For a chain link:
You could drive a piece of 1/2" electrical conduit in the ground about a foot to 18" and use a 2' long piece of aluminum rod as a holder on each side. The rod would stand about 6 to 12 inches high and catch the fence near the bottom. Both are in Home Depot or Lowes.

For a wood or vinyl:
The fencing section in Home Depot and Lowes will have what you need to attach to the fence. Again, put conduit in the ground to hold the rod attached to the fence.

Scott

It's a black aluminum Jerrith fence. Would something similar to what you explained still work?

I am assuming you're not doing the fence yourself. The installer should have a similar method for holding the gates open available. Use my description for the wood/vinyl fence as a guide. The installer may have a different solution too.

Scott