Creates a data model for the document consumption, allowing stronger typing of arguments and setting of some information about the file only once

src/documents/data_models.py

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+import dataclasses
+import datetime
+import enum
+from pathlib import Path
+from typing import List
+from typing import Optional
+
+import magic
+
+
+@dataclasses.dataclass
+class DocumentMetadataOverrides:
+    """
+    Manages overrides for document fields which normally would
+    be set from content or matching.  All fields default to None,
+    meaning no override is happening
+    """
+
+    filename: Optional[str] = None
+    title: Optional[str] = None
+    correspondent_id: Optional[int] = None
+    document_type_id: Optional[int] = None
+    tag_ids: Optional[List[int]] = None
+    created: Optional[datetime.datetime] = None
+    asn: Optional[int] = None
+    owner_id: Optional[int] = None
+
+
+class DocumentSource(enum.IntEnum):
+    """
+    The source of an incoming document.  May have other uses in the future
+    """
+
+    ConsumeFolder = enum.auto()
+    ApiUpload = enum.auto()
+    MailFetch = enum.auto()
+
+
+@dataclasses.dataclass
+class ConsumableDocument:
+    """
+    Encapsulates an incoming document, either from consume folder, API upload
+    or mail fetching and certain useful operations on it.
+    """
+
+    source: DocumentSource
+    original_file: Path
+    mime_type: str = dataclasses.field(init=False, default=None)
+
+    def __post_init__(self):
+        """
+        After a dataclass is initialized, this is called to finalize some data
+        1. Make sure the original path is an absolute, fully qualified path
+        2. Get the mime type of the file
+        """
+        # Always fully qualify the path first thing
+        # Just in case, convert to a path if it's a str
+        self.original_file = Path(self.original_file).resolve()
+
+        # Get the file type once at init
+        # Note this function isn't called when the object is unpickled
+        self.mime_type = magic.from_file(self.original_file, mime=True)