[Cartoweb-users] How to identify start node and end node in shortest_path_astar when the user click 2 points on the map?

[Nguyen Thi Van An]

Hi everybody,

I'm  doing a project which needs to find a shortest path between two 
user's clicked points. I already  install successfully  pgRouting.

I use this function:
SELECT * from shortest_path_astar('SELECT gid as id, source, target, 
length as cost, x1, y1, x2, y2 FROM roads', 3, 7, false, false);

But the problem is that I can't identify exactly the start node and end 
node to find path. I already have the start point and end point of the 
user. But they don't select correctly the points on my roads. So I can't 
draw the path correctly on the map (The path begins with their start 
clicked point and ends with their end clicked point)

Anybody has experiences with this? Please help me!

Thanks so much.