Use the value of a field inside an administration action

Using Django
3 
class MyModelAdmin(admin.ModelAdmin):

readonly_fields = ('code', 'nom', 'prenom', 'sexe', 'datenaiss', 'lieunaiss', 'annee_bepc', 'centre_bepc', 'numtable',
               'datecreation', 'datecreation', 'datemodification', 'image_tag',)
#list_editable = ('env1', 'env2')
list_display = ('image_tag', 'code', 'nom', 'prenom', 'sexe', 'datenaiss', 'lieunaiss', 'annee_bepc', 'centre_bepc',
               'datecreation', 'env1', 'env2', 'valide_poste', 'param_secret' )


search_fields = ('nom', 'prenom', 'code', 'numtable', 'datenaiss', 'lieunaiss', 'numpi', 'numtel', 'env1', 'env2',)
list_filter = (
    ('annee_bepc', DropdownFilter),
    ('sexe', DropdownFilter),
    ('valide_poste'),
    ('valide_agence_id__agence', DropdownFilter),
)
#filter_horizontal = ['annee_bepc', 'sexe']
ordering = ('-code', 'datecreation', 'nom', 'prenom', 'datenaiss', 'lieunaiss', 'nompere', 'nommere', 'sexe',)
actions = ['auth_valide_poste', 'auth_imp_recu_poste', ]
actions_on_bottom = True

class Media:
    js = [
        '/admin/menu_filter_collapse.js',
    ]

def get_readonly_fields(self, request, obj=None):

    # Group Poste
    if request.user.groups.filter(name='poste').exists():
        readonly_fields = ('code', 'nom', 'prenom', 'sexe', 'datenaiss', 'lieunaiss', 'annee_bepc', 'centre_bepc',
                           'numtable', 'numtel', 'email', 'numpi',
               'datecreation', 'datecreation', 'datemodification', 'image_tag', 'photo_cand', 'nompere', 'nommere', 'valide_poste')
        return  readonly_fields

    # Group Superuser
    if request.user.is_superuser is True:
        readonly_fields = ('code', 'datecreation', 'image_tag', )
        return  readonly_fields

    return super().get_fieldsets(request, obj=obj)





def auth_imp_recu_poste(self, request, queryset):
    if not request.user.has_perm('concours.auth_valide_poste'):
        messages.error(request, 'Vous n\'êtes autorisé(e) à effectuer cette action')
    else:
        #k = 'be186847-9aaf-45db-a1bb-ae966979bf52'
        r = MyModel.objects.get(code__exact=code).param_secret
        k = r
        return HttpResponseRedirect(reverse('generatePdfAuth', args=[k]))

auth_imp_recu_poste.short_description = "Imprimer les reçu de paiement Poste-CI"

Here is my code (admin.py). I would like inside the ‘auth_imp_recu_poste’ administration action to have access to the ‘param_secret’ field to send it as a parameter to one of my views.