Validate_Doc_Update

[TAE JIN KIM]

Hello,

Since CouchDB provides validate_doc_update, I thought that I might be able to 
provide some to check duplication here..
like...

function(newDoc,oldDoc,userCtx) {
      if(newDoc.type == "myCustomType") {
              // here..something like..
              // check newDoc against the existing documents of "myCustomType" 
to see whether there was already same data or not..
             // for example,
            //  
getExistingDocumentsByType("myCustomType").forEach(function(doc) {
           //               if(newDoc.mydata == doc.mydata) {
            //                       ///Boom..throw error..
             //              }
              //    });
           // 

Is this something possible? Well..obviously there is no provided 
getExistingDocumentsByType function from couchdb.....just was trying to show 
what I was trying to achieve...

So ultimately, my question is that..is there any way I can somehow access the 
existing documents from validate_doc_update function?

Thanks,