Validation Assist
Introduction
The Validation Assist helps you build validation microflows in a more automated way using pre-built expressions. Validation rules are conditions that should be satisfied before an object is committed. There are different ways to set up data validations in Mendix. Building data validations in microflows is a manual and repetitive task and Validation Assist helps automate it.
The main features of the Validation Assist are the following:
- List of checks for all members which data type can be empty, for example, when a customer’s name is not filled in a form
- Prefilled dialog box with microflow and validation properties
- Ability to extract validations as a sub-microflow
- Ability to call an existing validation sub-microflow in a new validation microflow
- Auto-generation of the validation microflow
Validation Assist Overview
The Validation Assist is activated by default in the page elements where data validation might be needed. These elements are the following:
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a button with the Save changes on-click event
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a button with the Call microflow on-click event
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a button with no on-click event set for it
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the following input widgets:
- Text box
- Text area
- Drop-down
- Checkbox
- Radio button
- Date picker
- Reference selector
- Input reference set selector
To access the Validation Assist, right-click a button or an input widget listed above and select Generate validation microflow.
The Generate Validation Microflow dialog box is where you can configure all validations:
The dialog box consists of two sections:
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Microflow Properties, where the general properties of the validation microflow are configured. Properties contain the following:
- Microflow – microflow name
- Commit – defines whether changes should be committed to the database (only for buttons)
- Close Page – defines whether the page should be closed after clicking the button (only for buttons)
- On Event – defines when to trigger the validation check (only for input widgets), for more information on events, see On Click Events and Events Section
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Validations where validations for the microflow are configured. This section contains the following:
- List of checks for all members which data type can be empty. These checks are automatically configured with prefilled Caption, Rule, Error message (only for the buttons)
- New – adds new validations
- Edit– edits existing out-of-the-box empty check validations or other validations created by the user
- Delete – deletes the selected validation
- Move up and Move down – changes the order of validations in the list
- Duplicate – duplicates selected validation
- Extract submicroflow – extracts a list of validations and saves it as a new validation sub-microflow to reuse later
Using Validation Assist to Build Data Validations
You can configure a custom Save button with the help of the Validation Assist.
For example, you have an app for a hairdresser salon, where customers can view information on types of treatments, their prices, they have a customer profile and can schedule appointments. Your app has a validation microflow that checks the selected date and time: that the selected date is in the future, and that it is within the opening hours (from 8 AM till 5 PM and not on a weekend).
Your app also has a form where customers can schedule a hairdresser’s appointment. They need to fill in their name, select the type of a treatment (haircut, hair coloring, etc.) and pick the date and time. You would like the Save button to show an error message when any of the following conditions are not met:
- one or several fields in the form are not filled in
- the selected date and time is in the future and it is within the opening hours (from 8 AM till 5 PM and not on a weekend)
- the name of the customer is valid (the name has only alphabetical symbols)
To configure the Save button for the use case above, do the following:
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Open the page with the form called Appointment_NewEdit and right-click the Save button in it.
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In the drop-down list, select Generate validation microflow:
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In the Generate Validation Microflow dialog box, you can see that Microflow properties, for example, a microflow name, and validations were configured for you. Three expressions were added to validations: to check if the name, treatment type, and date and time fields are filled in:
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In your app, you already have a validation microflow that checks the selected date and time, you can call the microflow in the current validation. Do the following:
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Click New in the Generate Validation Microflow dialog box.
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In the Add Validation dialog box, set Type to Call a validation microflow.
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Select the existing validation microflow for Microflow and click OK.
The microflow is added to validations.
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You also would like to add one more validation that checks that the name of the customer is valid (the name has only alphabetical symbols). To add a validation, do the following:
- Click New in the Generate Validation Microflow dialog box.
- In the Add Validation dialog box, make sure that Type is set to Based on expression.
- For Member, select the Customer_Name attribute.
- In the Expression field, fill in $Appointment/Customer_Name.
- Click OK to save changes.
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You would like to save validations for the Customer_Name attribute (that the name is not empty and that it is alphabetical) as a sub-microflow to use them as a separate validation on a different page. Do the following:
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In the Generate Validation Microflow dialog box, select two validations for Customer_Name and click Extract submicroflow:
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In the Extract Validation Sub Microflow, click Extract Microflow.
The microflow is saved separately containing selected validations.
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In the Generate Validation Microflow dialog box, click Generate microflow.
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In the Validation Assist dialog box, click Open the microflow to view the configured microflow:
The created microflow is used for the Save button to validate all conditions. The sub-microflow can be used on a different page to validate the customer name.
You can now click Run Locally () in the Studio Pro top bar to run your app locally and test validations.