Treat output rows of views as documents for other views to build upon
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Key: COUCHDB-249
URL: https://issues.apache.org/jira/browse/COUCHDB-249
Project: CouchDB
Issue Type: New Feature
Reporter: Joey Lawrance
Unless I manually copy the JSON rows of a view into a new document, I am unable
to create new views that are computed from existing views. That is, it seems as
if views are second class citizens compared to first-class documents.
Suppose I wanted to find the spread between the cheapest suppliers and the most
expensive suppliers of each fruit. I know it's possible to use one map/reduce
to compute such a view, but I'd like to be able to re-use my existing
"cheapest" and "costliest" views. That is, I'd like to use the document output
of these views as input into another view.
I started with the simple fruit store example in the CouchDB book. I developed
a simple view called "cheapest" with the following map and reduce functions
(the "costliest" view is the same as "cheapest" but except the reduce
function's comparison is the other way around):
function(doc) {
var store, price, key;
if (doc.item && doc.prices) {
for (store in doc.prices) {
price = doc.prices[store];
key = doc.item;
emit(key, {store:store, price:price});
}
}
}
function(item,store) {
var m = store[0];
for (i in store) {
if (m.price > store[i].price) m = store[i];
}
return m;
}
The output is as follows:
{"rows":[
{"key":"apple","value":{"store":"Apples Express","price":0.79}},
{"key":"banana","value":{"store":"Price Max","price":079}},
{"key":"orange","value":{"store":"Citrus Circus","price":1.09}}
]}
I'd like to develop a new view whose input is the output of the view above, but
as far as I can tell, views only operate on documents, not the output of
existing views. Am I missing something?
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