structFilter

Used to filter the key-value pairs in a structure.

structFilter(struct,function(key, value [,struct]){} [, parallel] [, maxThreads]) → returns struct

Member Function Syntax

someStruct.filter(function(key, value [,struct]){} [, parallel] [, maxThreads])

Argument Reference

struct struct
Required

Name of the structure to filter

callback boolean
Required

Closure or a function reference that will be called for each of the iteration. Returns true if the key-value pair in the structure should be included in the filtered struct. Support for passing the original struct to the closure function added in CF11 Update 5.

Callback parameters:

key* string : The key for the current iteration
value* any : The value for the current iteration
struct* struct : A reference of the original struct

parallel boolean
Default: `false`

Lucee 4.5+ true if the items can be executed in parallel

Values:

true
false

maxThreads numeric
Default: `20`

Lucee 4.5+ the maximum number of threads to use when parallel = true

Links more information about structFilter

Map, Reduce and other Higher Order Functions - A Primer for map, reduce, filter, and Higher Order Functions in general.
ColdFusion 11: .map() and .reduce() - A look at the new .map() and .reduce() methods that each of array, struct and lists all have

Examples
Sample code invoking the structFilter function

Example using a simple numeric comparison

Take a struct of items with their rating and use structFilter to return ones of a rating 3 and higher.

fruitRatings = {apple=4,banana=1,orange=5,mango=2,kiwi=3};

favoriteFruits = structFilter(fruitRatings, function(key, value){
     return value >= 3;
});
writedump(favoriteFruits);

Expected Result: {apple=4,orange=5,kiwi=3}

Example using a member function

This is the same example, but using a member function on the struct instead of a standalone function.

fruitRatings = {apple=4,banana=1,orange=5,mango=2,kiwi=3};

favoriteFruits = fruitRatings.filter(function(key, value){
     return value >= 3;
});
writedump(favoriteFruits);

Expected Result: {apple=4,orange=5,kiwi=3}

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