I my last two posts I introduced QSDA Pro and the flag workflow. In this post I’m going to show how you can use QSDA Pro to quickly uncover quality issues in your Qlik Sense App.
QSDA groups flags by category, and the “Quality” category is where I usually begin my app review. Quality flags are used to indicate where something appears to be seriously broken such as:
- An expression syntax error.
- A reference to a Master Measure that no longer exists in the library.
- A missing extension.
- A bookmarked field that is no longer exists in the data model.
These are the kinds of things you want to discover before your users do!
It’s relatively easy to create new errors in an existing Qlik app. Qlik does not warn or block you from deleting a resource like a Field or Measure that is in use.
A properly done field rename may update names in expressions. But it will not update variables or bookmarks. And I’ve seen plenty of field renames go wrong and break expressions as well.
It can be difficult to detect all app errors by visually checking your app. The broken piece may be a color expression or a calculation condition that isn’t readily visible.
So yes, easy to break, sometimes hard to detect and heros find problems before their users do. Enter QSDA Pro.
In QSDA menu, Help -> Flag List will display a list of all potential flags in the installed version. Here’s the current list for Quality (The “{}” bits are values that will get filled in when the flag is created.)
Some of these are fairly straightforward, some a bit more subtle.
Why would you have a missing Master Dimension or Measure? A fairly common scenario is not understanding that Master Items are referenced by internal Id, not by Name. So you create something called “Sales” and use it in several charts. Later you are doing some exploration and create something called “Sales2” which you like better. So you think if you delete “Sales” and rename “Sales2” to “Sales” everything will be using the new “Sales”. Wrong.
Because the master item is now gone, I can’t tell you what used to be in this master item. You will have to rely on an app backup. Or…if you have a previous QSDA Analysis for this app you can look up the master item definition there!
All Expressions and Dimensions are validated using the Qlik syntax checker. A typical error might be a bad fieldname (perhaps because the field was removed from the model).
Flag Details will give us a detailed error message, location of this expression (Master Library) and importantly the Use Count. This use count is zero so we know deleting the measure is a viable option.
QSDA uses the Qlik syntax checker so the test is only as good as what I get from Qlik. There are some limitations, for example when column labels are used in an expression. You’ll note that the Qlik expression editor flags this as invalid so QSDA will pass this message on.
The “Parse Error” flag is raised when Qlik Syntax says the expression is ok but QSDA finds the expression does not conform to expected syntax rules. This could be a problem with the QSDA parser (a work in progress) or it could be Qlik tolerating something unusual. For example, do you think this is a valid expression?
sum({<Sales={">10 between < 90"}>}Sales)
The Qlik syntax checker will declare it valid. And it will return an official looking result — which may or may not be correct. But what is that “between” keyword? (if you’re curious why “>10 के बीच < 90” also seems to work, see https://masterssummit.com/something-to-get-confused-about/).
Nervous about refactoring or changing your apps? Can you relate to “Change Paralysis” or Fear Driven Development (FDD)? We all need a tool like QSDA Pro to proactively plan changes as well as audit after the fact for unintended errors.
Download QSDA Pro now and analyze some of your own apps. QSDA Pro is free to use during the beta period.
You can analyze published and unpublished apps, so go ahead and take a look at some of those production apps. Let me know in the comments if you find something interesting!
-Rob
