So you've built out your app and everything is working great, provided the user enters in all the information requested by your well-thought-out and organized user interface. How do you protect yourself from a flood of emails due to user error?

With the addition of a simple-to-configure tool, you can easily add checks and custom error messages if things are not entered correctly.

The Error Message Tool (Interface Toolset) is simple to configure and can provide the assurance you need to make sure that the information requested by your Analytic App is being entered correctly.

The Error Message tool connects to questions and allows you to build out a custom expression to ensure the data entered is what you're looking for. One of the most common uses is simply to make sure something was entered. To do this, connect your Error message tool to any question in your app and fill out the configuration as shown below:

When I run my app and leave the answer to that question blank, my error appears:

You can also use a single Error Message tool for multiple questions. Instead of building a separate message for each user's required input, you can connect additional questions into a single Error and return an error if any of them are left unanswered:

You'll notice the questions are represented by [#1] and [#2] in the expression. This corresponds to the numbered connection line feeding into the Error Message tool. A best practice is to rename those lines so that you know which connection applies to each question. The process of renaming is simple. With any tool configuration window open, click on the connection line you wish to rename and enter the name you want to change it to. You'll see the change on the workflow canvas itself, as well as within the Error Message tool:

Now if a user leaves either one of the questions blank, an error will appear stating that he/she must answer all questions.