Provide versions of a document as a list of Documents

src/caselawclient/errors.py

@@ -83,3 +83,14 @@ class DocumentNotFoundError(MarklogicAPIError):
     # This error does not come from Marklogic, but is an error raised by this API...
     status_code = 404
     default_message = "The document was not found"
+
+
+class NotSupportedOnVersion(MarklogicAPIError):
+    # This error does not come from Marklogic, but is an error raised by this API...
+    status_code = 400
+    default_message = "An operation was attempted on a version of a document which cannot occur on a version."
+
+
+class OnlySupportedOnVersion(MarklogicAPIError):
+    status_code = 400
+    default_message = "The operation requested cannot be performed on a document that is not a version."

src/caselawclient/models/documents.py

@@ -7,7 +7,13 @@
 from lxml import etree
 from requests_toolbelt.multipart import decoder
 
-from ..errors import DocumentNotFoundError
+from caselawclient.models.utilities import extract_version
+
+from ..errors import (
+    DocumentNotFoundError,
+    NotSupportedOnVersion,
+    OnlySupportedOnVersion,
+)
 from ..xml_helpers import get_xpath_match_string, get_xpath_match_strings
 from .utilities import VersionsDict, get_judgment_root, render_versions
 from .utilities.aws import (
@@ -237,6 +243,44 @@ def versions(self) -> list[VersionsDict]:
         except AttributeError:
             return []
 
+    @cached_property
+    def versions_as_documents(self) -> list[Any]:
+        """
+        Returns a list of `Document` subclasses corresponding to the versions of the document. The first entry is:
+           * the most recent
+           * the highest numbered
+
+        Note that this is only valid on the managed document -- a `DLS-DOCUMENTVERSION` error will occur if the document
+        this is called on is itself a version.
+        """
+        if self.is_version:
+            raise NotSupportedOnVersion(
+                "Cannot get versions of a version for {self.uri}"
+            )
+        docs = []
+        for version in self.versions:
+            doc_uri = DocumentURIString(version["uri"])
+            docs.append(self.api_client.get_document_by_uri(doc_uri))
+        return docs
+
+    @cached_property
+    def version_number(self) -> int:
+        """
+        Note that the highest number is the most recent version.
+        Raises an exception if it is not a version (e.g. /2022/eat/1 is not a version)
+        """
+        version = extract_version(self.uri)
+        if version == 0:
+            raise OnlySupportedOnVersion(
+                f"Version number requested for {self.uri} which is not a version"
+            )
+        return version
+
+    @cached_property
+    def is_version(self) -> bool:
+        "Is this document a potentially historic version of a document, or is it the main document itself?"
+        return extract_version(self.uri) != 0
+
     @cached_property
     def content_as_xml(self) -> str:
         return self.api_client.get_judgment_xml(self.uri, show_unpublished=True)

tests/models/test_documents.py

@@ -5,7 +5,11 @@
 from lxml import etree
 
 from caselawclient.Client import MarklogicApiClient
-from caselawclient.errors import DocumentNotFoundError
+from caselawclient.errors import (
+    DocumentNotFoundError,
+    NotSupportedOnVersion,
+    OnlySupportedOnVersion,
+)
 from caselawclient.models.documents import (
     DOCUMENT_STATUS_HOLD,
     DOCUMENT_STATUS_IN_PROGRESS,
@@ -169,6 +173,32 @@ def test_document_best_identifier(self, mock_api_client):
         example_document = Document("uri", mock_api_client)
         assert example_document.best_human_identifier is None
 
+    def test_document_version_of_a_version_fails(self, mock_api_client):
+        version_document = Document("test/1234_xml_versions/9-1234", mock_api_client)
+        with pytest.raises(NotSupportedOnVersion):
+            version_document.versions_as_documents
+
+    def test_document_versions_happy_case(self, mock_api_client):
+        version_document = Document("test/1234", mock_api_client)
+        version_document.versions = [
+            {"uri": "test/1234_xml_versions/2-1234.xml"},
+            {"uri": "test/1234_xml_versions/1-1234.xml"},
+        ]
+        version_document.versions_as_documents[
+            0
+        ].uri = "test/1234_xml_versions/2-1234.xml"
+
+    def test_document_version_number_when_not_version(self, mock_api_client):
+        base_document = Document("test/1234", mock_api_client)
+        with pytest.raises(OnlySupportedOnVersion):
+            base_document.version_number
+        assert not base_document.is_version
+
+    def test_document_version_number_when_is_version(self, mock_api_client):
+        version_document = Document("test/1234_xml_versions/9-1234", mock_api_client)
+        assert version_document.version_number == 9
+        assert version_document.is_version
+
 
 class TestDocumentValidation:
     def test_judgment_is_failure(self, mock_api_client):