langchain_v0.py — langchain Source File

Source Code

"""Derivations of standard content blocks from LangChain v0 multimodal content."""

from typing import Any, cast

from langchain_core.messages import content as types


def _convert_v0_multimodal_input_to_v1(
    content: list[types.ContentBlock],
) -> list[types.ContentBlock]:
    """Convert v0 multimodal blocks to v1 format.

    During the `content_blocks` parsing process, we wrap blocks not recognized as a v1
    block as a `'non_standard'` block with the original block stored in the `value`
    field. This function attempts to unpack those blocks and convert any v0 format
    blocks to v1 format.

    If conversion fails, the block is left as a `'non_standard'` block.

    Args:
        content: List of content blocks to process.

    Returns:
        v1 content blocks.
    """
    converted_blocks = []
    unpacked_blocks: list[dict[str, Any]] = [
        cast("dict[str, Any]", block)
        if block.get("type") != "non_standard"
        else block["value"]  # type: ignore[typeddict-item]  # this is only non-standard blocks
        for block in content
    ]
    for block in unpacked_blocks:
        if block.get("type") in {"image", "audio", "file"} and "source_type" in block:
            converted_block = _convert_legacy_v0_content_block_to_v1(block)
            converted_blocks.append(cast("types.ContentBlock", converted_block))
        elif block.get("type") in types.KNOWN_BLOCK_TYPES:
            # Guard in case this function is used outside of the .content_blocks flow
            converted_blocks.append(cast("types.ContentBlock", block))
        else:
            converted_blocks.append({"type": "non_standard", "value": block})

    return converted_blocks


def _convert_legacy_v0_content_block_to_v1(
    block: dict,
) -> types.ContentBlock | dict:
    """Convert a LangChain v0 content block to v1 format.

    Preserves unknown keys as extras to avoid data loss.

    Returns the original block unchanged if it's not in v0 format.
    """

    def _extract_v0_extras(block_dict: dict, known_keys: set[str]) -> dict[str, Any]:
        """Extract unknown keys from v0 block to preserve as extras.

        Args:
            block_dict: The original v0 block dictionary.
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