Cities with no troops guarded by Traps/Turrets

Say someone attacks a city that has a number of traps of turrets, but no troops. Does the attacking player still have to push their way through the traps or turrets? Also If the turrets kill some of the attacking troops, will the defending player gain prestige from this, as he losing no troops but has killed a few enemy troops?

I know many players don't attack if there is no troops, but maybe somebody tries to farm a city rich in resource.

Ok so as an attacker to win a battle there must be no enemy troops, traps or turrets left. PP can only be taken by the person who wins the battle (aka the person with something left at the end) of both sides have something left or both sides have nothing left the defender wins.

As long as you win the battle even if your enemy kills nearly all your troops you will lose 0 pp

If someone attacks your city and sees high level turrets, they can plow through em for your resources (assuming you had no troops out) or they can just wait 20 turns and the battle ends, your turrets stay there untouched and his army goes on it's merry way, now wary of your cities wall