How to explicitly declare charset=utf8 for Airflow connections

Question

This sequence:

from airflow.hooks.mysql_hook import MySqlHook
conn = MySqlHook(mysql_conn_id='conn_id')
engine = conn.get_sqlalchemy_engine()
df.to_sql('test_table', engine, if_exists='append', index=False)

produces the following:

UnicodeEncodeError: 'latin-1' codec can't encode character '\ufffd' in position 57: ordinal not in range(256)

This sequence works great:

from sqlalchemy import create_engine
engine = create_engine("mysql://{0}:{1}@{2}/capone?charset=utf8".format(user, pwd, host))
df.to_sql('test_table', engine, if_exists='append', index=False)

The key is in explicitly declaring the charset. I have attempted to do this in airflow as follows with {"charset": "utf8"}:

But this has not fixed the error. I've restarted my dev environment since making the changes and the admin panel lets me know that the edit was successful. How can I work with Airflow connections to my charsets as utf8?

Answer 1

I realised that this is a bug in Airflow and I have reported it here: https://issues.apache.org/jira/browse/AIRFLOW-4824

For now I have a workaround with the following code:

def get_uri(hook):
    conn = hook.get_connection(getattr(hook, hook.conn_name_attr))
    login = ''
    if conn.login:
        login = '{conn.login}:{conn.password}@'.format(conn=conn)
    host = conn.host
    if conn.port is not None:
        host += ':{port}'.format(port=conn.port)
    charset = ''
    if conn.extra_dejson.get('charset', False):
        chrs = conn.extra_dejson["charset"]
        if chrs.lower() == 'utf8' or chrs.lower() == 'utf-8':
            charset = '?charset=utf8'
    return '{conn.conn_type}://{login}{host}/{conn.schema}{charset}'.format(
        conn=conn, login=login, host=host, charset=charset)

And then use it as follows:

url = get_uri(sql_hook)
from sqlalchemy import create_engine
engine = create_engine(url)

The real solution will be to send a pull request to the project overriding get_uri in mysql_hook.py.

Answer 2

from sqlalchemy import create_engine
from airflow.hooks.mysql_hook import MySqlHook

conn = MySqlHook(mysql_conn_id='conn_id')
uri = conn.get_uri()
engine = create_engine(uri+'?charset=utf8')
df.to_sql('test_table', engine, if_exists='append', index=False)

I fixed the problem by the code above.