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setKeys
Last update:
May 18, 2026
Returns keys or elements of the set for listing or conversion.
Description
Returns the elements of the set in a form suitable for key-like access or listing.
Returns
Array or list.
Category
ColdFusion Set member methods
Function syntax
set.keys()
setKeys(set)Parameters
| Parameter | Description |
|---|---|
| set | Set (BIF form). |
See also
Example
The following example uses this API in
cfscript (syntax: set.keys()).
<cfscript>
s = setNew();
s.add("k1");
s.add("k2");
it = setKeys(s);
while (it.hasNext()) {
writeOutput(it.next() & " "); // k1 k2 (order not guaranteed for unordered set)
}
</cfscript>
Real-world example
Filter a struct to only keys that appear in an allowlist set (use toArray if keys() mirrors elements).
<cfscript>
/**
* Whitelist struct keys using a Set of allowed key names.
* Prefer toArray() if keys() is unavailable or setKeys does not return an iterator.
*/
function filterStructByAllowlist(required struct data, required any allowedKeySet) {
var out = {};
// Option A: array from set (portable)
var keyNames = allowedKeySet.toArray();
for (var k in keyNames) {
if (structKeyExists(data, k)) {
out[k] = data[k];
}
}
return out;
}
// Example: API may only return id and name
payload = {
"id": 100,
"name": "Ada",
"secret": "do-not-leak",
"internalOnly": true
};
allowed = setNew();
allowed.add("id");
allowed.add("name");
safe = filterStructByAllowlist(payload, allowed);
writeOutput(serializeJSON(safe)); // {"id":100,"name":"Ada"}
</cfscript>
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