@Scout how to create a resource with pyodbc

To create a resource with

pyodbc

in Dagster, you would typically define a Python class that inherits from

ConfigurableResource

. This class would establish a connection to your database using

pyodbc

and provide methods to interact with the database. Here's a step-by-step guide based on the documentation: 1. Define the Resource Class: Create a new Python class that inherits from

ConfigurableResource

. This class will encapsulate the logic for connecting to the database using

pyodbc

. 2. Configure the Resource: Define the configuration schema for your resource. This typically includes the database connection parameters such as the server, database name, username, password, and driver. 3. Implement Connection Methods: Implement methods to establish and close the database connection. You might also want to implement methods to execute queries or perform other database operations. 4. Use Context Managers: Optionally, you can use context managers to ensure that connections are properly closed after use. 5. Register the Resource: Add the resource to your Dagster repository so that it can be used by your assets or ops. Here is an example of how you might define a

pyodbc

resource in Dagster, based on the pattern shown in the documentation for creating resources:

python
from dagster import ConfigurableResource, InitResourceContext
import pyodbc

class PyODBCResource(ConfigurableResource):
    server: str
    database: str
    username: str
    password: str
    driver: str

    def __init__(self, context: InitResourceContext):
        self.server = context.resource_config['server']
        self.database = context.resource_config['database']
        self.username = context.resource_config['username']
        self.password = context.resource_config['password']
        self.driver = context.resource_config['driver']

    def connect(self):
        connection_string = f"DRIVER={self.driver};SERVER={self.server};DATABASE={self.database};UID={self.username};PWD={self.password}"
        return pyodbc.connect(connection_string)

    def execute_query(self, query):
        with self.connect() as conn:
            cursor = conn.cursor()
            cursor.execute(query)
            return cursor.fetchall()

# Usage in an asset
@asset(required_resource_keys={"pyodbc_resource"})
def my_asset(context):
    query_result = context.resources.pyodbc_resource.execute_query("SELECT * FROM my_table")
    # Do something with query_result

In this example, the

PyODBCResource

class is a

ConfigurableResource

that uses

pyodbc

to connect to a database. The

connect

method creates a new connection using the provided configuration, and the

execute_query

method executes a given SQL query. Please note that this is a simplified example, a

Why is def __init__(self, context: InitResourceContext) needed?

The

__init__

method with the

context: InitResourceContext

parameter is not strictly necessary when defining a resource in Dagster using the

ConfigurableResource

base class. My previous example was incorrect in that regard, and I apologize for the confusion. In Dagster, when you define a resource using the

@resource

decorator, you typically provide an initialization function that takes an

InitResourceContext

object. This context object contains all the information needed to initialize the resource, including configuration data and logging. Here's a corrected example of how you might define a

pyodbc

resource in Dagster:

python
from dagster import resource, InitResourceContext
import pyodbc

@resource
def pyodbc_resource(init_context: InitResourceContext):
    server = init_context.resource_config['server']
    database = init_context.resource_config['database']
    username = init_context.resource_config['username']
    password = init_context.resource_config['password']
    driver = init_context.resource_config['driver']
    
    def connect():
        connection_string = f"DRIVER={driver};SERVER={server};DATABASE={database};UID={username};PWD={password}"
        return pyodbc.connect(connection_string)
    
    return connect

# Usage in an asset
@asset(required_resource_keys={"pyodbc_resource"})
def my_asset(context):
    connect = context.resources.pyodbc_resource
    with connect() as conn:
        cursor = conn.cursor()
        cursor.execute("SELECT * FROM my_table")
        query_result = cursor.fetchall()
    # Do something with query_result

In this example,

pyodbc_resource

is a function decorated with

@resource

that takes

InitResourceContext

as an argument. The function uses the configuration provided in the

InitResourceContext

to create a connection string and returns a

connect

function that establishes a connection to the database when called. The

InitResourceContext

is provided by Dagster during the execution of a pipeline and contains the configuration and other context needed to initialize the resource. It is a way for Dagster to pass runtime information to the resource at initialization time. Resources | Dagster button Dagster Docs button Allow to set default value for

EnvVar

button Nested resource dependencies do not work... button Thank you for your feedback!

@Scout But how would I formulate it as configurableresource

In Dagster, if you want to define a resource as a

ConfigurableResource

, you would subclass

ConfigurableResource

and define the configuration schema using class attributes. The

ConfigurableResource

base class allows you to define resources with structured configuration in a more declarative way, using Python class syntax. Here's an example of how you might define a

pyodbc

resource as a `ConfigurableResource`:

python from dagster import ConfigurableResource import pyodbc  class PyODBCResource(ConfigurableResource):     server: str     database: str     username: str     password: str     driver: str      def connect(self):         connection_string = f"DRIVER={self.driver};SERVER={self.server};DATABASE={self.database};UID={self.username};PWD={self.password}"         return pyodbc.connect(connection_string)  # Usage in an asset @asset(required_resource_keys={"pyodbc_resource"}) def my_asset(context):     connect = context.resources.pyodbc_resource.connect     with connect() as conn:         cursor = conn.cursor()         cursor.execute("SELECT * FROM my_table")         query_result = cursor.fetchall()     # Do something with query_result

In this example,

PyODBCResource

is a subclass of

ConfigurableResource

with class attributes that define the configuration schema. The

connect

method uses these attributes to create a connection string and establish a connection to the database. When you use this resource in an asset, you would provide the configuration for the resource in your Dagster repository definition, like so:

python from dagster import asset, repository, define_asset_job  @repository def my_repository():     return [         my_asset,         define_asset_job('my_asset_job', selection=[my_asset]),         {             "resources": {                 "pyodbc_resource": PyODBCResource(                     server="my_server",                     database="my_database",                     username="my_username",                     password="my_password",                     driver="my_driver",                 )             }         }     ]

In this repository definition, you instantiate the

PyODBCResource

with the necessary configuration parameters. When the asset

my_asset

is executed, it will use the configured

pyodbc_resource

to connect to the database and perform the query.