Drano should not ever be used in a dishwasher as the Drano can ruin the dishwasher.
When a dishwasher is clogged it's usually because the drain screen is clogged and you can usually remove the dishwasher drain screen with your hand or a screwdriver.
Then clean the food debris or calcium out of the dishwasher drain.
If the dishwasher drain pipe is clogged then you can take the drain line loose and then snake the drain or pour the Drano directly into the drain pipe that leads to your sink or sewer line.
You can use CLR in your dishwasher though to help remove any calcium deposits but don't use Drano in the dishwasher as it can damage the dishwasher.
Drano should also never be used in the toilet either as it can damage the Porcelain too.