How can i fix my gate so my dogs wont escape anymore...?

Okay well my sisters are legit ditz sometimes and dont shut the gate hard enough for it to lock shut. The gate itself is old and my mom was planning on buying a new one. So does anyone have any ideas/recommendations on a new gate that is good for dogs on a patio? I have 3 dogs one is a poodle/beshon the other two are yorkie chiuawas and are all gorgeous dogs that i love and i want to keep them safe. So please give me some advice thanks!