Hello, I am trying to implement oop for a POC since some people at my organization prefer this. However, I am running into an error when using the output of a class method in another function downstream. I tried using the

make_python_type_usable_as_dagster_type

function to convert the pandas.core.frame.DataFrame class to dagster._core.definitions.composition.InvokedNodeOutputHandle but I'm having formatting the inputs correctly. This is the error I get when running the code below without trying to change the type to a dagster type.

dagster._core.errors.DagsterInvalidDefinitionError: In @job ga_fire, received invalid type <class 'pandas.core.frame.DataFrame'> for input "gw_claim" (at position 0) in op invocation "create_final". Must pass the output from previous node invocations or inputs to the composition function as inputs when invoking nodes during composition.

#@usable_as_dagster_type
class GW_claim_obj:
    
    #@property
    def __init__(self):
        host = "<http://vpce-0db7ab069278226a9-nmwg1dku.vpce-svc-004d858ae4cced757.us-west-2.vpce.amazonaws.com|vpce-0db7ab069278226a9-nmwg1dku.vpce-svc-004d858ae4cced757.us-west-2.vpce.amazonaws.com>"
        user = os.getenv("REDSHIFT_BDD_LOCAL_UID")
        pw = os.getenv("REDSHIFT_BDD_LOCAL_PWD")
        database = "bi_edw_db"    

        self.con = redshift_connector\
                .connect(
                  host=host,
                  database=database,
                  user=user,
                  password=pw
                  )
    
    #@property
    def create_gw_claim(self):
        #Code for Query Builder in SAS GA Fire Job
        qry = open("gw_claim.sql", "r").read()
        claim_dw_df = pd.read_sql(sql=qry, con=self.con)
        claim_dw_df['quarter'] = claim_dw_df['dateofloss'].dt.to_period('Q').dt.strftime('%Y-%q')
        return claim_dw_df

Here is my job configuration. The other functions are normal functions with @asset decorators.

@job
def ga_fire():
    gw_claim_obj = GW_claim_obj()
    gw_claim = gw_claim_obj.create_gw_claim()
    #make_python_type_usable_as_dagster_type(<class 'pandas.core.frame.DataFrame'>,  <class 'dagster._core.definitions.composition.InvokedNodeOutputHandle'>)
    cc_claim = create_cc_claim()
    final = create_final(gw_claim, cc_claim)
    upload_final(final)

Could I get some direction on how to implement class methods in dagster?

Hi Nathan, thanks for the question. In general the only thing you should have inside your jobs is op invocations.

usable_as_dagster_type

makes a class usable as a Dagster Type, not as an op. Assets also are not for use inside a

@job

-- it looks to me like you would learn a lot from going through our software-defined asset tutorial: https://docs.dagster.io/tutorial#intro-to-software-defined-assets

Hi Sean, thanks for the reply. I tried defining all my functions and my class method as ops, but I get an error from dagster not recognizing the self input in a class method shouldn't be required. I might've been asking the wrong question initially, does dagster support using class methods or should we only use function based programming?

Error 1: Missing required config entry "ops" at the root. Sample config for missing entry: {'ops': {'create_gw_claim': {'inputs': {'self': '<selector>'}}}}

You can use class methods as you might in any Python program, but not for ops. An op needs to be a plain function (no kind of method).