CODEWITHSUNDEEP
javascriptvalidationcouchdb
Skitterm
Skitterm

Reputation: 4575

loop through CouchDB fields in document (validate_doc_update)

I am trying to loop through the fields in a CouchDB document and check that the old version of the field and new version are the same (as part of my validate_doc_update). However, I would like to do the equivalent of a "foreach field in documents, check to make sure they are the same", instead of having to say something like

oldrev.document.field1 == newrev.document.field1, oldrev.document.field2 == newrev.document.field2,

blah blah. Is there a way to do this with CouchDB fields, or do I have to specify the name of each field? It would be nice to not type them all in, and if we ever change the field names, to not have to come back in and tweak things.

Upvotes: 1

Views: 1335

Answers (2)

Marcello Nuccio
Marcello Nuccio

Reputation: 3901

The values passed as newDoc, and oldDoc parameters to validate_doc_update function are Javascript objects: you compare two documents as you compare any JS objects. There no "CouchDB field".

You can write custom code, or you can use a JS library like Underscore.js. You can include it as a CommonJS module. The only problem is the _rev field. My approach is to keep CouchDB metadata separate from document data, by putting the data in a data field. For example:

{ "_id": "ID", "_rev": "REV", "foo": "bar", "baz": [1, 2] }

becomes

{ "_id": "ID", "_rev": "REV", "data": { "foo": "bar", "baz": [1, 2] } }

Then the comparison can be done with

function(newDoc, oldDoc) {
  var _ = require("underscore");
  if (!_.isEqual(newDoc.data, oldDoc.data)) {
    // something changed...
  }
}

Upvotes: 1

Dominic Barnes
Dominic Barnes

Reputation: 28429

A JS for in loop should suffice:

for (var key in newrev) {
    if (newrev.hasOwnProperty(key) {
        if (oldrev[key] === newrev[key]) {
            // they are the same
        }
    }
}

There is one thing you'll need to be cautious of here, and that is that deleting/adding fields between revisions may be harder to validate.

I'm pretty sure Object.keys is available to SpiderMonkey, so you may need to use that to compare the number of keys between old and new.

Upvotes: 1

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