ColdFusion's JSON Prefix feature - more than AJAX

That’s a pretty poor title, but hopefully things will make more sense when I explain it. Earlier this week I blogged about JSON prefixes and how you could handle them in jQuery and jQuery UI. While not specifically a ColdFusion topic, it was easy to test since ColdFusion has a feature where it can automatically prefix your JSON strings. This can be done at the server level, application level, and even the method level if you want. So given a CFC that returns some data, if you enable this feature and use the default prefix of //, your JSON may look like this:


No big deal. You can easily work around it. But here’s what surprised me. I had always assumed this was for Ajax services only. By that I mean, given a CFC that returns data, if this feature is on and I request the CFC with returnformat=json, I’d expect that to be the only place where the prefix is added. Not true! Consider this:

<cfset d = {x=[1,2,3],y="ray"}> <cfoutput>#serializejson(d)#</cfoutput>

In this snippet, which has nothing to do with Ajax, nothing to do with remote CFC calls, the JSON string is also prefixed with //. Admittedly I can’t think of many situations where I’m not using JSON for Ajax, but the point is, I did not expect this. Am I alone in this?

My recommendation is - you probably want to explicitly disable this feature in your Application.cfc file if you don’t want to use it. Anyone who develops open source code or code that a client may put on a shared host will probably want to ensure the feature isn’t enabled by accident.

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About Raymond Camden

Raymond is a developer advocate. He focuses on JavaScript, serverless and enterprise cat demos. If you like this article, please consider visiting my Amazon Wishlist or donating via PayPal to show your support.

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