graphql engine can not process graphql queries against OpenLink Virtuso´s graphql endpoint.

[E-Babkin]

OpenLink Virtuoso exposes a Graphql schema in a different format, without NON_NULL top-level type.

In the result exception is raised in a stand alone program, or inside the Apache Superset.

The details of that case are described also in Stackoverlfow:
https://stackoverflow.com/questions/78405538/how-to-achieve-compliance-between-graphql-in-virtuoso-and-python-graphql-db-api

[cancan101]

What issue are you running into when trying to use this library with the OpenLink Virtuoso API? If there is a stack trace, could you post it?

[E-Babkin]

Sure, here is the program

from sqlalchemy import create_engine
from sqlalchemy import text


#engine = create_engine('graphql://pet-library.moonhighway.com/')
#query = "select id, name from 'allPets?is_connection=0'"

# Virtuoso's hosted  GraphQL endpoint
engine = create_engine('graphql://linkeddata.uriburner.com/graphql')
query = "select name from 'Concepts?is_connection=0'"

with engine.connect() as connection:
    for row in connection.execute(text(query)):
        print(row)

And the stacktrace :

/home/PycharmProjects/pythonProject/.venv/bin/python /home/PycharmProjects/pythonProject/graphql_client.py 
/home/PycharmProjects/pythonProject/graphql_client.py:8: SADeprecationWarning: The dbapi() classmethod on dialect classes has been renamed to import_dbapi().  Implement an import_dbapi() classmethod directly on class <class 'graphqldb.dialect.APSWGraphQLDialect'> to remove this warning; the old .dbapi() classmethod may be maintained for backwards compatibility.
  engine = create_engine('graphql://linkeddata.uriburner.com/graphql')
Traceback (most recent call last):
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/shillelagh/backends/apsw/db.py", line 229, in execute
    self._cursor.execute(operation, parameters)
  File "src/cursor.c", line 959, in APSWCursor_execute.sqlite3_prepare_v3
apsw.SQLError: SQLError: no such table: Concepts?is_connection=0

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/PycharmProjects/pythonProject/graphql_client.py", line 21, in <module>
    for row in connection.execute(text(query)):
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1422, in execute
    return meth(
           ^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/sql/elements.py", line 514, in _execute_on_connection
    return connection._execute_clauseelement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1644, in _execute_clauseelement
    ret = self._execute_context(
          ^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1850, in _execute_context
    return self._exec_single_context(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1990, in _exec_single_context
    self._handle_dbapi_exception(
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 2360, in _handle_dbapi_exception
    raise exc_info[1].with_traceback(exc_info[2])
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/base.py", line 1971, in _exec_single_context
    self.dialect.do_execute(
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/sqlalchemy/engine/default.py", line 919, in do_execute
    cursor.execute(statement, parameters)
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/shillelagh/backends/apsw/db.py", line 87, in wrapper
    return method(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/shillelagh/backends/apsw/db.py", line 240, in execute
    self._create_table(uri)
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/shillelagh/backends/apsw/db.py", line 304, in _create_table
    self._cursor.execute(
  File "src/vtable.c", line 907, in VirtualTable.xCreate
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/shillelagh/backends/apsw/vt.py", line 294, in Create
    adapter = self.adapter(*deserialized_args)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/PycharmProjects/pythonProject/.venv/lib/python3.11/site-packages/graphqldb/adapter.py", line 419, in __init__
    raise ValueError("Unable to resolve item_container_type")
ValueError: Unable to resolve item_container_type

Process finished with exit code 1

[cancan101]

1. You should be indicating this is a non-Connection: query = "select name from 'Concepts?is_connection=0'"
2. You need the changes in this PR: Support uriburner's linkdata endpoint #377; however, I am not okay just merging that as is without adding some additional error reporting, etc.

[E-Babkin]

Ok, thank you for the response.
Indeed, the no-connection option should be used in that case.
I made changes in the original code and the stack trace.
Also, the statements in #377 correctly note needs to support IRI data type.
so, after including error reporting these fixes will be available in the main branch, will be ?

[cancan101]

I don't have the bandwidth to complete #377 and merge to main. That being said, you can use pip to install directly from the PR branch if you want to work with the functionality.