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Erik_27939's avatar
Erik_27939
Icon for Nimbostratus rankNimbostratus
Aug 20, 2014
Solved

How do you handle a null variable in an irule?

I am using the below logic: if { [string length $sort_dest_pool] > 0 } { set dest_pool [string trimleft $sort_dest_pool "$loc"] } else { set dest_pool $orig_pool } ...
application delivery
devops
iRules
LTM
  • nitass_89166's avatar
    nitass_89166
    Aug 21, 2014

    can you try to remove $?

    e.g.

    % info exists t
0
% set t 1
1
% info exists t
1
hooleylist's avatar
hooleylist
Icon for Cirrostratus rankCirrostratus
Aug 22, 2014

Yep, you can use [info exists varname] to check if a variable is defined. Or you could set it to a null value by default and then check it later to see if it's not null:

when HTTP_REQUEST {

    if {$some_condition == 1}{
        set sort_dest_pool "my_pool"
    } else {
        set sort_dest_pool ""
    }

     later...

    if {$sort_dest_pool eq ""}{
         Take some default action
    } else {
        pool $sort_dest_pool
    }
}

Aaron