# Add\_table\_asset fails with "int object is not iterable" on SQLAlchemy 1.3.24 + Python 3.9.19 (postgres)

**URL:** <https://discourse.greatexpectations.io/t/add-table-asset-fails-with-int-object-is-not-iterable-on-sqlalchemy-1-3-24-python-3-9-19-postgres/1750>\
**Category:** GX Core Support\
**Created:** [May 28, 2024, 11:33am UTC](https://discourse.greatexpectations.io/t/add-table-asset-fails-with-int-object-is-not-iterable-on-sqlalchemy-1-3-24-python-3-9-19-postgres/1750 "2024-05-28T11:33:05Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tm\_bjastrzebski](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@tm\_bjastrzebski](https://discourse.greatexpectations.io/u/tm_bjastrzebski)\
**Post date:** [May 28, 2024, 11:33am UTC](https://discourse.greatexpectations.io/t/add-table-asset-fails-with-int-object-is-not-iterable-on-sqlalchemy-1-3-24-python-3-9-19-postgres/1750/1 "2024-05-28T11:33:05Z")

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Hello GX community!

**tl;dr:** should GX work with Postgres (15.1) and SQLAlchemy==1.3.24?

I’m currently doing research into multiple data observability/data integrity tools at work; GX is obviously one of them.

I’m going step-by-step through [the “SQL” tutorial](https://docs.greatexpectations.io/docs/oss/get_started/get_started_with_gx_and_sql).

For context, the rest of the post will refer to a `test` table in the `postgres` database in the “system” Postgres.  
I created it to make sure that it isn’t a problem with a dockerized postgres instance that GX will actually connect to (and which I initially used).  
The issue described later occurs with both, which leads me to think that this isn’t a problem with Postgres nor the tables. Also, it works with SQLAlchemy \>= 2.0 😃

**Steps to reproduce** :

Setting up the environment:

```auto
mkdir delete_me
cd delete_me
virtualenv .venv -p python3.9
. .venv/bin/activate
pip install great-expectations==0.18.14
pip install sqlalchemy==1.3.24
pip install psycopg2==2.9.9

```

Let’s go through the tutorial then! In python REPL:

```auto
import great_expectations as gx

path_to_dir = "./contexts"
context = gx.get_context(project_root_dir=path_to_dir)

# Connection string confirmed to work by running psql postgresql://Work@localhost:5432/postgres in system shell
connection_string = "postgresql://Work@localhost:5432/postgres"
local = context.sources.add_postgres(name="local", connection_string=connection_string)

# Works until here
local.add_table_asset(name="test", table_name="test") # Fails here

```

Stacktrace as follows:

```auto
Traceback (most recent call last):
  File "~/delete_me/.venv/lib/python3.9/site-packages/great_expectations/datasource/fluent/sql_datasource.py", line 928, in test_connection
    connection.execute(sa.select(1, table).limit(1))
  File "<string>", line 2, in select
  File "<string>", line 2, in __init__
  File "~/delete_me/.venv/lib/python3.9/site-packages/sqlalchemy/util/deprecations.py", line 139, in warned
    return fn(*args, **kwargs)
  File "~/delete_me/.venv/lib/python3.9/site-packages/sqlalchemy/sql/selectable.py", line 3117, in __init__
    for c in columns:
TypeError: 'int' object is not iterable

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

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "~/delete_me/.venv/lib/python3.9/site-packages/great_expectations/datasource/fluent/sql_datasource.py", line 1185, in add_table_asset
    return self._add_asset(asset)
  File "~/delete_me/.venv/lib/python3.9/site-packages/great_expectations/datasource/fluent/interfaces.py", line 553, in _add_asset
    asset.test_connection()
  File "~/delete_me/.venv/lib/python3.9/site-packages/great_expectations/datasource/fluent/sql_datasource.py", line 933, in test_connection
    raise TestConnectionError(
great_expectations.datasource.fluent.interfaces.TestConnectionError: Attempt to connect to table: test failed because the test query failed. Ensure the table exists and the user has access to select data from the table: 'int' object is not iterable

```

I have set a `breakpoint()` in `delete_me/.venv/lib/python3.9/site-packages/sqlalchemy/sql/selectable.py` ([link to github](https://github.com/sqlalchemy/sqlalchemy/blob/rel_1_3_24/lib/sqlalchemy/sql/selectable.py#L3115-L3123)) to find out that:

1. argument/variable “columns” should be either a `ColumnElement`, or a `FromClause` (typically `Table` or `Alias`, to be extracted to a collection of `ColumnElement`s); also acceptable are `TextClause` or ORM-mapped classes (from docstring).

2. `columns` is a list containing only one element of type `sqlalchemy.sql.elements.Cast` (repr: `CAST('test plain returns' AS VARCHAR(60))`) - which as far as I can tell is not what should be passed.

I tried replicating the same steps while on SQLAlchemy\>=2.0 and it worked without any issues.

Which leads us back to the initial question: should GX work with SQLAlchemy==1.3.24 and Postgres? I tried: googling for an answer, looked for one in the docs, searched open and closed GitHub issues, and on this forum – but I was unable to find anything useful; hell, it even seems that nobody ran into a similar issue earlier, which gives me pause.

System/versions info:

- Python 3.9.19
- great-expectations==0.18.14
- SQLAlchemy==1.3.24
- psycopg2==2.9.9
- PostgreSQL 15.1 on x86\_64-apple-darwin20.6.0, compiled by Apple clang version 12.0.0 (clang-1200.0.32.29), 64-bit
- MacOS Monterey 12.5 (Apple Silicon/M1 Pro chip)

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**Author:** ![tm\_bjastrzebski](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@tm\_bjastrzebski](https://discourse.greatexpectations.io/u/tm_bjastrzebski)\
**Post date:** [June 7, 2024, 8:22am UTC](https://discourse.greatexpectations.io/t/add-table-asset-fails-with-int-object-is-not-iterable-on-sqlalchemy-1-3-24-python-3-9-19-postgres/1750/2 "2024-06-07T08:22:30Z")

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Just to answer my own question: GX doesn’t work with SQLAlchemy \< 2 🙂