Error Creating Table with JSON Column

Environment details

OS type and version: Linux, Debian
Python version: Python 3.13.7
pip version: pip 25.3
sqlalchemy-bigquery version: 1.16.0

Steps to reproduce

Define a table with a JSON column
Try to create it with alembic, create_all or such

Code example

Table("tbl", MetaData(), Column("stuff", JSON()))

Stack trace

Traceback (most recent call last):
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 134, in _compiler_dispatch
    meth = getter(visitor)
AttributeError: 'BigQueryTypeCompiler' object has no attribute 'visit_JSON'. Did you mean: 'visit_BLOB'?

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 6769, in visit_create_table
    processed = self.process(
        create_column, first_pk=column.primary_key and not first_pk
    )
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 932, in process
    return obj._compiler_dispatch(self, **kwargs)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 138, in _compiler_dispatch
    return meth(self, **kw)  # type: ignore  # noqa: E501
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 6800, in visit_create_column
    text = self.get_column_specification(column, first_pk=first_pk)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/sqlalchemy_bigquery/base.py", line 665, in get_column_specification
    colspec = super(BigQueryDDLCompiler, self).get_column_specification(
        column, **kwargs
    )
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 7026, in get_column_specification
    + self.dialect.type_compiler_instance.process(
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        column.type, type_expression=column
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 977, in process
    return type_._compiler_dispatch(self, **kw)
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 136, in _compiler_dispatch
    return visitor.visit_unsupported_compilation(self, err, **kw)  # type: ignore  # noqa: E501
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 982, in visit_unsupported_compilation
    raise exc.UnsupportedCompilationError(self, element) from err
sqlalchemy.exc.UnsupportedCompilationError: Compiler <sqlalchemy_bigquery.base.BigQueryTypeCompiler object at 0x7f9e0285ae90> can't render element of type JSON (Background on this error at: https://sqlalche.me/e/20/l7de)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/runner.py", line 353, in from_call
    result: TResult | None = func()
                             ~~~~^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/runner.py", line 245, in <lambda>
    lambda: runtest_hook(item=item, **kwds),
            ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 512, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 167, in _multicall
    raise exception
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/logging.py", line 850, in pytest_runtest_call
    yield
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/capture.py", line 900, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/skipping.py", line 268, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 121, in _multicall
    res = hook_impl.function(*args)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/runner.py", line 179, in pytest_runtest_call
    item.runtest()
    ~~~~~~~~~~~~^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/python.py", line 1720, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_hooks.py", line 512, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 167, in _multicall
    raise exception
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/pluggy/_callers.py", line 121, in _multicall
    res = hook_impl.function(*args)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/_pytest/python.py", line 166, in pytest_pyfunc_call
    result = testfunction(**testargs)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/tests/unit/test_table_options.py", line 62, in test_table_with_json_columns
    setup_table(
    ~~~~~~~~~~~^
        faux_conn,
        ^^^^^^^^^^
        "some_table",
        ^^^^^^^^^^^^^
        sqlalchemy.Column("some_stuff", sqlalchemy.JSON),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/tests/unit/conftest.py", line 100, in setup_table
    metadata.create_all(connection.engine)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/schema.py", line 5928, in create_all
    bind._run_ddl_visitor(
    ~~~~~~~~~~~~~~~~~~~~~^
        ddl.SchemaGenerator, self, checkfirst=checkfirst, tables=tables
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 3252, in _run_ddl_visitor
    conn._run_ddl_visitor(visitorcallable, element, **kwargs)
    ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 2459, in _run_ddl_visitor
    ).traverse_single(element)
      ~~~~~~~~~~~~~~~^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 661, in traverse_single
    return meth(obj, **kw)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/ddl.py", line 984, in visit_metadata
    self.traverse_single(
    ~~~~~~~~~~~~~~~~~~~~^
        table,
        ^^^^^^
    ...<2 lines>...
        _is_metadata_operation=True,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 661, in traverse_single
    return meth(obj, **kw)
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/ddl.py", line 1022, in visit_table
    )._invoke_with(self.connection)
      ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/ddl.py", line 321, in _invoke_with
    return bind.execute(self)
           ~~~~~~~~~~~~^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 1419, in execute
    return meth(
        self,
        distilled_parameters,
        execution_options or NO_OPTIONS,
    )
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/ddl.py", line 187, in _execute_on_connection
    return connection._execute_ddl(
           ~~~~~~~~~~~~~~~~~~~~~~~^
        self, distilled_params, execution_options
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 1527, in _execute_ddl
    compiled = ddl.compile(
        dialect=dialect, schema_translate_map=schema_translate_map
    )
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/elements.py", line 311, in compile
    return self._compiler(dialect, **kw)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/ddl.py", line 76, in _compiler
    return dialect.ddl_compiler(dialect, self, **kw)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 886, in __init__
    self.string = self.process(self.statement, **compile_kwargs)
                  ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 932, in process
    return obj._compiler_dispatch(self, **kwargs)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/visitors.py", line 138, in _compiler_dispatch
    return meth(self, **kw)  # type: ignore  # noqa: E501
  File "/usr/local/google/home/waltaskew/src/python-bigquery-sqlalchemy/venv/lib/python3.13/site-packages/sqlalchemy/sql/compiler.py", line 6779, in visit_create_table
    raise exc.CompileError(
    ...<2 lines>...
    ) from ce
sqlalchemy.exc.CompileError: (in table 'some_table', column 'some_stuff'): Compiler <sqlalchemy_bigquery.base.BigQueryTypeCompiler object at 0x7f9e0285ae90> can't render element of type JSON

I have the same issue, is anyone reviewing googleapis/python-bigquery-sqlalchemy#1283? Would be very appreciated!

I've been doing this lil' hack while waiting for my PR to come in:

import sqlalchemy_bigquery

# Monkey-patch in support for JSON columns while we wait for this fix to be released:                                                                                                                                                                                                     
# https://github.com/googleapis/python-bigquery-sqlalchemy/pull/1283                                                                                                                                                                                                                      
sqlalchemy_bigquery.dialect.type_compiler.visit_JSON = lambda *args, **kwargs: "JSON"

This issue was moved from the following repo as part of the monorepo migration: googleapis/python-bigquery-sqlalchemy

fix: Support Creation of JSON columns

fix(sqlalchemy-bigquery): Support Creation of JSON columns (#16733)

Navigation Menu

Repository navigation

Error Creating Table with JSON Column #15761

Environment details

Steps to reproduce

Code example

Stack trace

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Error Creating Table with JSON Column #15761

Description

Environment details

Steps to reproduce

Code example

Stack trace

Activity

aebrahim commented on Dec 17, 2025

waltaskew commented on Dec 17, 2025

chalmerlowe commented on Mar 2, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions