[jira] [Resolved] (COUCHDB-1506) View returns null value after adding a document

["Robert Newson (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COUCHDB-1506?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Newson resolved COUCHDB-1506.
------------------------------------

    Resolution: Invalid

The user's reduce function does not anticipate receiving some of values emitted by the corresponding map function, causing algorithmic expectations to fail.
                
> View returns null value after adding a document
> -----------------------------------------------
>
>                 Key: COUCHDB-1506
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1506
>             Project: CouchDB
>          Issue Type: Bug
>          Components: JavaScript View Server
>    Affects Versions: 1.2
>         Environment: Windows XP SP3
>            Reporter: Marcin Stefaniuk
>
> I have three types of documents: customer, refill and purchase. I defined a view that aggregates customer data with current balance (from refill / purchase values). Values customer._id and purchase/refill.customer are joining keys. Map function looks as follows:
> function(doc) {
>   if (doc.type=='purchase' || doc.type=='refill') {
>     emit(doc.customer, {value: doc.value, type: doc.type});
>   } else if (doc.type=='customer') {
>     emit(doc._id, doc);
>   }
> }
> Reduce function is:
> function(keys, values, rereduce) {
>   var customer = null, sum = 0;
>   values.forEach(function(element) {
>     if (element.type=='purchase') {
>       sum -= element.value;
>     } else if (element.type=='refill') {
>       sum += element.value;
>     } else if (customer==null && element.type=='customer') {
>       customer = element;
>     }
>   });
>   customer.credit = sum;
>   return customer;
> }
> This view is working with success but after several adding of purchase documents it returns null as value.

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