Getting element from an array where data may not exist

Question

I am trying loop over elements in an array

data = [];

data[3] = true;
data[4] = false;

for (i = 1; i <= data.len(); i++) {
    if(data[i])   {
        writeoutput("Kittens!")
    }
}

And I get an error

Not an option

My code is a simplification of larger process. The following is NOT an option

for (datum in data) {
    if(datum)   {
        writeoutput("Kittens!")
    }
}

Sev Roberts · Answer 1 · 2020-06-17T09:37:05.503

Unless I've missed the point then that's what arrayIsDefined() is for, eg:

<cfscript>
data = [];

data[2] = javaCast( "null", 0 );
data[3] = true;
data[4] = false;

for (i = 1; i <= data.len(); i++) {
    if(arrayIsDefined(data,i) && data[i])   {
        writeoutput("Kittens!");
    }
}
</cfscript>

This fiddle demonstrates the above and confirms that it also safely handles the presence of an explicitly set null element in the array: https://cffiddle.org/app/file?filepath=97b96317-8dcd-4620-a953-2c895191a8dc/67ccc09d-f4b5-4a2e-93d6-4cf3269a29d3/19c13ebe-1af4-4c72-9d7c-4cb82fa58f13.cfm

score 2 · Accepted Answer · answered Jun 17 '20 at 18:19

You could always channel The King...

<cfscript>
data = [];

data[3] = true;
data[4] = false;



for (i = 1; i <= data.len(); i++) {

    if( data[i]?:false )   {
        writeoutput("Kittens!");
    }
    else { writeoutput("nope"); }
}


</cfscript>

https://trycf.com/gist/d8664be620520252871e91796bef2f61/acf2016?theme=monokai

score 0 · Answer 3 · answered Jun 17 '20 at 11:16

Another approach is to use try/catch.

<cfscript>
data = [];

data[3] = true;
data[4] = false;
for (i = 1; i <= data.len(); i++) {
try {
    if(data[i])   {
        writeoutput("Kittens!" & i & "<br>")
    }
}
catch (any e) {
writeoutput("puppies " & i & "<br>");
}

}
</cfscript>

Getting element from an array where data may not exist

3 Answers3