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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.
