<Variable>

<Variable> stores a value under a name so other tags on the form — <SelectCommand> parameters, <Email> bodies, action tags like <AddToRoles>, and so on — can read it via a [[FieldName]] token.

It's most useful when the same token-derived value (e.g. [[User:Id]], [[Url:state]]) is referenced in several places, or when an action tag needs a value that isn't tied to a visible form control. Unlike a hidden <TextBox>, <Variable> doesn't render as an HTML element at all — there's no input on the page, no postback round-trip, and no risk of a user tampering with the value.

Example

In the example below, <Variable Name="uid"> captures the current user's ID once. The <AddToRoles> action then references it as [[uid]]. Without the variable, the same [[User:Id]] token would have to be repeated everywhere.

<AddForm>
  <Variable Name="uid" Value="[[User:Id]]" />
  <SubmitCommand CommandText="INSERT INTO Users(FirstName, LastName)
                              VALUES(@FirstName, @LastName)" />
  <AddToRoles RoleNames="Editors" UserId="[[uid]]" />

  <Label For="txtFirstName" Text="First Name" />
  <TextBox Id="txtFirstName" DataField="FirstName" DataType="String" /><br />

  <Label For="txtLastName" Text="Last Name" />
  <TextBox Id="txtLastName" DataField="LastName" DataType="String" /><br />

  <AddButton Text="Add" /> <CancelButton Text="Cancel" />
</AddForm>

Properties

Property	Values	Default	Description
Name *	string		The name other tags use to reference this value, as a field token ([[Name]])
Value	string | token		The value to store. Function tokens are evaluated when the form loads
DataType	database type	String	The type used when the variable is bound to a SQL parameter

* Required property

Property Details

• Name: The token name. Choose something distinct from your form's DataField names to avoid collisions. Other tags reference the variable via [[Name]].

• Value: The value to store. Hard-coded strings, function tokens ([[User:Id]], [[Url:state]], [[Portal:Id]], etc.), and concatenations are all valid.

Variable vs. hidden TextBox

A hidden <TextBox Visible="False"> accomplishes something similar, but it round-trips through the page (it lives in viewstate, can be tampered with via the browser's developer tools, and adds an HTML element). <Variable> is the better fit when you just need a name for a value the form already knows.