Merge pull request #4159 from alphagov/catch-missing-letter

Catch error if letter does not exist on send

app/main/views/uploads.py

@@ -7,7 +7,6 @@ from functools import partial
 from io import BytesIO
 from zipfile import BadZipFile
 
-from botocore.exceptions import ClientError
 from flask import (
     abort,
     current_app,
@@ -39,6 +38,7 @@ from app.main import main
 from app.main.forms import CsvUploadForm, LetterUploadPostageForm, PDFUploadForm
 from app.models.contact_list import ContactList
 from app.s3_client.s3_letter_upload_client import (
+    LetterNotFoundError,
     backup_original_letter_to_s3,
     get_letter_metadata,
     get_letter_pdf_and_metadata,
@@ -267,17 +267,18 @@ def uploaded_letter_preview(service_id, file_id):
 
     try:
         metadata = get_letter_metadata(service_id, file_id)
-    except ClientError as e:
-        # if the file's not there, it's probably because we've already created the notification and the letter has been
-        # moved to the normal letters-pdf bucket. So lets just bounce out to the notification page
-        if e.response['Error']['Code'] == 'NoSuchKey':
-            return redirect(url_for(
-                '.view_notification',
-                service_id=service_id,
-                notification_id=file_id,
-            ))
-        else:
-            raise
+    except LetterNotFoundError as e:
+        current_app.logger.warning(e)
+
+        # If the file is missing it could be because this is a duplicate
+        # request, the notification already exists and the file has been
+        # moved to a different bucket. Note that the ID of a precompiled
+        # notification is always set to the file_id.
+        return redirect(url_for(
+            '.view_notification',
+            service_id=service_id,
+            notification_id=file_id,
+        ))
 
     original_filename = metadata.get('filename')
     page_count = metadata.get('page_count')
@@ -352,7 +353,20 @@ def send_uploaded_letter(service_id, file_id):
     if not current_service.has_permission('letter'):
         abort(403)
 
-    metadata = get_letter_metadata(service_id, file_id)
+    try:
+        metadata = get_letter_metadata(service_id, file_id)
+    except LetterNotFoundError as e:
+        current_app.logger.error(e)
+
+        # If the file is missing it could be because this is a duplicate
+        # request, the notification already exists and the file has been
+        # moved to a different bucket. Note that the ID of a precompiled
+        # notification is always set to the file_id.
+        return redirect(url_for(
+            '.view_notification',
+            service_id=service_id,
+            notification_id=file_id,
+        ))
 
     if metadata.get('status') != 'valid':
         abort(403)

app/s3_client/s3_letter_upload_client.py

@@ -1,11 +1,16 @@
 import json
 import urllib
 
+import botocore
 from boto3 import resource
 from flask import current_app
 from notifications_utils.s3 import s3upload as utils_s3upload
 
 
+class LetterNotFoundError(Exception):
+    pass
+
+
 def get_transient_letter_file_location(service_id, upload_id):
     return 'service-{}/{}.pdf'.format(service_id, upload_id)
 
@@ -69,19 +74,24 @@ class LetterMetadata:
         return value
 
 
+def get_letter_s3_object(service_id, file_id):
+    try:
+        file_location = get_transient_letter_file_location(service_id, file_id)
+        s3 = resource('s3')
+        return s3.Object(current_app.config['TRANSIENT_UPLOADED_LETTERS'], file_location).get()
+    except botocore.exceptions.ClientError as e:
+        if e.response['Error']['Code'] == 'NoSuchKey':
+            raise LetterNotFoundError(f'Letter not found for service {service_id} and file {file_id}')
+
+        raise
+
+
 def get_letter_pdf_and_metadata(service_id, file_id):
-    file_location = get_transient_letter_file_location(service_id, file_id)
-    s3 = resource('s3')
-    s3_object = s3.Object(current_app.config['TRANSIENT_UPLOADED_LETTERS'], file_location).get()
-
+    s3_object = get_letter_s3_object(service_id, file_id)
     pdf = s3_object['Body'].read()
-
     return pdf, LetterMetadata(s3_object['Metadata'])
 
 
 def get_letter_metadata(service_id, file_id):
-    file_location = get_transient_letter_file_location(service_id, file_id)
-    s3 = resource('s3')
-    s3_object = s3.Object(current_app.config['TRANSIENT_UPLOADED_LETTERS'], file_location).get()
-
+    s3_object = get_letter_s3_object(service_id, file_id)
     return LetterMetadata(s3_object['Metadata'])