feat: ByteStream auto mime_type detection and base64 (de)encoding

haystack_experimental/dataclasses/__init__.py

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+from haystack_experimental.dataclasses.byte_stream import ByteStream
 from haystack_experimental.dataclasses.chat_message import (
     ChatMessage,
     ChatMessageContentT,
@@ -18,12 +19,14 @@
 
 __all__ = [
     "AsyncStreamingCallbackT",
+    "ByteStream",
     "ChatMessage",
+    "ChatMessageContentT",
     "ChatRole",
+    "MediaContent",
     "StreamingCallbackT",
+    "TextContent",
     "ToolCall",
     "ToolCallResult",
-    "TextContent",
-    "ChatMessageContentT",
     "Tool",
 ]

haystack_experimental/dataclasses/byte_stream.py

@@ -0,0 +1,152 @@
+# SPDX-FileCopyrightText: 2022-present deepset GmbH <[email protected]>
+#
+# SPDX-License-Identifier: Apache-2.0
+"""
+Data classes for representing binary data in the Haystack API. The ByteStream class can be used to represent binary data
+in the API, and can be converted to and from base64 encoded strings, dictionaries, and files. This is particularly
+useful for representing media files in chat messages.
+"""
+
+import logging
+import mimetypes
+from base64 import b64encode, b64decode
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class ByteStream:
+    """
+    Base data class representing a binary object in the Haystack API.
+    """
+
+    data: bytes
+    meta: Dict[str, Any] = field(default_factory=dict, hash=False)
+    mime_type: Optional[str] = field(default=None)
+
+    @property
+    def type(self) -> Optional[str]:
+        """
+        Return the type of the ByteStream. This is the first part of the mime type, or None if the mime type is not set.
+
+        :return: The type of the ByteStream.
+        """
+        if self.mime_type:
+            return self.mime_type.split("/", maxsplit=1)[0]
+        return None
+
+    @property
+    def subtype(self) -> Optional[str]:
+        """
+        Return the subtype of the ByteStream. This is the second part of the mime type,
+        or None if the mime type is not set.
+
+        :return: The subtype of the ByteStream.
+        """
+        if self.mime_type:
+            return self.mime_type.split("/", maxsplit=1)[-1]
+        return None
+
+    def to_file(self, destination_path: Path):
+        """
+        Write the ByteStream to a file. Note: the metadata will be lost.
+
+        :param destination_path: The path to write the ByteStream to.
+        """
+        with open(destination_path, "wb") as fd:
+            fd.write(self.data)
+
+    @classmethod
+    def from_file_path(
+        cls, filepath: Path, mime_type: Optional[str] = None, meta: Optional[Dict[str, Any]] = None
+    ) -> "ByteStream":
+        """
+        Create a ByteStream from the contents read from a file.
+
+        :param filepath: A valid path to a file.
+        :param mime_type: The mime type of the file.
+        :param meta: Additional metadata to be stored with the ByteStream.
+        """
+        if mime_type is None:
+            mime_type = mimetypes.guess_type(filepath)[0]
+            if mime_type is None:
+                logger.warning("Could not determine mime type for file %s", filepath)
+
+        with open(filepath, "rb") as fd:
+            return cls(data=fd.read(), mime_type=mime_type, meta=meta or {})
+
+    @classmethod
+    def from_string(
+        cls, text: str, encoding: str = "utf-8", mime_type: Optional[str] = None, meta: Optional[Dict[str, Any]] = None
+    ) -> "ByteStream":
+        """
+        Create a ByteStream encoding a string.
+
+        :param text: The string to encode
+        :param encoding: The encoding used to convert the string into bytes
+        :param mime_type: The mime type of the file.
+        :param meta: Additional metadata to be stored with the ByteStream.
+        """
+        return cls(data=text.encode(encoding), mime_type=mime_type, meta=meta or {})
+
+    def to_string(self, encoding: str = "utf-8") -> str:
+        """
+        Convert the ByteStream to a string, metadata will not be included.
+
+        :param encoding: The encoding used to convert the bytes to a string. Defaults to "utf-8".
+        :returns: The string representation of the ByteStream.
+        :raises: UnicodeDecodeError: If the ByteStream data cannot be decoded with the specified encoding.
+        """
+        return self.data.decode(encoding)
+
+    @classmethod
+    def from_base64(
+        cls,
+        base64_string: str,
+        encoding: str = "utf-8",
+        meta: Optional[Dict[str, Any]] = None,
+        mime_type: Optional[str] = None,
+    ) -> "ByteStream":
+        """
+        Create a ByteStream from a base64 encoded string.
+
+        :param base64_string: The base64 encoded string representation of the ByteStream data.
+        :param encoding: The encoding used to convert the base64 string into bytes.
+        :param meta: Additional metadata to be stored with the ByteStream.
+        :param mime_type: The mime type of the file.
+        :returns: A new ByteStream instance.
+        """
+        return cls(data=b64decode(base64_string.encode(encoding)), meta=meta or {}, mime_type=mime_type)
+
+    def to_base64(self, encoding: str = "utf-8") -> str:
+        """
+        Convert the ByteStream data to a base64 encoded string.
+
+        :returns: The base64 encoded string representation of the ByteStream data.
+        """
+        return b64encode(self.data).decode(encoding)
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any], encoding: str = "utf-8") -> "ByteStream":
+        """
+        Create a ByteStream from a dictionary.
+
+        :param data: The dictionary representation of the ByteStream.
+        :param encoding: The encoding used to convert the base64 string into bytes.
+        :returns: A new ByteStream instance.
+        """
+        return cls.from_base64(data["data"], encoding=encoding, meta=data.get("meta"), mime_type=data.get("mime_type"))
+
+    def to_dict(self, encoding: str = "utf-8"):
+        """
+        Convert the ByteStream to a dictionary.
+
+        :param encoding: The encoding used to convert the bytes to a string. Defaults to "utf-8".
+        :returns: The dictionary representation of the ByteStream.
+        :raises: UnicodeDecodeError: If the ByteStream data cannot be decoded with the specified encoding.
+        """
+        return {"data": self.to_base64(encoding=encoding), "meta": self.meta, "mime_type": self.mime_type}

test/dataclasses/test_byte_stream.py

@@ -0,0 +1,91 @@
+import pytest
+from base64 import b64encode
+from pathlib import Path
+from unittest.mock import mock_open, patch
+
+from haystack_experimental.dataclasses.byte_stream import ByteStream
+
+@pytest.fixture
+def byte_stream():
+    test_data = b"test data"
+    test_meta = {"key": "value"}
+    test_mime = "text/plain"
+    return ByteStream(data=test_data, meta=test_meta, mime_type=test_mime)
+
+def test_init(byte_stream):
+    assert byte_stream.data == b"test data"
+    assert byte_stream.meta == {"key": "value"}
+    assert byte_stream.mime_type == "text/plain"
+
+def test_type_property(byte_stream):
+    assert byte_stream.type == "text"
+    stream_without_mime = ByteStream(data=b"test data")
+    assert stream_without_mime.type is None
+
+def test_subtype_property(byte_stream):
+    assert byte_stream.subtype == "plain"
+    stream_without_mime = ByteStream(data=b"test data")
+    assert stream_without_mime.subtype is None
+
+@patch("builtins.open", new_callable=mock_open)
+def test_to_file(mock_file, byte_stream):
+    path = Path("test.txt")
+    byte_stream.to_file(path)
+    mock_file.assert_called_once_with(path, "wb")
+    mock_file().write.assert_called_once_with(b"test data")
+
+@patch("builtins.open", new_callable=mock_open, read_data=b"test data")
+def test_from_file_path(mock_file):
+    path = Path("test.txt")
+    with patch("mimetypes.guess_type", return_value=("text/plain", None)):
+        byte_stream = ByteStream.from_file_path(path)
+        assert byte_stream.data == b"test data"
+        assert byte_stream.mime_type == "text/plain"
+
+@patch("mimetypes.guess_type", return_value=(None, None))
+@patch("haystack_experimental.dataclasses.byte_stream.logger.warning")
+def test_from_file_path_unknown_mime(mock_warning, _, byte_stream):
+    path = Path("test.txt")
+    with patch("builtins.open", new_callable=mock_open, read_data=b"test data"):
+        byte_stream = ByteStream.from_file_path(path)
+        assert byte_stream.mime_type is None
+        mock_warning.assert_called_once()
+
+def test_from_string():
+    text = "Hello, World!"
+    byte_stream = ByteStream.from_string(text, mime_type="text/plain")
+    assert byte_stream.data == text.encode("utf-8")
+    assert byte_stream.mime_type == "text/plain"
+
+def test_to_string():
+    byte_stream = ByteStream(data=b"Hello, World!")
+    assert byte_stream.to_string() == "Hello, World!"
+
+def test_from_base64():
+    base64_string = b64encode(b"test data").decode("utf-8")
+    byte_stream = ByteStream.from_base64(base64_string, mime_type="text/plain")
+    assert byte_stream.data == b"test data"
+    assert byte_stream.mime_type == "text/plain"
+
+def test_to_base64(byte_stream):
+    expected = b64encode(b"test data").decode("utf-8")
+    assert byte_stream.to_base64() == expected
+
+def test_from_dict():
+    data = {
+        "data": b64encode(b"test data").decode("utf-8"),
+        "meta": {"key": "value"},
+        "mime_type": "text/plain",
+    }
+    byte_stream = ByteStream.from_dict(data)
+    assert byte_stream.data == b"test data"
+    assert byte_stream.meta == {"key": "value"}
+    assert byte_stream.mime_type == "text/plain"
+
+def test_to_dict(byte_stream):
+    expected = {
+        "data": b64encode(b"test data").decode("utf-8"),
+        "meta": {"key": "value"},
+        "mime_type": "text/plain",
+    }
+    assert byte_stream.to_dict() == expected