[Couchdb Wiki] Update of "How_to_intercept_document_updates_and_perform_additional_server-side_processing" by SebastianCohnen

[Apache Wiki <wi...@apache.org>]

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Couchdb Wiki" for change notification.

The "How_to_intercept_document_updates_and_perform_additional_server-side_processing" page has been changed by SebastianCohnen.
The comment on this change is: added toc; syntax hl; cleanup.
http://wiki.apache.org/couchdb/How_to_intercept_document_updates_and_perform_additional_server-side_processing?action=diff&rev1=4&rev2=5

--------------------------------------------------

+ = Document Update Handlers =
+ <<TableOfContents()>>
+ 
  == Basics ==
  
  CouchDB (0.10 and up) has the ability to allow server-side processing of an incoming document before it's committed. This feature allows a range of use cases such as providing a server-side last modified timestamp, etc.
@@ -8, +11 @@

  
  This functionality is implemented via document update handlers defined in a design doc. Specifically, in a design doc one defines an "updates" attribute that contains any number of document update handlers. The follow handlers should be self-explanatory as to what they accomplish. 
  
- {{{
+ {{{#!highlight javascript
+ {
-     updates: {
+   updates: {
  
-       "hello" : function(doc, req) {
+     "hello" : function(doc, req) {
-         if (!doc) {
+       if (!doc) {
-           if (req.docId) {
+         if (req.docId) {
-             return [{
+           return [{
-               _id : req.docId
+             _id : req.docId
-             }, "New World"]
+           }, "New World"]
-           }
-           return [null, "Empty World"];          
          }
+         return [null, "Empty World"];          
+       }
-         doc.world = "hello";
+       doc.world = "hello";
-         doc.edited_by = req.userCtx;
+       doc.edited_by = req.userCtx;
-         return [doc, "hello doc"];
+       return [doc, "hello doc"];
-       },
+     },
  
-       "in-place" : function(doc, req) {
+     "in-place" : function(doc, req) {
-         var field = req.query.field;
+       var field = req.query.field;
-         var value = req.query.value;
+       var value = req.query.value;
-         var message = "set "+field+" to "+value;
+       var message = "set "+field+" to "+value;
-         doc[field] = value;
+       doc[field] = value;
-         return [doc, message];
+       return [doc, message];
-       },
+     },
  
-       "bump-counter" : function(doc, req) {
+     "bump-counter" : function(doc, req) {
-         if (!doc.counter) doc.counter = 0;
+       if (!doc.counter) doc.counter = 0;
-         doc.counter += 1;
+       doc.counter += 1;
-         var message = "<h1>bumped it!</h1>";
+       var message = "<h1>bumped it!</h1>";
-         return [doc, message];
+       return [doc, message];
-       },
+     },
  
-       "error" : function(doc, req) {
+     "error" : function(doc, req) {
-         superFail.badCrash;
+       superFail.badCrash;
-       },
+     },
  
-       "xml" : function(doc, req) {
+     "xml" : function(doc, req) {
-         var xml = new XML('<xml></xml>');
+       var xml = new XML('<xml></xml>');
-         xml.title = doc.title;
+       xml.title = doc.title;
-         var posted_xml = new XML(req.body);
+       var posted_xml = new XML(req.body);
-         doc.via_xml = posted_xml.foo.toString();
+       doc.via_xml = posted_xml.foo.toString();
-         var resp =  {
+       var resp =  {
-           "headers" : {
+         "headers" : {
-             "Content-Type" : "application/xml"
+           "Content-Type" : "application/xml"
-           },
+         },
-           "body" : xml
+         "body" : xml
-         };
+       };
-          
+      
-          return [doc, resp];
+        return [doc, resp];
-        }
-     }
+      }
+   }
+ }
  }}}
  
  The handler function takes the document and the http request as parameters. It returns a two-element array: the first element is the (updated) document, which is committed to the database. The second element is the response that will be sent back to the caller.