Hidden Fields and Calculations

Arclab® Web Form Builder

Hidden Fields

Hidden fields work essentially the same as input fields, the only difference being that no direct input is required for the hidden fields. They are mainly used in connection with calculations and logic elements. Hidden fields are transmitted exactly like input fields and can be used in email and database.


Add a new element and go to "Special Elements" > "Hidden Fields":


Add a Hidden Field

Texts and Numerical Values

Go to "Special Elements" > "Hidden Fields" and add a "Variable (Hidden Field)" to your form.
The position in the form does not matter.


Variable (Hidden Field)


Each hidden field has a unique field name through which the content can be accessed. Field names are displayed in curly brackets within the program, e.g. {Name}.

A "Variable (Hidden Field)" can contain text as well as a numeric value. When you create a new variable, the value is empty.
You can also preassign the variable with a numerical value or text in "Initial Content". You can simply enter text (without quotation marks) or a numeric value.

Hidden fields are displayed in "Design Mode" (see below), but they are not visible in "Preview Mode" and in the created form.


Edit Hidden Field


In the example above, a "Hidden Field" with the name "{MyField}" and the numerical value "0.19" was created.

Random Values

If you need a random value, you can also use the "Variable" or "Random Value" (Hidden Field) form element.


To do this, simply select the random value you want:


Random Value


In the example above, the "{MyRandomValue}" field is to be preset with a random integer between 5 and 25.


If you need a unique random ID, you can use the form element "UUID v4 (RFC 4211)".
This has the advantage that the probability of duplicate values is very unlikely and is therefore particularly suitable for order numbers or the like.

Combine Fields

With the form element "Special Elements" > "Hidden Fields" > "Combine Fields", a new hidden field is generated which contains a combination or sequence of fields and / or texts. This element is very versatile and can be used with texts as well as numeric values. In this case, however, there is no addition but a sequence of values.



In the following example, a new hidden field with the name "{Name}" is to be created from the two input fields "{First_Name}" and "{Last_Name}".


Combine Fields


If the user enters e.g. "John" as first name and "Doe" as last name the result {Name} would be "Doe, John".

Date and Time

The form element "Special Elements"> "Hidden Fields"> "Date and Time" is very versatile and can be assigned a fixed date as well as used to calculate the date. You can choose the date or time format, depending on whether you need the date, time or both:


Date Time Format



Sample: Current Date

In the following example a new field with the name "{MyCurrentDateField}" is to be created, which contains the current date (and time).


Current Date



Sample: Calculate Date and Time

In the following example, a new field with the name "{Departure}" is to be created, which should be the date 7 days after the arrival selected by the user in a date picker (calendar).


Calculate Date


The input field {Arrival} is used here as the basis for calculating the hidden field {Departure}.
Of course, you can also use another hidden field of the "Date and Time" type as the basis for the calculation.


Various elements for calculation are available in the program. You can find these under "Special Elements"> "Calculations":




  • "Mathematical Expression" is used to calculate numerical values. Both hidden fields and input fields can be used in the formula.
    The result of the calculation is a numerical value which is saved in a new hidden field.

  • "Calculate Date and Time" is used to add or subtract a timespan from a base date.
    The result is a date which is saved in a new hidden field.

  • "Timespan" is used to calculate a timespan, i.e. the period between two date fields.
    The result is a numerical value which is saved in a new hidden field.

  • "Age Calculation" is used to calculate the age at the current time.
    The result is a numerical value which is saved in a new hidden field.


The calculations are automatically updated as soon as a value (field) is changed in the form.