Cant check for "variable is not set" in Ternary Expressions

[sascha-egerer]

It is not possible to check if a variable is not set in a ternary expression.

{ myArray.invalidVariable ? 'yes' : 'no' } Will always return yes because myArray.invalidVariable is evaluated as a string as not variable is found with this name

{('{myArray.invalidVariable}' !== '') ? 'yes' : 'no'} does also not work as the parser does not recognize this syntax as a ternary expression but simply outputs the text.

[NamelessCoder]

Looks like we should change the default to NULL when variable does not exist. Regarding the more complex expression the TernaryExpressionNode and other ExpressionNodes only support strict variable references - and no nested expressions either.

[sascha-egerer]

I tried that already but had no time to dig further into this. Simply changing this behavior does not work as the function getTemplateVariableOrValueItself is used and this behavior is also required in some cases.

[NamelessCoder]

It would seem we should not use getTemplateVariableOrValueItself - instead we can use $renderingContext->getVariableProvider()->get('name'). The "variable or value itself" logic is intended for use in cases where you do need the hardcoded value, for example in MathExpressionNode where expression parts can be operators/operands/hardcoded numbers rather than merely variable references. The same is not true for TernaryExpressionNode which must explicitly only support template variable references.

[NamelessCoder]

On a side note: this expression node class could use a bit of cleanup to remove the 'true' and 'false' expression matches since they do not make sense in this context. And the expression needs a bit of love (wrong comments, too broad variable name matching) - https://github.com/TYPO3Fluid/Fluid/blob/master/src/Core/Parser/SyntaxTree/Expression/TernaryExpressionNode.php#L29