Net.Data Reference Guide

Hidden Variables

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Hidden variables let you reference variables while hiding the actual variable name in your HTML source. It is easy to use hidden variables:

1. Define a variable for each string you want to hide.

2. In the HTML block where the variables are referenced, use double dollar signs instead of a single dollar sign to reference the variables. For example, $$(X) instead of $(X).

Example 1:

%HTML(INPUT) {
<FORM ...>
<P>Select fields to view:
<SELECT NAME="Field">
<OPTION VALUE="$$(name)"> Name
<OPTION VALUE="$$(addr)"> Address
</FORM>
%}
 
%DEFINE{
name="customer.name"
addr="customer.address"
%}
 
%FUNCTION(DTW_SQL) mySelect() {
  SELECT $(Field) FROM customer
%}

When the HTML form is displayed on a Web browser, $$(name) and $$(addr) are replaced with $(name) and $(addr) respectively, so the actual table and column names never appear on the HTML form and there is no way to tell that the true variable names are hidden. When the customer submits the form, the HTML(REPORT) block is called. When @mySelect() calls the FUNCTION block, $(Field) is substituted in the SQL statement with customer.name or customer.addr in the SQL query