MvWHILE#
Loops through the code between and until the condition in EXPR is false. Optionally you can exit the loop using .
<MvWHILE EXPR = "{ expression } | variable name">
<MvWHILESTOP>
<MvWHILECONTINUE>
</MvWHILE>
Care must be taken to ensure an endless loop is not created. The Empresa engine will eventually time out, but the loop will consume server resources until that happens. The <MvWHILESTOP> command can be used to exit a loop at any time.
Attributes#
| Attribute | Description |
|---|---|
EXPR |
Required, returns a value interpreted as a conditional expression, typically involving a comparison, string, or logic operator. The expression must return a true for Miva Script to process the code that follows the <MvWHILE> tag. An <MvWHILE> tag must have a closing </MvWHILE> end tag. |
Examples#
<MvWHILE EXPR = "{ condition }">
Execute the code here repeatedly while this condition is true.
</MvWHILE>
In this example the code executes a fixed number of times.
<MvASSIGN name="g.counter" value="1">
<MvWHILE EXPR = "{ Counter LE 10 }">
Execute the code here 10 times.
<MvASSIGN name="g.counter" value="{ g.counter + 1}">
</MvWHILE>
Breaking out of a loop. Loops can be ended manually using <MvWHILESTOP>, for example when an error is detected, or to prevent an endless loop.
<MvWHILE EXPR = "{ 1 }">
Execute the code here endlessly.
<MvIF EXPR="{ g.counter GE 100 }">
<MvWHILESTOP>
</MvIF>
<MvASSIGN name="g.counter" value="{ g.counter + 1}">
</MvWHILE>
Often when processing data, the number of loops is often not known in advance so other conditions must be tested. In this example, l.fieldlist is a comma separated list of values and is output to the browser one line at a time.
<MvASSIGN NAME="l.posn" VALUE="{ 1 }">
<MvASSIGN NAME="l.item" VALUE="{ gettoken(l.fieldlist,',',l.posn) }">
<MvWHILE EXPR="{ l.item }">
<MvEVAL EXPR="{ l.posn $ '. ' $ l.item }"><br>
<MvASSIGN NAME="l.posn" VALUE="{ l.posn + 1 }">
<MvASSIGN NAME="l.item" VALUE="{ gettoken(l.fieldlist,',',l.posn) }">
</MvWHILE>