hello I'm trying to create a block that only lets water through but no luck i tried copying the air code but nope that didn't do it.

any suggestions?

This is really hard to achieve since your block would be replaced by it. And when the water decays your block will be gone too.

Unless you can live with that, there is no easy method. You would have to set up several different listeners which will place your block again after the water has decayed. The easier part would be giving water the ability to replace your block, which I don't know how it's done.

I think your best bet would be to copy/implement the code that handles fluid flowing/spreading,  then listen for block updates around your block.  If it detects water above or next to it,  replace any air blocks beside or below it with flowing water rendered at a height relative to the source (initially triggered) side . When the source side is air again or down to one height level,  no longer support the flowing water blocks around it.  Hope this makes sense,  trying to type this on my Phone before my brother needs a lift to cubs.

 

simplified psuedo code:

 

on (block update) {

  Check faces{

  If air,  set as output;

  If water,  set as input;

  Calc block's "water height"

  While (input)  support flowing water on outputs

  }

}

I tried that but it was buggy i should try and make my code better

You may be able to do something like when a water block is next to your block then it renders it as if the water is actually going though and make you block make its self act like a water block and continue the water, or another fluid that acts like water, on. If that made any sense. Sorry for the confusing answer, but that is the way I would do it. Good Luck