SQLAlchemy ON DUPLICATE KEY UPDATE

Question

Is there an elegant way to do an INSERT ... ON DUPLICATE KEY UPDATE in SQLAlchemy? I mean something with a syntax similar to inserter.insert().execute(lis

Answer 1

Based on phsource's answer, and for the specific use-case of using MySQL and completely overriding the data for the same key without performing a DELETE statement, one can use the following @compiles decorated insert expression:

from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import Insert

@compiles(Insert)
def append_string(insert, compiler, **kw):
    s = compiler.visit_insert(insert, **kw)
    if insert.kwargs.get('on_duplicate_key_update'):
        fields = s[s.find("(") + 1:s.find(")")].replace(" ", "").split(",")
        generated_directive = ["{0}=VALUES({0})".format(field) for field in fields]
        return s + " ON DUPLICATE KEY UPDATE " + ",".join(generated_directive)
    return s