reading and displaying PDF metadata

Pipfile

@@ -27,6 +27,7 @@ langdetect = "*"
 pdftotext = "*"
 pathvalidate = "*"
 pillow = "*"
+pikepdf = "*"
 python-gnupg = "*"
 python-dotenv = "*"
 python-dateutil = "*"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "3c187671ead11714d48b56f4714b145f68814e09edea818610b87f18b4f7f6fd"
+            "sha256": "3d576f289958226a7583e4c471c7f8c11bff6933bf093185f623cfb381a92412"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -433,7 +433,7 @@
                 "sha256:fe0ca120e3347c851c34a91041d574f3c588d832023906d8ae18d66d042e8a52",
                 "sha256:fe8e0152672f24d8bfdecc725f97e9013f2de1b41849150959526ca3562bd3ef"
             ],
-            "markers": "python_version < '3.9'",
+            "index": "pypi",
             "version": "==2.2.0"
         },
         "pillow": {

src-ui/src/app/components/document-detail/document-detail.component.html

@@ -15,7 +15,7 @@
             <span class="d-none d-lg-inline"> Download</span>
         </a>
 
-        <div class="btn-group" ngbDropdown role="group" *ngIf="metadata?.paperless__has_archive_version">
+        <div class="btn-group" ngbDropdown role="group" *ngIf="metadata?.has_archive_version">
             <button class="btn btn-sm btn-outline-primary dropdown-toggle-split" ngbDropdownToggle></button>
             <div class="dropdown-menu" ngbDropdownMenu>
                 <a ngbDropdownItem [href]="downloadOriginalUrl">Download original</a>
@@ -72,6 +72,7 @@
                 <li [ngbNavItem]="3">
                     <a ngbNavLink>Metadata</a>
                     <ng-template ngbNavContent>
+
                         <table class="table table-borderless">
                             <tbody>
                                 <tr>
@@ -83,23 +84,76 @@
                                     <td>{{document.added | date}}</td>
                                 </tr>
                                 <tr>
-                                    <td>MD5 Checksum</td>
+                                    <td>Original MD5 Checksum</td>
-                                    <td>{{metadata?.paperless__checksum}}</td>
+                                    <td>{{metadata?.original_checksum}}</td>
+                                </tr>
+                                <tr>
+                                    <td>Archive MD5 Checksum</td>
+                                    <td>{{metadata?.archived_checksum}}</td>
                                 </tr>
                                 <tr>
                                     <td>Original mime type</td>
-                                    <td>{{metadata?.paperless__mime_type}}</td>
+                                    <td>{{metadata?.original_mime_type}}</td>
                                 </tr>
                                 <tr>
                                     <td>Is archived?</td>
-                                    <td>{{metadata?.paperless__has_archive_version | yesno}}</td>
+                                    <td>{{metadata?.has_archive_version | yesno}}</td>
                                 </tr>
                                 <tr>
                                     <td>Media filename</td>
-                                    <td>{{metadata?.paperless__filename}}</td>
+                                    <td>{{metadata?.media_filename}}</td>
                                 </tr>
                             </tbody>
                         </table>
+
+                        <h6 *ngIf="metadata?.original_metadata.length > 0">
+                            <button type="button" class="btn btn-outline-secondary btn-sm mr-2"
+                                (click)="expandOriginalMetadata = !expandOriginalMetadata" aria-controls="collapseExample">
+                                <svg class="buttonicon" fill="currentColor" *ngIf="!expandOriginalMetadata">
+                                    <use xlink:href="assets/bootstrap-icons.svg#caret-down" />
+                                </svg>
+                                <svg class="buttonicon" fill="currentColor" *ngIf="expandOriginalMetadata">
+                                    <use xlink:href="assets/bootstrap-icons.svg#caret-up" />
+                                </svg>
+                            </button>
+                            Original document metadata
+                        </h6>
+
+                        <div #collapse="ngbCollapse" [(ngbCollapse)]="!expandOriginalMetadata">
+                            <table class="table table-borderless">
+                                <tbody>
+                                    <tr *ngFor="let m of metadata?.original_metadata">
+                                        <td>{{m.prefix}}:{{m.key}}</td>
+                                        <td>{{m.value}}</td>
+                                    </tr>
+                                </tbody>
+                            </table>
+                        </div>
+
+                        <h6 *ngIf="metadata?.has_archive_version && metadata?.archive_metadata.length > 0">
+                            <button type="button" class="btn btn-outline-secondary btn-sm mr-2"
+                                (click)="expandArchivedMetadata = !expandArchivedMetadata" aria-controls="collapseExample">
+                                <svg class="buttonicon" fill="currentColor" *ngIf="!expandArchivedMetadata">
+                                    <use xlink:href="assets/bootstrap-icons.svg#caret-down" />
+                                </svg>
+                                <svg class="buttonicon" fill="currentColor" *ngIf="expandArchivedMetadata">
+                                    <use xlink:href="assets/bootstrap-icons.svg#caret-up" />
+                                </svg>
+                            </button>
+                            Archived document metadata
+                        </h6>
+
+                        <div #collapse="ngbCollapse" [(ngbCollapse)]="!expandArchivedMetadata">
+                            <table class="table table-borderless">
+                                <tbody>
+                                    <tr *ngFor="let m of metadata?.archive_metadata">
+                                        <td>{{m.prefix}}:{{m.key}}</td>
+                                        <td>{{m.value}}</td>
+                                    </tr>
+                                </tbody>
+                            </table>
+                        </div>
+
                     </ng-template>
                 </li>
             </ul>
@@ -107,7 +161,8 @@
             <div [ngbNavOutlet]="nav" class="mt-2"></div>
 
             <button type="button" class="btn btn-outline-secondary" (click)="discard()">Discard</button>&nbsp;
-            <button type="button" class="btn btn-outline-primary" (click)="saveEditNext()" *ngIf="hasNext()">Save & edit next</button>&nbsp;
+            <button type="button" class="btn btn-outline-primary" (click)="saveEditNext()" *ngIf="hasNext()">Save & edit
+                next</button>&nbsp;
             <button type="submit" class="btn btn-primary">Save</button>&nbsp;
         </form>
     </div>

src-ui/src/app/components/document-detail/document-detail.component.ts

@@ -24,6 +24,9 @@ import { DocumentTypeEditDialogComponent } from '../manage/document-type-list/do
 })
 export class DocumentDetailComponent implements OnInit {
 
+  public expandOriginalMetadata = false;
+  public expandArchivedMetadata = false;
+
   documentId: number
   document: PaperlessDocument
   metadata: PaperlessDocumentMetadata

src-ui/src/app/data/paperless-document-metadata.ts

@@ -1,11 +1,13 @@
 export interface PaperlessDocumentMetadata {
     
-  paperless__checksum?: string
+  original_checksum?: string
 
-  paperless__mime_type?: string
+  archived_checksum?: string
 
-  paperless__filename?: string
+  original_mime_type?: string
 
-  paperless__has_archive_version?: boolean
+  media_filename?: string
+
+  has_archive_version?: boolean
 
 }

src/documents/tests/test_api.py

@@ -1,4 +1,5 @@
 import os
+import shutil
 import tempfile
 from unittest import mock
 
@@ -493,3 +494,34 @@ class TestDocumentApi(DirectoriesMixin, APITestCase):
         self.assertEqual(response.status_code, 400)
 
         async_task.assert_not_called()
+
+    def test_get_metadata(self):
+        doc = Document.objects.create(title="test", filename="file.pdf", mime_type="image/png")
+
+        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "thumbnails", "0000001.png"), doc.source_path)
+        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "simple.pdf"), doc.archive_path)
+
+        response = self.client.get(f"/api/documents/{doc.pk}/metadata/")
+        self.assertEqual(response.status_code, 200)
+
+        meta = response.data
+
+        self.assertEqual(meta['original_mime_type'], "image/png")
+        self.assertTrue(meta['has_archive_version'])
+        self.assertEqual(len(meta['original_metadata']), 0)
+        self.assertGreater(len(meta['archive_metadata']), 0)
+
+    def test_get_metadata_no_archive(self):
+        doc = Document.objects.create(title="test", filename="file.pdf", mime_type="application/pdf")
+
+        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "simple.pdf"), doc.source_path)
+
+        response = self.client.get(f"/api/documents/{doc.pk}/metadata/")
+        self.assertEqual(response.status_code, 200)
+
+        meta = response.data
+
+        self.assertEqual(meta['original_mime_type'], "application/pdf")
+        self.assertFalse(meta['has_archive_version'])
+        self.assertGreater(len(meta['original_metadata']), 0)
+        self.assertIsNone(meta['archive_metadata'])

src/documents/views.py

@@ -1,8 +1,11 @@
+import logging
 import os
+import re
 import tempfile
 from datetime import datetime
 from time import mktime
 
+import pikepdf
 from django.conf import settings
 from django.db.models import Count, Max
 from django.http import HttpResponse, HttpResponseBadRequest, Http404
@@ -160,16 +163,49 @@ class DocumentViewSet(RetrieveModelMixin,
             disposition, filename)
         return response
 
+    def get_metadata(self, file, type):
+        if not os.path.isfile(file):
+            return None
+
+        namespace_pattern = re.compile(r"\{(.*)\}(.*)")
+
+        result = []
+        if type == 'application/pdf':
+            pdf = pikepdf.open(file)
+            meta = pdf.open_metadata()
+            for key, value in meta.items():
+                if isinstance(value, list):
+                    value = " ".join([str(e) for e in value])
+                value = str(value)
+                try:
+                    m = namespace_pattern.match(key)
+                    result.append({
+                        "namespace": m.group(1),
+                        "prefix": meta.REVERSE_NS[m.group(1)],
+                        "key": m.group(2),
+                        "value": value
+                    })
+                except Exception as e:
+                    logging.getLogger(__name__).warning(
+                        f"Error while reading metadata {key}: {value}. Error: "
+                        f"{e}"
+                    )
+        return result
+
     @action(methods=['get'], detail=True)
     def metadata(self, request, pk=None):
         try:
             doc = Document.objects.get(pk=pk)
             return Response({
-                "paperless__checksum": doc.checksum,
+                "original_checksum": doc.checksum,
-                "paperless__mime_type": doc.mime_type,
+                "archived_checksum": doc.archive_checksum,
-                "paperless__filename": doc.filename,
+                "original_mime_type": doc.mime_type,
-                "paperless__has_archive_version":
+                "media_filename": doc.filename,
-                    os.path.isfile(doc.archive_path)
+                "has_archive_version": os.path.isfile(doc.archive_path),
+                "original_metadata": self.get_metadata(
+                    doc.source_path, doc.mime_type),
+                "archive_metadata": self.get_metadata(
+                    doc.archive_path, "application/pdf")
             })
         except Document.DoesNotExist:
             raise Http404()