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Ternary Operator ? x : y

This operator is a shortcut used to writing simplify the following syntax:

if (product.label != null && product.label.length() > 0) {
	return product.label
} else {
	return 'N/A'
}

You can rewrite this the above statement using the ternary operator:

return (product.label != null && product.label.length() > 0) ? product.label : 'N/A'

Or even And then simplify it even more since not-empty check in Groovy can be done like this:

return product.label ? product.label : 'N/A'

Elvis Operator ?:

This operator is a very useful shortcut to writing thisused to provide a default fallback value if certain variable is empty or null. If the expression in the middle of the ternary operator is identical to it's first expression, you should simplify the return statement from the previous example above using ?: operator:

return product.label ?: 'N/A' // Elvis operator

You can rewrite it like thisThis can be useful if you need for example to always return a date when target date is not set:

date = api.targetDate() ?: new Date() // if target date is null, we usereturn the current date

Or define a default value for a parameter if it is not set:

lookback = api.decimalUserEntry('Look-back period (default: 20)') ?: 20 // if the user doesn't specify the look-back period, it will default to 20

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Safe Navigation Operator ?.

When you check for a null reference every time you want to This operator provides a not-null check before accessing a value from object. Whenever you access object's attribute or method , you might be using something likeyou should check for a non-null reference like this:

if (date) {
	return date.format('yyyy-MM-dd')
} 
return null

Advanced Groovy allows you Instead of the case above, it is recommended to use the ternary operator instead:

return date ? date.format('yyyy-MM-dd') : null

But even better is to use the Safe safe navigation operator:

return date?.format('yyyy-MM-dd')

If the date is null, the whole expression will evaluate to return null. You can even chain the callsmultiple occurrences of safe navigation operator:

return product?.attribute21?.toBigDecimal()

Spread Operator *

Sometimes you may want to pass a collection of objects to a method which accepts a variable name of parameters only. Such as Filter.orImagine following api.find with many filters:

api.find('P', Filter.equal('attribute5'"attribute1", '"P'"), Filter.or(Filter.equal("attribute2", "Red"), Filter.equal('attribute5'"attribute2", 'M'"Green"),   Filter.equal("attribute2", "Blue")),Filter.equal('attribute5'"attribute3", 'U'),
]
 
// this will throw a compilation error as Filter.or doesn't accept a collection but a variable number of Filter arguments123))

It works fine, but is very difficult to read right? Therefore a following syntax is preferred:

def filter = Filter.and(
	Filter.equal("attribute1", "P"),
	Filter.or(
		Filter.equal("attribute2", "Red"),
		Filter.equal("attribute2", "Green"),
		Filter.equal("attribute2", "Blue"),
	),
	Filter.equal("attribute3", 123),
)

api.find('P', Filter.or(filtersfilter))

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It is now much easier to read what the filter is supposed to return and also distinguish the priorities between AND and OR, right?

Sometimes you may find following syntax that has identical meaning:

def filters = [
	Filter.equal("attribute1", "P"),
	Filter.or(
		Filter.equal('attribute5'"attribute2", 'P'"Red"),
		Filter.equal("attribute2", "Green"),
		Filter.equal('attribute5'"attribute2", 'M'"Blue"),
	),
 	Filter.equal('attribute5'"attribute3", 'U'123),
]
 
// notice the * char. This will unwrap each elementitem of the collection and pass it to the method as a separate parameter
api.find('P', *filters)

Common mistake is that you forget the * operator in the above case:

api.find('P', filters)

Groovy compiler will throw an compilation error since no version of api.find() does accept collection as argument but only a variable number of Filter objects:

No signature of method: net.pricefx.formulaengine.scripting.SandboxAPI.find() is applicable for argument types: (java.lang.String, java.util.ArrayList) values: [P, [`attribute1` = "P", (`attribute2` = "Red" or(*filters) `attribute2` = "Green" or `attribute2` = "Blue"), ...]]
Possible solutions: find(), find(java.lang.String, [Lcom.googlecode.genericdao.search.Filter;), find(java.lang.String, int, [Lcom.googlecode.genericdao.search.Filter;), find(groovy.lang.Closure), find(java.lang.String, int, java.lang.String, [Lcom.googlecode.genericdao.search.Filter;), uuid()

Spaceship Operator <=>

This operator delegates to the compareTo method of the left-side operand and passes it the right-side operand.  

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