Importing a MySQL database with a Python script fails when the same command works on the command line, what gives?

Question

I'm running a MySQL server in docker container and am trying to import a .sql file in a Python script (Flask app). This is my code:

os.system("docker exec -i %s_db_1 mysql -u<username> -p<password> <db name> < %s" % (name, db_file))

It returns this error in the terminal the Flask app is running in:

ERROR 1064 (42000) at line 1835: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

If I run this command from the command line, it works. I can't really figure out how using os.system in this instance is meaningfully different. I've also tried subprocess.call and it produces the same error.

Answer 1

Your MySQL request is not well formatted, are you sure it works on command line ?

You should try:

os.system("docker exec -i {0}_db_1 mysql -u {1} -p {2} {3}".format(db_file, username, password, db_name))

Answer 2

I am using NamedTemporaryFile and it turns out that the file wasn't finished writing to disk when I was trying to use it. If I call db_file.flush() right before os.system everything works.