Can't connect to SQL Database Utility: Error building component SQLDatabase: can't load plugin: sqlalchemy.dialects:postgres

[antoremin]

Describe the bug I'm putting in a postgresql connection string and get an error: Error building component SQLDatabase: can't load plugin: sqlalchemy.dialects:postgres.

Browser and Version

• Browser Chrome
• Version 1.05

To Reproduce Steps to reproduce the behavior:

1. Make a new flow
2. Click on SQLDatabase utility
3. Put in postgresql URI connection string and click "run"
4. See error

Screenshots

Additional context If I'm not mistaken, sqlalchemy deprecated postgres and only allows postgresql dialect. Yet in Langflow SQLDatabase, SQLExecutor, etc, the postgresql URI is explicitly replaced with postgres:

    def clean_up_uri(self, uri: str) -> str:
        if uri.startswith("postgresql://"):
            uri = uri.replace("postgresql://", "postgres://")
        return uri.strip()

[dosubot[bot]]

Hey there, @antoremin! I'm here to help you with any bugs, questions, or contributions you might have. Let's tackle this together while we wait for a human maintainer.

To resolve the error "Error building component SQLDatabase: can't load plugin: sqlalchemy.dialects:postgres," you need to ensure that the PostgreSQL URI is correctly formatted. The clean_up_uri method in the SQLDatabaseComponent class replaces "postgresql://" with "postgres://", which is necessary because SQLAlchemy expects the URI to be in the format "postgres://".

Here is the relevant part of the code:

def clean_up_uri(self, uri: str) -> str:
    if uri.startswith("postgresql://"):
        uri = uri.replace("postgresql://", "postgres://")
    return uri.strip()

Make sure your URI is correctly formatted using this method before passing it to the SQLDatabase.from_uri method. This should resolve the error related to loading the PostgreSQL plugin.

Here is an example of how to use the SQLDatabaseComponent to build the SQLDatabase:

from langchain_experimental.sql.base import SQLDatabase

class SQLDatabaseComponent:
    def clean_up_uri(self, uri: str) -> str:
        if uri.startswith("postgresql://"):
            uri = uri.replace("postgresql://", "postgres://")
        return uri.strip()

    def build(self, uri: str) -> SQLDatabase:
        uri = self.clean_up_uri(uri)
        return SQLDatabase.from_uri(uri)

component = SQLDatabaseComponent()
uri = "postgresql://user:password@localhost/dbname"
database = component.build(uri)

This will ensure that the URI is cleaned up and correctly formatted, allowing the SQLDatabase utility to connect to the PostgreSQL database without encountering the plugin loading error ^[1][2].

To continue talking to Dosu, mention @dosu.

[carlosrcoelho]

Hi @antoremin ,

Do you need any assistance with this case? If not, please let us know if this issue can be closed.

[Alperemrehas]

Hi @antoremin ,

Do you need any assistance with this case? If not, please let us know if this issue can be closed.

Actually I was having the same error yesterday.

If I have time I could checked that, depending on best of my knowledge replace is not solving the issue anymore.

[carlosrcoelho]

@antoremin

I checked it out and the component seems outdated. It needs to be updated to the new model that the components are built on.

[Alperemrehas]

This solved my problem:

from langchain_experimental.sql.base import SQLDatabase
from langflow.interface.custom.custom_component import CustomComponent

class SQLDatabaseComponent(CustomComponent):
    display_name = "SQLDatabase"
    description = "SQL Database"

    def build_config(self):
        return {
            "uri": {"display_name": "URI", "info": "URI to the database."},
        }
#SQLAlchemy 1.4 removed the deprecated postgres dialect name, the name postgresql must be used instead now.
    def clean_up_uri(self, uri: str) -> str:
        if uri.startswith("postgres://"):
            uri = uri.replace("postgres://", "postgresql://")
        return uri.strip()

    def build(self, uri: str) -> SQLDatabase:
        uri = self.clean_up_uri(uri)
        return SQLDatabase.from_uri(uri)

[carlosrcoelho]

@Alperemrehas Thank you!

Fixed here: https://github.com/langflow-ai/langflow/pull/3292

[Alperemrehas]

@Alperemrehas Thank you!

Fixed here: #3292

Thank you @carlosrcoelho .