On 20 Apr 2011, at 14:11, Nils Breunese wrote:
> Hello all,
>
> I recently upgraded to CouchDB 1.0.2 for development and found some of our
> view map functions broke. Apparently it's no longer possible to modify data a
> doc in a view function before emitting. I found "Documents are now sealed
> before being passed to map functions." in the changelog for 1.0.2.
>
> This is an example of a map function which no longer works under 1.0.2:
>
> ----
> function(doc) {
> if(doc.type === 'schedule') {
> var events = doc.events;
> if (events) {
> events.forEach(function(event) {
> var broadcasters = event.broadcasters;
> if (broadcasters) {
> broadcasters.forEach(function(broadcaster) {
> if(broadcaster === 'VPRO') {
> event.channel = doc.channel;
> event.channelName = doc.channelName;
> emit(event.end, event);
> }
> });
> }
> });
> }
> }
> }
> ----
>
> A colleague suggested using this:
>
> ----
> events.forEach(function(e) {
> var event = eval(uneval(e));
> ----
>
> This creates a deep copy before modifying event properties. It works, but it
> looks ugly to me. Is this the way to go or is there a cleaner way?
I use JSON.parse(JSON.stringify(doc)) but that is essentially the same :)
The reason that doc modifications work were an artefact of a bug in
Spidermonkey that finally got resolved. You shouldn't rely on being able to
modify a doc in map functions.
That said, I'm surprised you get this error as you are not assigning anything
do doc.events. Unless I got wrong how chaining in JS works, this shouldn't be a
problem:
js> var a = {a:1};
js> seal(a);
js> a.a = 2;
typein:4: Error: a.a is read-only
js> var b = a.a;
js> print(b);
1
js> b = 2
2
js>
Cheers
Jan
--
