Basic Debugging 101
You’re having trouble with a data flow, so h ow do you find what’s wrong? We’ll look at some basic debugging techniques.
Debug mode
Data Flow Designer (DFD) offers a debug mode that will help guide you to find what might be issues within a data flow. You can get into debug mode by either using hotkey <ctrl>-D, or right-click and choose Debug View.
Let’s say we have the following Data Flow. Something appears wrong because we see warning icons.
Now let’s turn on debug mode. The view changes to show more information.
The title bar of each component now has its unique name within the data flow. If you receive an error, you can expose and find the offending component.
Now let’s click on a component.
On the left you’ll see s list of input parameters. These are the input parameter names the component is expecting to receive. If any of the parameters are not supplied by an upstream and connected component, then you get,
- Warning icon
- Parameter names in red, appearing first, of those not supplied
It’s not always true that a warning icon means “problem”, but often it’s an indicator of a missing parameter, a missing line, a misconfigured telemetry map, and so on.
The right side of the Evaluator above is the symbol for Barrier, which we’ll cover in a more advanced entry.
Component Search (Find)
What if you have many components and need to find one? You may have many of one component type and you receive an error about “ComputationSet14“, but your data flow is very large. You can choose from,
- Right click, select Find…
- <ctrl>-F
Then just start typing the name of the component and auto-fill will help you.
Click Find (or just hit <enter>) and the component will be selected, including scrolling if the component is off-screen.
Summary
In this article, we’ve taken a look at some of the tools useful for debugging. Next we’ll take a look at viewing data moving through the data flow.