How can I check if a variable exists in Smarty?

Question

I'm using Smarty template engine.

I'm doing a simple login page. I set a variabile named error with a message if there are some problems, but IF NOT I get:

Notice: Undefined index: error

How could I check if this variable exists?

I only do:

{if $error}<h1>{$error}</h1>{/if}

thanks

The answers below do not take into account that a variable can be set to `null`. $error may exist and be null, in which case isset($error) returns false. — pwagner, Apr 25 '17 at 15:13

score 68 · Answer 1 · edited Nov 05 '21 at 14:20

68

There you go!

{if isset($error)}
    {* TODO something *}
{/if}

edited Nov 05 '21 at 14:20

Daniel Guerrero

answered Oct 13 '11 at 09:19

Wesley van Opdorp

score 57 · Accepted Answer · answered Oct 13 '11 at 09:20

57

isset() - smarty - php

isset($error)

answered Oct 13 '11 at 09:20

Wazy

score 3 · Answer 3 · answered Nov 06 '21 at 00:12

3

You can also use:

{if $error|default}<h1>{$error}</h1>{/if}

"|default" modifier check if variable exist and accept one param (default: empty string)

answered Nov 06 '21 at 00:12

r_a_f

score -3 · Answer 4 · answered Mar 17 '18 at 12:32

-3

This is short :) No warnings or errors.

{if $error}

answered Mar 17 '18 at 12:32

Dumindu Perera

2

As you could see in the question this produces a notice. I assume you have the errorlevel high enough that you don't see notices. – user2587656 Nov 07 '19 at 15:08
In PHP 8.1, the notice has become a warning: `PHP Warning: Attempt to read property "value" on null in [template]`. The compiled code would here be `tpl_vars['error']->value) {?>`, but tpl_vars['error'] wouldn't exist. – Dereckson Feb 05 '22 at 13:05

4 Answers4