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ColdFusion 10: Making REST Pathparams optional

I was working on creating a CRUD application with REST and wanted to retrieve records with a GET request. The GET request would contain the ARTID for which the record has to be retrieved in the URL itself. To do this I had added an argument to the method implementing the GET request with ‘restargsource’ attribute set to path. The URL would be of the form:

http://localhost:8500/rest/restapp/artService/getart/1

However, in another scenario I wanted to retrieve all the records from the ART table when there is no ARTID specified in the URI i.e. with the URL:

http://localhost:8500/rest/restapp/artService/getart/

PathParams are always required and if they’re not specified then a ‘404 Not found’ error would be thrown. I thought of adding another method to handle this GET request with no PathParams. But, it would have made my code look clumsy and semantically not correct. However, I was able resolve this by providing a regular expression for the PathParam argument.

In REST, PathParams can have a regular expression assigned to them. For example, if a PathParam argument say 'name' would contain only alphabets then the regular expression [a-zA-Z] would match the restpath. Here the restpath attribute would be {name: [a-zA-Z]}. Similarly the regular expression for optional data would be ([0-9])*.

<cfcomponent restpath="/artService"> <cffunction name="getRequestHandler" access="remote" httpmethod="GET" returntype="query" produces="application/json" restpath="/getart/{artid: ([0-9])*}"> <cfargument name="artid" type="string" restargsource="path" required="false"/> <!--- execute when ARTID is specified in the path ---> <cfif len(arguments.artid) GT 0> <cfquery name="qdata"> select ARTID, ARTNAME, DESCRIPTION from ART where ARTID =<cfqueryparam value="#arguments.artid#"> </cfquery> <cfelse> <!--- execute when ARTID is not specified in the path ---> <cfquery name="qdata"> select ARTID, ARTNAME, DESCRIPTION from ART </cfquery> </cfif> <cfreturn qdata> </cffunction> </cfcomponent>


In the above code snippet the restpath is '/getart/{artid: ([0-9])*}'. If ARTID is not specified in the URL then all the records from the ART table would be fetched and returned to the client in application/json format. In case the ARTID is specified then only the records matching the specified ARTID would be returned to the client.
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Comments

  1. AJ MercerMay 29, 2012 at 12:53 AM

    Would you not just have two funtions,one with restpath="/getart"
    And the other with restpath="/getart/ ...

    ReplyDelete
  2. Sagar GanatraMay 29, 2012 at 9:35 AM

    @AJ Mercer , you're right that's another way of doing it. But what I wanted to demonstrate was to use regular expressions do define a pattern for the arguments. And of course not to repeat the code.

    ReplyDelete

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