Assure better error messages when parsing word documents with jinja syntax.

I also have a pull request into the folks that run the python docx library to improve their error messages that we depend on here.

Pipfile.lock

@@ -1238,7 +1238,7 @@
         },
         "spiffworkflow": {
             "git": "https://github.com/sartography/SpiffWorkflow",
-            "ref": "e79a3da7a489d12ed8b4666d1b01d9a4a328ba6d"
+            "ref": "9b5b99fd7b1dac19586fe78026d1604f9f8a7e26"
         },
         "sqlalchemy": {
             "hashes": [

crc/api/common.py

@@ -13,7 +13,8 @@ import sentry_sdk
 
 class ApiError(Exception):
     def __init__(self, code, message, status_code=400,
-                 file_name="", task_id="", task_name="", tag="", task_data=None, error_type="", line_number=0,  offset=0):
+                 file_name="", task_id="", task_name="", tag="",
+                 task_data=None, error_type="", error_line="", line_number=0,  offset=0):
         if task_data is None:
             task_data = {}
         self.status_code = status_code
@@ -27,6 +28,7 @@ class ApiError(Exception):
         self.line_number = line_number
         self.offset = offset
         self.error_type = error_type
+        self.error_line = error_line
         if hasattr(g, 'user'):
             user = g.user.uid
         else:

crc/scripts/complete_template.py

@@ -1,10 +1,7 @@
-import copy
 import re
 from io import BytesIO
 
-import jinja2
-from docx.shared import Inches
-from docxtpl import DocxTemplate, Listing, InlineImage
+from SpiffWorkflow.exceptions import WorkflowTaskExecException
 
 from crc import session
 from crc.api.common import ApiError
@@ -78,7 +75,14 @@ Takes two arguments:
         else:
             image_file_data = None
 
-        return JinjaService().make_template(BytesIO(file_data_model.data), task.data, image_file_data)
+        try:
+            return JinjaService().make_template(BytesIO(file_data_model.data), task.data, image_file_data)
+        except ApiError as ae:
+            # In some cases we want to provide a very specific error, that does not get obscured when going
+            # through the python expression engine. We can do that by throwing a WorkflowTaskExecException,
+            # which the expression engine should just pass through.
+            raise WorkflowTaskExecException(task, ae.message, exception=ae, line_number=ae.line_number,
+                                            error_line=ae.error_line)
 
     def get_image_file_data(self, fields_str, task):
         image_file_data = []

crc/services/jinja_service.py

@@ -1,10 +1,16 @@
+import re
+import sys
+import traceback
+
 from docx.shared import Inches
 from docxtpl import DocxTemplate, Listing, InlineImage
 from io import BytesIO
-from jinja2 import Environment, DictLoader
+from jinja2 import Environment, DictLoader, TemplateSyntaxError
 
 import copy
 
+from crc.api.common import ApiError
+
 
 class JinjaService:
     """Service for Jinja2 templates.
@@ -49,8 +55,30 @@ Cool Right?
 
         try:
             doc.render(doc_context, jinja_env)
-        except Exception as e:
-            print(e)
+        except TemplateSyntaxError as tse:
+            line_number = tse.lineno
+
+            # the doc renderer code is trying to give context, returning 3 lines
+            # before and after the error if possible.  The can result in a lot of
+            # garbage, too much to send back.  Sometimes the line itself is too large.
+            # Just trying to get something sensible if possible.
+            context = list(tse.docx_context)
+            if len(context) == 1: # It just sent us the whole damn thing back.  Useless.
+                error_line = "Unable to determine location of error in the word document. Opening and Saving the " \
+                             "template in LibreOffice may fix this problem."
+            elif len(context) == 7:
+                error_line = context[3]
+            else:
+                error_line = ", ".join(context)
+
+            # If the bloodly thing is still stupid long, try grabbing the middle 200
+            # characters.
+            if len(error_line) > 500:
+                offset = int(len(error_line)/2 - 100)
+                error_line = "Error occurred near:  " + error_line[offset: -offset]
+
+            raise ApiError(code="template_error", message="Word Document creation error : %s" % str(tse),
+                           line_number=line_number, error_line=error_line)
         target_stream = BytesIO()
         doc.save(target_stream)
         target_stream.seek(0)  # move to the beginning of the stream.

tests/test_jinja_service.py

@@ -1,8 +1,15 @@
+import os
+from io import BytesIO
+
+from lxml import etree
+
 from tests.base_test import BaseTest
 from crc.services.workflow_processor import WorkflowProcessor
 from crc.services.workflow_service import WorkflowService
+from crc.services.jinja_service import JinjaService
+from crc.api.common import ApiError
 
-from crc import mail
+from crc import mail, app
 
 import json
 
@@ -50,8 +57,26 @@ class TestJinjaService(BaseTest):
         self.assert_success(rv)
         self.assertIn("Hello World", rv.get_data(as_text=True))
 
-    def test_jinja_service_documents(self):
-        pass
+    def test_jinja_service_word_documents(self):
+        filepath = os.path.join(app.root_path, '..', 'tests', 'data', 'template.docx')
+        with open(filepath, 'rb') as myfile:
+            file_data = BytesIO(myfile.read())
+        context = {'title': 'My Title', 'my_list': ["a", "b", "c"], 'show_table': True}
+        result = JinjaService().make_template(file_data, context)
+        self.assertIsNotNone(result)  # Not a lot we can do here, just assure there is not an error.
+
+    def test_jinja_service_word_document_errors_are_sensible(self):
+        filepath = os.path.join(app.root_path, '..', 'tests', 'data', 'template_error.docx')
+        with open(filepath, 'rb') as myfile:
+            file_data = BytesIO(myfile.read())
+        context = {'title': 'My Title', 'my_list': ["a", "b", "c"], 'show_table': True}
+        with self.assertRaises(ApiError) as ae:
+            result = JinjaService().make_template(file_data, context)
+        self.assertIn('{{% no_such_variable_error ! @ __ %}}', ae.exception.error_line)
+        self.assertEquals("Word Document creation error : unexpected '%'", ae.exception.message)
+        self.assertEquals(14, ae.exception.line_number)
+
+
 
     def test_jinja_service_properties(self):
         pass