_table().select()
+        self._sql_table: Table = cache.get_sql_table(stream_name)
+        super().__init__(
+            cache=cache,
+            stream_name=stream_name,
+            query_statement=self._sql_table.select(),
+        )
 
     @overrides
     def to_pandas(self) -> DataFrame:
         return self._cache.get_pandas_dataframe(self._stream_name)
 
     def to_sql_table(self) -> Table:
-        return self._cache.get_sql_table(self._stream_name)
+        return self._sql_table
 
     def __eq__(self, value: object) -> bool:
         """Return True if the value is a CachedDataset with the same cache and stream name.

airbyte-lib/airbyte_lib/results.py

@@ -1,20 +1,21 @@
 # Copyright (c) 2023 Airbyte, Inc., all rights reserved.
 from __future__ import annotations
 
+from collections.abc import Mapping
 from typing import TYPE_CHECKING
 
 from airbyte_lib.datasets import CachedDataset
 
 
 if TYPE_CHECKING:
-    from collections.abc import Iterator, Mapping
+    from collections.abc import Iterator
 
     from sqlalchemy.engine import Engine
 
     from airbyte_lib.caches import SQLCacheBase
 
 
-class ReadResult:
+class ReadResult(Mapping[str, CachedDataset]):
     def __init__(
         self, processed_records: int, cache: SQLCacheBase, processed_streams: list[str]
     ) -> None:
@@ -28,12 +29,18 @@ def __getitem__(self, stream: str) -> CachedDataset:
 
         return CachedDataset(self._cache, stream)
 
-    def __contains__(self, stream: str) -> bool:
+    def __contains__(self, stream: object) -> bool:
+        if not isinstance(stream, str):
+            return False
+
         return stream in self._processed_streams
 
     def __iter__(self) -> Iterator[str]:
         return self._processed_streams.__iter__()
 
+    def __len__(self) -> int:
+        return len(self._processed_streams)
+
     def get_sql_engine(self) -> Engine:
         return self._cache.get_sql_engine()
 

airbyte-lib/tests/integration_tests/test_integration.py

@@ -217,6 +217,35 @@ def test_sync_to_duckdb(expected_test_stream_data: dict[str, list[dict[str, str
     assert_cache_data(expected_test_stream_data, cache)
 
 
+def test_read_result_mapping():
+    source = ab.get_connector("source-test", config={"apiKey": "test"})
+    result: ReadResult = source.read()
+    assert len(result) == 2
+    assert isinstance(result, Mapping)
+    assert "stream1" in result
+    assert "stream2" in result
+    assert "stream3" not in result
+    assert result.keys() == {"stream1", "stream2"}
+
+
+def test_dataset_list_and_len(expected_test_stream_data):
+    source = ab.get_connector("source-test", config={"apiKey": "test"})
+    result: ReadResult = source.read()
+    stream_1 = result["stream1"]
+    assert len(stream_1) == 2
+    assert len(list(stream_1)) == 2
+    # Make sure we can iterate over the stream after calling len
+    assert list(stream_1) == [{"column1": "value1", "column2": 1}, {"column1": "value2", "column2": 2}]
+    # Make sure we can iterate over the stream a second time
+    assert list(stream_1) == [{"column1": "value1", "column2": 1}, {"column1": "value2", "column2": 2}]
+
+    assert isinstance(result, Mapping)
+    assert "stream1" in result
+    assert "stream2" in result
+    assert "stream3" not in result
+    assert result.keys() == {"stream1", "stream2"}
+
+
 def test_read_from_cache(expected_test_stream_data: dict[str, list[dict[str, str | int]]]):
     """
     Test that we can read from a cache that already has data (identigier by name)