OK this looks like an easy one to fix :)

You can't use `params` as a param in an operator.  It's already used in
`BaseOperator` and has special handling for serialization.

So rename it to `task_params` or anything else, and you should be good.



On Thu, Dec 9, 2021 at 9:44 AM Anthony Joyce <[email protected]>
wrote:

> Hi Daniel-
>
> After some trial and error, I was able to isolate the issue. It has to do
> with my customer operator. See code below:
>
> from airflow.providers.mysql.hooks.mysql import MySqlHook
> from airflow.hooks.postgres_hook import PostgresHook
> from airflow.models import BaseOperator
> from airflow.utils.decorators import apply_defaults
> from contextlib import closing
> from typing import Dict, Optional, Union
>
> class *MySqlToPostgresOperator*(BaseOperator):
>     """Selects data from a MySQL database and inserts that data into a
>     PostgreSQL database. Cursors are used to minimize memory usage for
> large
>     queries.
>     """
>
>     template_fields = ("sql", "postgres_table", "params")
>     template_ext = (".sql",)
>     ui_color = "#944dff"  # cool purple
>
>     @*apply_defaults*
>     def *__init__*(
>         self,
>         sql: *str*,
>         mysql_conn_id: *str* = "mysql_default",
>         postgres_table: *str* = "",
>         postgres_conn_id: *str* = "postgres_default",
>         params: Optional[Dict[*str*, Union[*str*, *int*]]] = *None*,
>         rows_chunk: *int* = 5000,
>         *args,
>         **kwargs,
>     ):
>         *super*().__init__(*args, **kwargs)
>         if params is *None*:
>             params = {}
>         self.sql = sql
>         self.mysql_conn_id = mysql_conn_id
>         self.postgres_table = postgres_table
>         self.postgres_conn_id = postgres_conn_id
>         self.params = params
>         self.rows_chunk = rows_chunk
>
>     def *execute*(self, context):
>         """Establish connections to both MySQL & PostgreSQL databases,
> open
>         cursor and begin processing query, loading chunks of rows into
>         PostgreSQL. Repeat loading chunks until all rows processed for
> query.
>         """
>         source = MySqlHook(mysql_conn_id=self.mysql_conn_id)
>         target = PostgresHook(postgres_conn_id=self.postgres_conn_id)
>         with closing(source.get_conn()) as conn:
>             with closing(conn.cursor()) as cursor:
>                 cursor.execute(self.sql, self.params)
>                 target_fields = [x[0] for x in cursor.description]
>                 row_count = 0
>                 rows = cursor.fetchmany(self.rows_chunk)
>                 while *len*(rows) > 0:
>                     row_count += *len*(rows)
>                     target.insert_rows(
>                         self.postgres_table,
>                         rows,
>                         target_fields=target_fields,
>                         commit_every=self.rows_chunk,
>                     )
>                     rows = cursor.fetchmany(self.rows_chunk)
>                 self.log.info(
>                     f"{row_count} row(s) inserted into
> {self.postgres_table}."
>                 )
>
>
> Thanks,
>
> Anthony
>
>
> On Dec 9, 2021, at 11:52 AM, Daniel Standish <[email protected]> wrote:
>
> Can you provide a dag (as simplified as possible) which we can use to
> reproduce this error?
>
> On Thu, Dec 9, 2021 at 8:45 AM Anthony Joyce <
> [email protected]> wrote:
>
>> Hello fellow users-
>>
>> I have encountered an error which seems to be related to serialization:
>>
>> Broken DAG: [/home/etl/airflow/dags/airflow_platypus_etl_dag.py]
>> Traceback (most recent call last): File
>> "/home/etl/anaconda3/lib/python3.8/site-packages/airflow/serialization/serialized_objects.py",
>> line 574, in serialize_operator serialize_op['params'] =
>> cls._serialize_params_dict(op.params) File
>> "/home/etl/anaconda3/lib/python3.8/site-packages/airflow/serialization/serialized_objects.py",
>> line 447, in _serialize_params_dict if
>> f'{v.__module__}.{v.__class__.__name__}' == 'airflow.models.param.Param':
>> AttributeError: 'str' object has no attribute '__module__' During handling
>> of the above exception, another exception occurred: Traceback (most recent
>> call last): File
>> "/home/etl/anaconda3/lib/python3.8/site-packages/airflow/serialization/serialized_objects.py",
>> line 935, in to_dict json_dict = {"__version": cls.SERIALIZER_VERSION,
>> "dag": cls.serialize_dag(var)} File
>> "/home/etl/anaconda3/lib/python3.8/site-packages/airflow/serialization/serialized_objects.py",
>> line 847, in serialize_dag raise SerializationError(f'Failed to serialize
>> DAG {dag.dag_id!r}: {e}') airflow.exceptions.SerializationError: Failed to
>> serialize DAG 'Platypus_ETL': 'str' object has no attribute ‘__module__'
>>
>>
>> I have spent some time trying to figure out what is going on but to no
>> avail. Anyone have any insight on an error like this? I am on Airflow
>> release 2.2.2 and I am using the default packages constraints.
>>
>> Thanks all,
>>
>> Anthony
>>
>>
>

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