XForms has a variety of controls available that let you dictate what fields on a form are required or optional, what values are allowed to be entered in specific fields, and what the field display formats should look like. These controls can be split into validation controls and format controls, as described below.
Available validation controls
- Required (field cannot be left blank)
- Read-only (cannot enter any values into the field)
- Default value (specific value is pre-loaded into field)
- Minimum value (applies only to numeric and date fields)
- Maximum value (applies only to numeric and date fields)
- No Default Date (loads blank in date field)
- Show Time Zone (displays 3-character time zone in date field)
Available format controls
Date |
Time |
Number |
Text |
| US Standard (06/15/2021) | 12-hour (08:35 PM) | # of decimals (0 for integer) | UPPERCASE |
| Canadian Standard (15/06/2021) | 24-hour (20:35) | Minimum Value | lowercase |
| ISO Standard (2021-06-15) | Read-only (on-off switch) | Maximum Value | Title Case |
| Month Name (15-Jun-2021) | Required (on-off switch) | Default Value | Maximum Length (# of characters) |
| Required (on-off switch) | No Default Time (on-off switch) | Required (on-off switch) | Default text |
| Read-only | Show Time Zone (on-off switch) | Read-only | Read-only |
| Read-only |
When to use valid value ranges
You can set up a range of values that can be entered into certain fields of your form. In XForms, these are available for number and date fields, where you can enter a minimum value and maximum value.
A classic example of a number field using a valid value range is pH, which is a measurement used to specify the acidity of an aqueous solution. The pH scale goes from 0 to 14. You can’t have a pH below zero or above 14. So in XForms, you would create a number field to capture pH, and set the minimum value to 0 and the maximum value to 14. Then when a field user enters a pH value into that field, they can’t enter a number like 77 (maybe they meant to enter 7.7 but forgot to tap on the period).
An example of a date field with a minimum and maximum value could be a birthdate field. you could set a minimum date of January 1, 1930 and a maximum date of January 1, 2022. The thinking there is that no one using the system is going to be a baby or toddler. I personally don’t find this optional setting important, but there are certain use cases where it might be.
How to use “No Default Date” or “No Default Time” validation controls
A typical use case for using the “No Default Date” or “No Default Time” control is when you have an end date or end time on a form and want to force a user to enter the end date or time. In this use case, you would set that field to required and to No default. Then when the form first loads, no value is pre-loaded into the field, and the user can’t submit the form until they enter a value. Here’s what that looks like in the Designer:
How to use the text field format controls
Here’s an example illustrating the use of format controls in a text field. In the example below, the well_id field is set to display text in uppercase, with a maximum text string length of 15 characters, and a default value of MW-. So when the user loads the form, this field will preload with “MW-” and anything the user types into that field will be converted to UPPERCASE. The field will also truncate anything entered past 15 characters.
While not fully comprehensive, the currently available validation and formatting controls in XForms are simple and not overly complex, and should provide enough options for most use cases. Our intent is to add additional formatting and validation controls over time as needed by our customers, but only in ways that are simple to understand and implement.
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