Empty filter causes server error

[louise-davies]

Sending a request with the filter set to empty object (filter={}) causes the server to error and return a 500 error. Although best practice in the front end should be to not set this property if filters aren't applied - it probably shouldn't break the API either.

Traceback (most recent call last):
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask_restful\__init__.py", line 269, in error_router
    return original_handler(e)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\_compat.py", line 34, in reraise
    raise value.with_traceback(tb)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask_restful\__init__.py", line 269, in error_router
    return original_handler(e)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\_compat.py", line 34, in reraise
    raise value.with_traceback(tb)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask_restful\__init__.py", line 458, in wrapper
    resp = resource(*args, **kwargs)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask\views.py", line 88, in view
    return self.dispatch_request(*args, **kwargs)
  File "C:\Users\mnf98541\anaconda3\lib\site-packages\flask_restful\__init__.py", line 573, in dispatch_request
    resp = meth(*args, **kwargs)
  File "C:\code\datagateway-api\common\helpers.py", line 34, in wrapper_requires_session
    return method(*args, **kwargs)
  File "C:\code\datagateway-api\common\helpers.py", line 54, in wrapper_gets_records
    return method(*args, **kwargs)
  File "C:\code\datagateway-api\src\resources\entities\investigations_endpoints.py", line 14, in get
    return get_rows_by_filter(INVESTIGATION, get_filters_from_query_string()), 200
  File "C:\code\datagateway-api\common\database_helpers.py", line 127, in get_rows_by_filter
    if list(filter)[0].lower() == "where":
IndexError: list index out of range

[keiranjprice101]

@louise-davies What would be the best response in this event, 400 or just an unfiltered get all?

[louise-davies]

@keiranjprice101 In my opinion unfiltered get all - an empty set of filters is valid in the sense that we're asking for data with explicitly no filters applied. Essentially, ?filter={} should be ignored and treated the same not having a filter param at all