Both mv and ml will not be recognized, since you haven't defined them as variables.

The second argument of execute statement is a dictionary, and all the elements of your plain query "UPDATE client SET musicVol = :mv , messageVol = :ml" escaped with a colon are being searched for in this dictionary's keys. The execute method did not found a key 'mv' nor 'ml' in this dictionary, therefore an error is raised.

This is the correct version:

db.my_session.execute(
    "UPDATE client SET musicVol = :mv, messageVol = :ml",
    {'mv': music_volume, 'ml': message_volume}
)

You need to get the connection object, call execute() on it and pass query parameters as keyword arguments:

Copyfrom alembic import op
from sqlalchemy.sql import text

conn = op.get_bind()
conn.execute(
    text(
        """
            insert into field_tags 
            (id, field_id, code, description) 
            values 
            (1, 'zasz', :code , :description)
        """
    ), 
    **t
)

Also see: How to execute raw SQL in SQLAlchemy-flask app.

The documentation uses literal_binds to print a query q including parameters:

print(q.statement.compile(compile_kwargs={"literal_binds": True}))

the above approach has the caveats that it is only supported for basic types, such as ints and strings, and furthermore if a bindparam() without a pre-set value is used directly, it won’t be able to stringify that either.

The documentation also issues this warning:

Never use this technique with string content received from untrusted input, such as from web forms or other user-input applications. SQLAlchemy’s facilities to coerce Python values into direct SQL string values are not secure against untrusted input and do not validate the type of data being passed. Always use bound parameters when programmatically invoking non-DDL SQL statements against a relational database.

The question is a bit old already, but knowing myself, I will probably come back for this in future. This was the bit of code I was looking for:

import sqlalchemy
from sqlalchemy.sql.expression import bindparam
from sqlalchemy.types import String
from sqlalchemy.dialects.postgresql import ARRAY

DB_URI = '...'
engine = sqlalchemy.create_engine(DB_URI)

sql = text("SELECT * FROM some_table WHERE userid = :userid").bindparams(bindparam("userid", String))
res = engine.execute(sql, userid=12345)

# in particular this bit is useful when you have a list of ids
sql = text("SELECT * FROM some_table WHERE userids = :userids").bindparams(bindparam("userids", ARRAY(String)))
res = engine.execute(sql, userids=[12345, 12346, 12347])

if you truly want to talk to the driver and exec_driver_sql() is not good enough, get yourself a cursor and there you go.

that said, I dont see what the problem with text() is, colon signs get backslash escaped, and that's it. it's fully consistent on any driver:

conn.execute(
    text(f"CREATE VIEW some_name AS {definition.replace(':', '\:')}"),
)