View query option defaults
--------------------------
Key: COUCHDB-1188
URL: https://issues.apache.org/jira/browse/COUCHDB-1188
Project: CouchDB
Issue Type: New Feature
Components: JavaScript View Server
Affects Versions: 1.0.2
Reporter: David Zülke
Priority: Minor
Fix For: 1.1.1
Currently, it's necessary to have intimate-ish knowledge of the inner workings
of a view when calling it, e.g.:
http://localhost:5984/mydb/_design/burp/_view/count-laser-beams?group_level=2
If the group level was different, the results returned by the view might be
useless.
Other good examples are "include_docs", "inclusive_end" or "descending". For
instance, views that pull in foreign documents by emitting {_id: ...} as a
value will only produce useful results when called with "include_docs" set to
true.
I'd suggest a feature where inside a view definition, a new key
"query_defaults" alongside "map" or "reduce" contains a hash map of query
option keys and values that will be used when calling the view unless one of
the pre-defined options is passed as a query argument, in which case the
explicitly given query argument would take precedence.
Example:
"views": {
"talks-by-room": {
"map": "function(doc) {\n\tif(doc.type == 'talk' && doc.date_start)
{\n\t\temit([doc.room, doc.date_start, 0], doc.name);\n\t\tif(doc.speaker)
{\n\t\t\temit([doc.room, doc.date_start, 1], {_id:
doc.speaker});\n\t\t}\n\t}\n};",
"query_defaults": {
"include_docs": true
}
}
}
http://localhost:5984/couchcamp/_design/burp/_view/talks-by-room would be run
with include_docs=true, but the doc inclusion could be suppressed by requesting
http://localhost:5984/couchcamp/_design/burp/_view/talks-by-room?include_docs=false
Alternative names for the new key are "query_options" or
"query_option_defaults". Whilst I prefer "query_options", I think
"query_defaults" will be the better choice as it underlines the nature of the
functionality - namely, that the options defined therein may be overridden by
the caller.
Someone on the dev list suggested to use _rewrite, but the idea is that the
defaults also apply when invoking a list function. So you'd need two rewrites,
one for the view if you want to call it standalone, and one for the list
function. And then you'd still have the issue that the behavior of the view is
changed by the rewrite, which is confusing to anyone looking at the view code -
you have to look at the rewrite as well to get the whole picture. Not good.
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