add safeguard for formatting errors (#708)

pygeoapi/api.py

@@ -52,6 +52,7 @@ from shapely.errors import WKTReadingError
 from shapely.wkt import loads as shapely_loads
 
 from pygeoapi import __version__, l10n
+from pygeoapi.formatter.base import FormatterSerializationError
 from pygeoapi.linked_data import (geojson2geojsonld, jsonldify,
                                   jsonldify_collection)
 from pygeoapi.log import setup_logger
@@ -1413,14 +1414,20 @@ class API:
             formatter = load_plugin('formatter',
                                     {'name': 'CSV', 'geom': True})
 
-            content = formatter.write(
-                data=content,
-                options={
-                    'provider_def': get_provider_by_type(
-                                        collections[dataset]['providers'],
-                                        'feature')
-                }
-            )
+            try:
+                content = formatter.write(
+                    data=content,
+                    options={
+                        'provider_def': get_provider_by_type(
+                                            collections[dataset]['providers'],
+                                            'feature')
+                    }
+                )
+            except FormatterSerializationError as err:
+                LOGGER.error(err)
+                msg = 'Error serializing output'
+                return self.get_exception(
+                    500, headers, request.format, 'NoApplicableCode', msg)
 
             headers['Content-Type'] = '{}; charset={}'.format(
                 formatter.mimetype, self.config['server']['encoding'])

pygeoapi/formatter/base.py

@@ -65,3 +65,13 @@ class BaseFormatter:
 
     def __repr__(self):
         return '<BaseFormatter> {}'.format(self.name)
+
+
+class FormatterGenericError(Exception):
+    """formatter generic error"""
+    pass
+
+
+class FormatterSerializationError(FormatterGenericError):
+    """formatter serialization error"""
+    pass

pygeoapi/formatter/csv_.py

@@ -32,7 +32,7 @@ import logging
 
 import unicodecsv as csv
 
-from pygeoapi.formatter.base import BaseFormatter
+from pygeoapi.formatter.base import BaseFormatter, FormatterSerializationError
 
 LOGGER = logging.getLogger(__name__)
 
@@ -85,17 +85,22 @@ class CSVFormatter(BaseFormatter):
 
         LOGGER.debug('CSV fields: {}'.format(fields))
 
-        output = io.BytesIO()
-        writer = csv.DictWriter(output, fields)
-        writer.writeheader()
+        try:
+            output = io.BytesIO()
+            writer = csv.DictWriter(output, fields)
+            writer.writeheader()
+
+            for feature in data['features']:
+                fp = feature['properties']
+                if is_point:
+                    fp['x'] = feature['geometry']['coordinates'][0]
+                    fp['y'] = feature['geometry']['coordinates'][1]
+                LOGGER.debug(fp)
+                writer.writerow(fp)
+        except ValueError as err:
+            LOGGER.error(err)
+            raise FormatterSerializationError('Error writing CSV output')
 
-        for feature in data['features']:
-            fp = feature['properties']
-            if is_point:
-                fp['x'] = feature['geometry']['coordinates'][0]
-                fp['y'] = feature['geometry']['coordinates'][1]
-            LOGGER.debug(fp)
-            writer.writerow(fp)
         return output.getvalue()
 
     def __repr__(self):