SQLAlchemy NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:spanner - sqlalchemy

Question

Problem
We're trying to connect to Cloud Spanner via SQLAlchemy version 1.3.23 and python-spanner-sqlalchemy. Using Poetry for dependency management, sqlalchemy-spanner has been added like so (this is how the project was set up):
sqlalchemy = "~1.3"
sqlalchemy-spanner = { git="https://github.com/cloudspannerecosystem/python-spanner-sqlalchemy.git", tag="v0.1.0" }
When create_engine is called with
create_engine("spanner:///projects/my-project/instances/my-instance/databases/my-db")
I get the following error
class 'sqlalchemy.exc.NoSuchModuleError'>", "NoSuchModuleError(\"Can't load plugin: sqlalchemy.dialects:spanner\")
Attempts
Registry
I've tried adding (as seen in the conftest.py file in the python-spanner-sqlalchemy test package)
from sqlalchemy.dialects import registry
registry.register("spanner", "google.cloud.sqlalchemy_spanner", "SpannerDialect")
before create_engine is called, which leads to the following error:
class 'ModuleNotFoundError'>", "ModuleNotFoundError(\"No module named 'google.cloud.sqlalchemy_spanner'\")
This makes me think that the plugin dialect has not been correctly added since, in line 49 of setup.py, the connection for the dialect is made:
entry_points={
"sqlalchemy.dialects": [
"spanner = google.cloud.sqlalchemy_spanner:SpannerDialect"
]
},
Installing via python setup.py install
In the README for the spanner project, it says to clone the repo and install via python setup.py install. I performed this step, but am unsure how to import this into my current project or make my project aware of this library. I've never manually installed python packages before so, if anyone can provide any help here, I'd appreciate it.
What I did try:
install the library as per above
try to add the dependency via poetry : poetry add sqlalchemy-spanner. Got Could not find a matching version of package sqlalchemy-spanner
try to locate the library via pip : pip install sqlalchemy-spanner== which usually lists available package versions.
I'm not sure that either of the last 2 bullets actually check a local installation of a package. Not even really sure what I'm talking about here.
Update
So I was able to install the local version of python-spanner-sqlalchemy by using pip install /path/to/project, which works, but still having the same issues with loading the dialect.
I added an import for SpannerDialect in the code (in the Registry section) above with from google.cloud.sqlalchemy_spanner import SpannerDialect. PyCharm auto-completed this for me which indicates to me that the package is successfully installed and available. But I receive the ModuleNotFoundError for google.cloud.sqlalchemy_spanner when running.
I ran python in my project root directory and, from the repl, imported SpannerDialect with no errors.
Solution
To clarify, the solution #larkee provided worked regarding the updated repository URL.
As a note, we recently moved the repo from cloudspannerecosystem/python-spanner-sqlalchemy to googleapis/python-spanner-sqlalchemy.
I clarified why that worked in the comments to their answer
I have not tested the answer from #neondot42, but I have seen this brought up as well, so take a look there if you're having the same issue.

Answer 1

sorry for the late response. I was recently struggling with a similar problem. Sqlalchemy was unable to load the spanner dialect. I tried uninstalling and installing different versions with pip but nothing seemed to work.
At the end what did the trick was specifying the "driver" part of the database URL as "spanner" too. So the final URL looked like this:
spanner+spanner:///projects/project-id/instances/instance-id/databases/database-id
I am not entirely sure of why this appeared to be the solution for me, as all the documentation I could find on Google's end just showed that you could use only the "spanner:///..." to connect. Also I am not familiar with the inner workings of sqlalchemy and how it should detect other installed dialects. However, I hope this solution can help someone else.

Answer 2

I was able to replicate the error you are seeing by installing sqlalchemy but not having sqlalchemy-spanner installed at all:
pip install sqlalchemy==1.3
pip uninstall sqlalchemy-spanner
>>> from sqlalchemy import create_engine
>>> engine = create_engine(<url>)
sqlalchemy.exc.NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:spanner
After I install sqlalchemy-spanner I am able to use SQLAlchemy without issue:
pip install git+git://github.com/googleapis/python-spanner-sqlalchemy.git#v0.1.0
>>> from sqlalchemy import create_engine, MetaData, Table, Column, Integer, String, inspect
>>> engine = create_engine(<url>)
>>> metadata = MetaData(bind=engine)
>>> table = Table(
... "TestTable",
... metadata,
... Column("user_id", Integer, primary_key=True),
... Column("user_name", String(16), nullable=False),
... )
>>> table.create()
>>> inspect(engine).get_table_names()
['TestTable']
>>>
Based on this, I think the issue is that sqlalchemy-spanner is not being installed. Unfortunately, I'm not familiar with Poetry for dependency management so I'm not sure exactly what is going wrong. As a note, we recently moved the repo from cloudspannerecosystem/python-spanner-sqlalchemy to googleapis/python-spanner-sqlalchemy. I am able to use either for the pip command but perhaps Poetry requires the newer one?