feat: add Docling JSON ingestion (#783)

* feat: add Docling JSON ingestion

Signed-off-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>

* update conversion as per review comments, add tests, revert Docling JSON disambiguation, document intricacies

Signed-off-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>

* Update docling/backend/json/docling_json_backend.py

Co-authored-by: Cesar Berrospi Ramis <75900930+ceberam@users.noreply.github.com>
Signed-off-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>

---------

Signed-off-by: Panos Vagenas <35837085+vagenas@users.noreply.github.com>
Co-authored-by: Cesar Berrospi Ramis <75900930+ceberam@users.noreply.github.com>

docling/backend/abstract_backend.py

@@ -27,7 +27,6 @@ class AbstractDocumentBackend(ABC):
     def supports_pagination(cls) -> bool:
         pass
 
-    @abstractmethod
     def unload(self):
         if isinstance(self.path_or_stream, BytesIO):
             self.path_or_stream.close()

docling/backend/json/docling_json_backend.py

@@ -0,0 +1,58 @@
+from io import BytesIO
+from pathlib import Path
+from typing import Union
+
+from docling_core.types.doc import DoclingDocument
+from typing_extensions import override
+
+from docling.backend.abstract_backend import DeclarativeDocumentBackend
+from docling.datamodel.base_models import InputFormat
+from docling.datamodel.document import InputDocument
+
+
+class DoclingJSONBackend(DeclarativeDocumentBackend):
+    @override
+    def __init__(
+        self, in_doc: InputDocument, path_or_stream: Union[BytesIO, Path]
+    ) -> None:
+        super().__init__(in_doc, path_or_stream)
+
+        # given we need to store any actual conversion exception for raising it from
+        # convert(), this captures the successful result or the actual error in a
+        # mutually exclusive way:
+        self._doc_or_err = self._get_doc_or_err()
+
+    @override
+    def is_valid(self) -> bool:
+        return isinstance(self._doc_or_err, DoclingDocument)
+
+    @classmethod
+    @override
+    def supports_pagination(cls) -> bool:
+        return False
+
+    @classmethod
+    @override
+    def supported_formats(cls) -> set[InputFormat]:
+        return {InputFormat.JSON_DOCLING}
+
+    def _get_doc_or_err(self) -> Union[DoclingDocument, Exception]:
+        try:
+            json_data: Union[str, bytes]
+            if isinstance(self.path_or_stream, Path):
+                with open(self.path_or_stream, encoding="utf-8") as f:
+                    json_data = f.read()
+            elif isinstance(self.path_or_stream, BytesIO):
+                json_data = self.path_or_stream.getvalue()
+            else:
+                raise RuntimeError(f"Unexpected: {type(self.path_or_stream)=}")
+            return DoclingDocument.model_validate_json(json_data=json_data)
+        except Exception as e:
+            return e
+
+    @override
+    def convert(self) -> DoclingDocument:
+        if isinstance(self._doc_or_err, DoclingDocument):
+            return self._doc_or_err
+        else:
+            raise self._doc_or_err

docling/datamodel/base_models.py

@@ -41,6 +41,7 @@ class InputFormat(str, Enum):
     MD = "md"
     XLSX = "xlsx"
     XML_USPTO = "xml_uspto"
+    JSON_DOCLING = "json_docling"
 
 
 class OutputFormat(str, Enum):
@@ -62,6 +63,7 @@ FormatToExtensions: Dict[InputFormat, List[str]] = {
     InputFormat.ASCIIDOC: ["adoc", "asciidoc", "asc"],
     InputFormat.XLSX: ["xlsx"],
     InputFormat.XML_USPTO: ["xml", "txt"],
+    InputFormat.JSON_DOCLING: ["json"],
 }
 
 FormatToMimeType: Dict[InputFormat, List[str]] = {
@@ -90,6 +92,7 @@ FormatToMimeType: Dict[InputFormat, List[str]] = {
         "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
     ],
     InputFormat.XML_USPTO: ["application/xml", "text/plain"],
+    InputFormat.JSON_DOCLING: ["application/json"],
 }
 
 MimeTypeToFormat: dict[str, list[InputFormat]] = {

docling/datamodel/document.py

@@ -350,6 +350,8 @@ class _DocumentConversionInput(BaseModel):
             mime = FormatToMimeType[InputFormat.HTML][0]
         elif ext in FormatToExtensions[InputFormat.MD]:
             mime = FormatToMimeType[InputFormat.MD][0]
+        elif ext in FormatToExtensions[InputFormat.JSON_DOCLING]:
+            mime = FormatToMimeType[InputFormat.JSON_DOCLING][0]
         return mime
 
     @staticmethod

docling/document_converter.py

@@ -11,6 +11,7 @@ from docling.backend.abstract_backend import AbstractDocumentBackend
 from docling.backend.asciidoc_backend import AsciiDocBackend
 from docling.backend.docling_parse_v2_backend import DoclingParseV2DocumentBackend
 from docling.backend.html_backend import HTMLDocumentBackend
+from docling.backend.json.docling_json_backend import DoclingJSONBackend
 from docling.backend.md_backend import MarkdownDocumentBackend
 from docling.backend.msexcel_backend import MsExcelDocumentBackend
 from docling.backend.mspowerpoint_backend import MsPowerpointDocumentBackend
@@ -136,6 +137,9 @@ def _get_default_option(format: InputFormat) -> FormatOption:
         InputFormat.PDF: FormatOption(
             pipeline_cls=StandardPdfPipeline, backend=DoclingParseV2DocumentBackend
         ),
+        InputFormat.JSON_DOCLING: FormatOption(
+            pipeline_cls=SimplePipeline, backend=DoclingJSONBackend
+        ),
     }
     if (options := format_to_default_options.get(format)) is not None:
         return options

tests/test_backend_docling_json.py

@@ -0,0 +1,58 @@
+"""Test methods in module docling.backend.json.docling_json_backend.py."""
+
+from io import BytesIO
+from pathlib import Path
+
+import pytest
+from pydantic import ValidationError
+
+from docling.backend.json.docling_json_backend import DoclingJSONBackend
+from docling.datamodel.base_models import InputFormat
+from docling.datamodel.document import DoclingDocument, InputDocument
+
+GT_PATH: Path = Path("./tests/data/groundtruth/docling_v2/2206.01062.json")
+
+
+def test_convert_valid_docling_json():
+    """Test ingestion of valid Docling JSON."""
+    cls = DoclingJSONBackend
+    path_or_stream = GT_PATH
+    in_doc = InputDocument(
+        path_or_stream=path_or_stream,
+        format=InputFormat.JSON_DOCLING,
+        backend=cls,
+    )
+    backend = cls(
+        in_doc=in_doc,
+        path_or_stream=path_or_stream,
+    )
+    assert backend.is_valid()
+
+    act_doc = backend.convert()
+    act_data = act_doc.export_to_dict()
+
+    exp_doc = DoclingDocument.load_from_json(GT_PATH)
+    exp_data = exp_doc.export_to_dict()
+
+    assert act_data == exp_data
+
+
+def test_invalid_docling_json():
+    """Test ingestion of invalid Docling JSON."""
+    cls = DoclingJSONBackend
+    path_or_stream = BytesIO(b"{}")
+    in_doc = InputDocument(
+        path_or_stream=path_or_stream,
+        format=InputFormat.JSON_DOCLING,
+        backend=cls,
+        filename="foo",
+    )
+    backend = cls(
+        in_doc=in_doc,
+        path_or_stream=path_or_stream,
+    )
+
+    assert not backend.is_valid()
+
+    with pytest.raises(ValidationError):
+        backend.convert()

tests/test_input_doc.py

@@ -124,6 +124,25 @@ def test_guess_format(tmp_path):
     doc_path.write_text("xyz", encoding="utf-8")
     assert dci._guess_format(doc_path) == None
 
+    # Valid Docling JSON
+    test_str = '{"name": ""}'
+    stream = DocumentStream(name="test.json", stream=BytesIO(f"{test_str}".encode()))
+    assert dci._guess_format(stream) == InputFormat.JSON_DOCLING
+    doc_path = temp_dir / "test.json"
+    doc_path.write_text(test_str, encoding="utf-8")
+    assert dci._guess_format(doc_path) == InputFormat.JSON_DOCLING
+
+    # Non-Docling JSON
+    # TODO: Docling JSON is currently the single supported JSON flavor and the pipeline
+    # will try to validate *any* JSON (based on suffix/MIME) as Docling JSON; proper
+    # disambiguation seen as part of https://github.com/DS4SD/docling/issues/802
+    test_str = "{}"
+    stream = DocumentStream(name="test.json", stream=BytesIO(f"{test_str}".encode()))
+    assert dci._guess_format(stream) == InputFormat.JSON_DOCLING
+    doc_path = temp_dir / "test.json"
+    doc_path.write_text(test_str, encoding="utf-8")
+    assert dci._guess_format(doc_path) == InputFormat.JSON_DOCLING
+
 
 def _make_input_doc(path):
     in_doc = InputDocument(