How to determine whether page has any children

[marcin]

It's my method, probably Ryan will show a better one.

if($page->child() instanceof NullPage) {
// doesn't have
}
else {
// has
}

[ryan]

Hi Marcin,

The method you posted is one I hadn't thought of before, but it would certainly work just as well as any other. Another variation on it would be:

if($page->child()->id) {
   // has children 
} else {
   // does not have children
}

Here's the way that I usually do it. This is also what ProcessWire does before it executes the child() or children() methods, to decide whether a query should be executed:

if($page->numChildren) {
   // has children
} else {
   // doesn't have children
}