Allow array (with default value) or null in Symfony 2.1 semantic configuration

Question

I need to define an array node with a given default value in a bundle's semantic configuration. This currently looks like:

$node->arrayNode('foo')
         ->prototype('scalar')->end()
         ->defaultValue(array('1', '2', '3'))
     ->end();

I want to give the user the option to override this array with null like:

my_bundle:
  foo: ~

I cannot use empty arrays ([] or array()) instead of null given that [] should have different semantics from null.

Is this possible or are there any non-ugly workarounds? Currently I just get an exception:

InvalidTypeException: Invalid type for path "my_bundle.foo". Expected array, but got NULL

You defined this as 'scalar' but default value is 'array', should it be array type? Scalar is integer, boolean, string — olegkhuss
– olegkhuss, Commented Oct 31, 2012 at 11:30

Aldo Stracquadanio · Accepted Answer · 2012-11-01 12:17:46Z

20

You could try something like:

$node->arrayNode('foo')
     ->beforeNormalization()
       ->ifTrue(function($v) { return $v === null; })
       ->then(function($v) { return array(); })
     ->end()
     ->prototype('scalar')->end()
     ->defaultValue(array('1', '2', '3'))
 ->end();

Or maybe the even simplier:

$node->arrayNode('foo')
     ->treatNullLike(array())
     ->prototype('scalar')->end()
     ->defaultValue(array('1', '2', '3'))
 ->end();

Otherwise you can use the variableNode rather than the arrayNode; this will give you more freedom but less validation/merging logic out of the box.

edited Nov 1, 2012 at 12:17

answered Oct 31, 2012 at 11:34

Aldo Stracquadanio

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3 Comments

Thomas Luzat Over a year ago

Thanks, but this looks as if I will get array() for null instead of null. I almost suspect that there is no other choice, though. It would probably be hard to express "override with null" vs. empty array in XML, too (not so much for Yaml).

Aldo Stracquadanio Over a year ago

Yes, that is what is going to happen, but I think that there is no easy escape from this: if you define an arrayNode you will eventually get an array after the configuration has been merged and normalized. You could consider having the foo node as a variableNode otherwise, which will give you more freedom but less validation/merging logic out of the box.

Thomas Luzat Over a year ago

If you added the variableNode part to the answer, I could accept it, given that I explicitly asked for a way which allows to consider [] different from null. arrayNode does not seem to be an option which fully does what I want.

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