How to sort an array of structs in ColdFusion

Question

I have an array of structs in ColdFusion. I\'d like to sort this array based on one of the attributes in the structs. How can I achieve this? I\'ve found the StructSort fun

Answer 1

The accepted solution (from CFLib.org) is NOT safe. I experimented with this for something I needed to do at work and found that it returns incorrect results when sorting numeric with floats.

For example if I have these structs: (pseudocode)

a = ArrayNew(1);

s = StructNew();
s.name = 'orange';
s.weight = 200;
ArrayAppend(a, s);

s = StructNew();
s.name = 'strawberry';
s.weight = 28;
ArrayAppend(a, s);

s = StructNew();
s.name = 'banana';
s.weight = 90.55;
ArrayAppend(a, s);

sorted_array = arrayOfStructsSort(a, 'weight', 'asc', 'numeric');

Iterate over the sorted array and print the name & weight. It won't be in the right order, and this is a limitation of mixing an arbitrary key with the value being sorted.

Answer 2

Easy solution to sort an array of structures using more than one key using arraySort callback:

It takes array of structs to be sorted as first parameter and array of structs in format of sortkey/sortorder pair as second parameter e.g. [{sortkey: 'FirstName', sortorder: 'asc'}, {sortkey: 'LastName', sortorder: 'desc'}].

<cffunction name="arrayOfStructsSort" access="public" returntype="array" output="false" hint="This sorts an array of structures.">
    <cfargument name="aOfS" type="array" required="yes" />
    <cfargument name="key_sortOrder" type="array" required="yes" />
    <cfscript>

    arraySort(
        aOfS,
        function (a, b) {
            for (var i = 1; i lte arrayLen(key_sortOrder); i = i + 1) {
                var prop = key_sortOrder[i];
                var key = prop.key;
                var sortOrder = prop.sortOrder;
                if (a[key] lt b[key]) {
                    if (sortOrder eq 'desc') {
                        return 1;
                    } else {
                        return -1;
                    }
                }
                if (a[key] gt b[key]) {
                    if (sortOrder eq 'desc') {
                        return -1;
                    } else {
                        return 1;
                    }
                }
            }
            return 0;
        }
    );

    return aOfS;

    </cfscript>

</cffunction>

Simply call it with:

<cfset ArraySorted = arrayOfStructsSort(arrayToBeSorted,arrayOfSorkeys)>

Answer 3

In case you don't want to use custom methods, Coldfusion has structSort method http://www.cfquickdocs.com/cf8/#StructSort . Yes it sorts structure with nested structures, BUT returns array so could be used to achieve same result.

Answer 4

Here is something that closely resembles the original StructSort(). It also supports the pathToSubElement argument.

<cffunction name="ArrayOfStructSort" returntype="array" access="public" output="no">
  <cfargument name="base" type="array" required="yes" />
  <cfargument name="sortType" type="string" required="no" default="text" />
  <cfargument name="sortOrder" type="string" required="no" default="ASC" />
  <cfargument name="pathToSubElement" type="string" required="no" default="" />

  <cfset var tmpStruct = StructNew()>
  <cfset var returnVal = ArrayNew(1)>
  <cfset var i = 0>
  <cfset var keys = "">

  <cfloop from="1" to="#ArrayLen(base)#" index="i">
    <cfset tmpStruct[i] = base[i]>
  </cfloop>

  <cfset keys = StructSort(tmpStruct, sortType, sortOrder, pathToSubElement)>

  <cfloop from="1" to="#ArrayLen(keys)#" index="i">
    <cfset returnVal[i] = tmpStruct[keys[i]]>
  </cfloop>

  <cfreturn returnVal>
</cffunction>

Usage / test:

<cfscript> 
  arr = ArrayNew(1);

  for (i = 1; i lte 5; i = i + 1) {
    s = StructNew();
    s.a.b = 6 - i;
    ArrayAppend(arr, s);
  }
</cfscript> 

<cfset sorted = ArrayOfStructSort(arr, "numeric", "asc", "a.b")>

<table><tr>
  <td><cfdump var="#arr#"></td>
  <td><cfdump var="#sorted#"></td>
</tr></table>

Result: