Error when trying to open a db query

[DentaCool]

VSCODE: "Invalid query argument. Extected string, instead got object"

I also added the log of the object itself to the throw via vim:

"Invalid query argument. Extected string, instead got object: null"

UPD: FRAME: file 'python3.9/site-packages/django/db/models/sql/compiler.py', line 1161, code execute_sql>

def execute_sql(self, result_type=MULTI, chunked_fetch=False, chunk_size=GET_ITERATOR_CHUNK_SIZE):
        result_type = result_type or NO_RESULTS
        try:
            sql, params = self.as_sql()
            if not sql:
                raise EmptyResultSet
        except EmptyResultSet:
            if result_type == MULTI:
                return iter([])
            else:
                return

UPD 2:

from psqlextra.query import PostgresQuerySet

[wilhelmklopp]

@LilyFoote any ideas here?

Possibly we don't support PostgresQuerySet?

@DentaCool do you use PostgresQuerySet directly? Does the issue happen even when you don't use it?

[LilyFoote]

Hard to say for sure without looking closely myself, but I wonder if we're just recording the query as null because we can't introspect it as something more useful.

@DentaCool Can you share the code that's triggering this when run with Kolo? Ideally a minimised example, so there's not too much code to work with, but I'll take what you can get.

[DentaCool]

class SQLQueryFilter:
  def process(
          self,
          frame: types.FrameType,
          event: str,
          arg: Any,
          call_frames: List[Tuple[types.FrameType, str]],
      ):
      # ...
        try:
            sql = frame.f_locals["sql"]
            params = frame.f_locals["params"]
        except KeyError:
            query_template = None
            query = None
        # ...

django/db/models/sql/compiler.py

def execute_sql():
        try:
            sql, params = self.as_sql()
            if not sql:
                raise EmptyResultSet
        except EmptyResultSet:
            if result_type == MULTI:
                return iter([])

this function fails with EmptyResultSet and returns iter([]). Thus

sql = frame.f_locals["sql"]
params = frame.f_locals["params"]

also fails with a KeyError and we will get

{
    "database": "postgres",
    "query": null,
    "query_template": null,
    "query_data": "<list_iterator object at 0x00B99F28>",
    "type": "end_sql_query"
}

At the moment, I'm just hardcoded fake query_template, query and query_data at KeyError. I will try to find more information and a solution as soon as I have time

[LilyFoote]

That's very interesting! Do you know which queryset in your code ends up with the EmptyResultSet exception?

[DentaCool]

from psqlextra.manager import PostgresManager, PostgresQuerySet

class SomeModelQuerySet(PostgresQuerySet):
    """Some query logic"""

class SomeModelManager(PostgresManager):
    def get_queryset(self):
        return SomeModelQuerySet(self.model, using=self._db)

class SomeModel(Model):
    # some fields and relations
    objects = SomeModelManager()

qs = SomeModel.objects.filter(some_relation=some_relation, other_field__in=[1,2,3]).prefetch_related('other_relation')

some_mapper = {instance.pk: some_func(instance)  for instance in qs}

Here is the code that was executed (as far as I remember). I will try to provide more detailed information after 13:00 Kyiv time.

Perhaps it would be nice to create a repository for the python library in future so that it is possible to contribute code

[LilyFoote]

Thanks! I'll look into that properly tomorrow.

[LilyFoote]

Looks like this is caused by Model.objects.none() or similar. In that case, there isn't a query to record, so Kolo stores null instead. I think this is something we need to handle better in VSCode.

[LilyFoote]

@wilhelmklopp ~Actually, we could just ignore this case on the python side.~ I'm not sure if it's valuable to display empty queries like this.

Edit: Actually, I think we need to emit the end frame in this case, since we can't detect we're in the empty queryset case when processing the start frame, so we can't drop both.

[wilhelmklopp]

👋 @DentaCool the latest version of the VSCode extension (2.8.1) includes the fix for this :)