UDF Output Logger

The Pytest SLC Plugin helps accessing and analyzing the output of UDFs (User Defined Functions), see docs.exasol.com.

Since UDFs cannot print to your console, you can only retrieve messages from UDFs via network transfer, e.g. using sockets. PYTSLC class UdfOutputLogger can redirect output from UDFs to your local console or wait for specific messages.

The class can be used as a context with the following arguments:

Argument	Default value and alternatives
query (mandatory)	pyexasol_query_func(pyexasol_connection)
host (optional)	Default: localhost as seen from a UDF, even when dockerd runs in a virtual machine
print_func (optional)	Default: print, alternatively use LogPipe

The following minimal example uses pyexasol_query_func() and prints the UDF output to stdout.

Minimal Example

from exasol.pytest_slc import udf_debug as ud

query = ud.pyexasol_query_func(pyexasol_connection)
with ud.UdfOutputLogger(query):
    query("SELECT print_something() FROM DUAL")

Here is an example, using a LogPipe and waiting for a specific message.

Example using LogPipe

from exasol.pytest_slc import udf_debug as ud

query = ud.pyexasol_query_func(pyexasol_connection)
pipe = ud.LogPipe()
with ud.UdfOutputLogger(query, print_func=pipe.input):
    query("SELECT print_something() FROM DUAL")
    ud.wait_for_messages(pipe.output, "Hello from UDF")

Function wait_for_messages() has the following arguments:

Argument	Default value and alternatives
read_line (mandatory)	Function to retrieve new messages, use LogPipe.output for example.
*expected_messages (mandatory)	One or multiple messages of type str to wait for.
timeout (optional)	Default: 10 seconds.