How to conditionally add widgets to a list?
EDIT:
Since Dart 2.2, new syntaxes supports this natively:
Column( children: [ if (foo != null) Text(foo), Bar(), ],);This problem is currently debated on github here.
But for now, you can use dart sync* functions:
Row( children: toList(() sync* { if (foo == 42) { yield Text("foo"); } }),);where toList is:
typedef Iterable<T> IterableCallback<T>();List<T> toList<T>(IterableCallback<T> cb) { return List.unmodifiable(cb());}Not only it solves the conditional addition problem; it also allows for a "spread operator" thanks to yield*. Example:
List<Widget> foo;Row( children: toList(() sync* { yield Text("Hello World"); yield* foo; }),);
The new Dart syntax allows 'if' in lists, which leads to this simple solution:
Row( children: <Widget>[ if (foo == 42) Text("foo"), ],);
Here's a simpler version I use:
Row( children: [ Text("always included"), skipNulls([ icon, label, ]), ],);skipNulls<T>(List<T> items) { return items..removeWhere((item) => item == null);}