# documentation:2.0:exportedvars
Keywords: documentation,2.0,exportedvars

# Exported variables

## Presentation

Exported variables are the variables available to write rules and headers. They are extracted from the users database by the users module.

To create a variable, you've just to map a user attributes in LL::NG using `Variables` » `Exported variables`. For each variable, The first field is the name which will be used in rules, macros or headers and the second field is the name of the user database field.

Examples for LDAP:

Variable name | LDAP attribute
--- | ---
uid | uid
number | employeeNumber
name | sn

You can define exported variables for each module in the module configuration itself. Variables defined in the main `Exported variables` will be used for each backend. Variables defined in the exported variables node of the module will be used only for that module.

You can define environment variables in `Exported variables`, this allows one to populate user session with some environment values. Environment variables will not be queried in users database.

## Extend variables using macros and groups

Macros and groups are calculated during authentication process by the portal:

- macros are used to extend (or rewrite) exported variables. A macro is stored as attributes: it can contain boolean results or any string
- macros can also be used to import environment variables (these variables are in CGI format). Example: `$ENV{HTTP_COOKIE}`
- groups are stored as space-separated strings in the special attribute “groups”: it contains the names of groups whose rules were returned true for the current user
- You can also get groups in `$hGroups` which is a Hash Reference of this form:

    $hGroups = {
              'group3' => {
                            'description' => [
                                               'Service 3',
                                               'Service 3 TEST'
                                             ],
                            'cn' => [
                                      'group3'
                                    ],
                            'name' => 'group3'
                          },
              'admin' => {
                           'name' => 'admin'
                         }
            }

Example for macros:

    # boolean macro
    isAdmin -> $uid eq 'foo' or $uid eq 'bar'
    # other macro
    displayName -> $givenName." ".$surName

    # Use a boolean macro in a rule
    ^/admin -> $isAdmin
    # Use a string macro in a HTTP header
    Display-Name -> $displayName

Example for groups:

    # group
    admin -> $uid eq 'foo' or $uid eq 'bar'

    # Use a group in a rule
    ^/admin -> $groups =~ /\badmin\b/

    # Or with hGroups
    ^/admin -> defined $hGroups->{'admin'}

Groups are computed after macros, so a group rule may involve a macro value.
Macros and groups are computed in alphanumeric order, that is, in the order they are displayed in the manager. For example, macro “macro1” will be computed before macro “macro2”: so, expression of macro2 may involve value of macro1. As same for groups: a group rule may involve another, previously computed group.