Logging from a Mendix Java action

It is a common requirement to be able to log data from an application. Mendix has a good logging system built in, but how do we access this from a custom Java action?

The Mendix development team have already thought of this, and have provided a method called getLogger in the Core.

To use the logger from a Java action, we first need to add a couple of imports.

import com.mendix.core.Core;
import com.mendix.logging.ILogNode;

Now we need to provide access to the logger. We can do this by providing a static variable which we’ll call LOG. We use the getLogger method we mentioned earlier, passing in the name of the log node name we want to use. In this case, we’ll use “RobTest” as the log node name.

// BEGIN EXTRA CODE
public static ILogNode LOG = Core.getLogger("RobTest");
// END EXTRA CODE

Now, this is in place, we can access LOG from elsewhere in our Java action.

Let’s say our action wants to log when it starts and also wants to list all the microflows available within the App. We can change the log levels, so the start notification is at “info” level, and the microflows are at “debug” level. We can do this using the following.

public java.lang.Boolean executeAction() throws Exception
{
    // BEGIN USER CODE
    LOG.info("Running executeAction()");

    for (String mf : Core.getMicroflowNames()) {
        LOG.debug("Microflow: " + mf);
    }
    return true;
    // END USER CODE
}

When we execute the Java action, we see the following on the Mendix console.