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ColdFusion 10: Returning Complex data from a REST service

There are various complex types in ColdFusion – Array, Struct, Query. When a REST service in ColdFusion returns one of these complex types, it has to be serialized to either JSON or XML format. As explained in my previous post, the HTTP protocol can be used in content type negotiation. You can specify the desired content type either by specifying it at the end of the URL or in the Accept header of HTTP request. In this post, I’ll explain the format in which the complex types are returned from a ColdFusion REST service.

JSON format:
Consider the following REST service:
<cfcomponent rest="true" restpath="/jsonSerialization" produces="application/JSON"> <cffunction name="structSerialization" access="remote" httpmethod="GET" returntype="Struct" restpath="serializeStruct"> <cfset myStruct = StructNew()> <cfset myStruct.productName = "ColdFusion"> <cfset myStruct.productVersion = 10> <cfset myStruct.codeName = "Zeus"> <cfreturn myStruct> </cffunction> <cffunction name="querySerialization" access="remote" httpmethod="GET" returntype="Query" restpath="serializeQuery"> <cfset myQuery = queryNew("productName,version,codeName", "Varchar,Integer,Varchar", [["ColdFusion", 9, "Centaur"], ["ColdFusion", 10, "Zeus"]])> <cfreturn myQuery> </cffunction> <cffunction name="arraySerialization" access="remote" httpmethod="GET" returntype="Array" restpath="serializeArray"> <cfset myArray = ArrayNew(2)> <cfset ArrayAppend(myArray, ["ColdFusion", 9, "Centaur"])> <cfset ArrayAppend(myArray, ["ColdFusion", 10, "Zeus"])> <cfreturn myArray> </cffunction> <cffunction name="cfcSerialization" access="remote" httpmethod="GET" returntype="TestComponent" restpath="serializeCFC"> <cfset obj = new TestComponent()> <cfset obj.prop1 = "CF"> <cfset obj.prop2 = "Zeus"> <cfreturn obj> </cffunction> </cfcomponent>
As you can see, the produces attribute is specified at the component level and not at the function level. This indicates that all the services in this component produce or return data in the specified format(application/json here). However, if the produces attribute is specified at both component and at the function level then the one specified at the function level would take precedence.
The complex types – Array, Struct, Query as well as a CFC can be serialized to a JSON format. The above REST service is invoked using CFHTTP with the URI: http://localhost:8500/rest/complexTypes/jsonSerialization/serializeQuery.json (to obtain query data) and then the result is de-serialized to obtain the below output:
Query_Serialized_JSON
The above struct contains the query data as well as the columns.

XML format:
Similar to the JSON format, if the produces attributes’ value is changed to application/XML then the complex data returned from a REST service is serialized to XML format. Here is the output obtained by invoking the REST service to obtain the CFC data serialized to XML format:

<COMPONENT ID="1" NAME="restapp.ComplexTypes.TestComponent">
<PROPERTY NAME="PROP1" TYPE="STRING">CF</PROPERTY>
<PROPERTY NAME="PROP2" TYPE="STRING">Zeus</PROPERTY>
</COMPONENT>

Similarly other complex data types can be serialized to JSON or XML format.
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