All these remedies will probably work however you need to look at why he's constipated in the first place otherwise it will be ongoing.
Once they are on solids they need to drink water on a daily basis and that is the preferred option to fruit juice which is high in sugar and not good for their teeth - they are much better off eating fruit.
Banana, white bread, farex... are just some things that can cause constipation, that and not enough water in his diet to help his body process the food. Look at what he's eating which is leading to the constipation then modify his diet, it might be that he can only eat a little of those foods but if he regularly drinks water this should assist.
You dont want to have to medicate him all the time so he can poo, it can be managed through diet (unless there's a structural problem like a blockage but that's rare).