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Message-ID: <e282921e0808062057h31ea4e33lbd360917a7431e67@mail.gmail.com>
Date: Wed, 6 Aug 2008 20:57:55 -0700
From: "Chris Anderson" <jchris@grabb.it>
Sender: jchris@gmail.com
To: couchdb-dev@incubator.apache.org
Subject: Re: [PATCH] Views: Multiple keys
In-Reply-To: <20080723053624.GA8963@pib-laptop>
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References: <20080723053624.GA8963@pib-laptop>

Thanks for the patch Paul. I updated it against current trunk and
added some unit tests to it. I took the opportunity to do some
refactoring and create a output_map_view function. It's working well
for design docs but for some reason I can't get it to behave correctly
with _temp_views.

The behavior is documented in the attached unit tests, but the gist of
it is that POSTs to /mydb/_view/design/view with a body like:
{"keys":[array of keys]}
return just the view rows that match the keys. There is still work to
be done to test the interactions with other request params. I started
down the path of getting reduce functions to work with keys as well,
but I think that will require getting deep into couch_btree.erl

The patch is here:

http://friendpaste.com/7Va7jgWK

If anyone can apply it and try to figure out the temp-view stuff,
that'd be super helpful. Otherwise maybe sleep and a fresh look will
let me finish it.

Chris

On Tue, Jul 22, 2008 at 10:36 PM, Paul Bonser <misterpib@gmail.com> wrote:
> After exploring the source code a bit and abandoning a few other ways of achieving this, I've managed to get multi-key requests working. The only way to make it more efficient would require some digging into the couch_btree folding code, I think.
>
> You use it by POSTing a JSON array of keys to a view url. Any passed-in values for start_key and end_key are ignored.
>
> I haven't written any unittests for this yet, but I wanted to see what everyone else thinks of this and ask if there's any obvious better way to accomplish the same goal.
>
> This patch is against the latest in SVN as of now. Any comments or suggestions for this are very much welcome.
>
>
> Signed-off-by: Paul Bonser <misterpib@gmail.com>
> --
>
> diff --git a/src/couchdb/couch_httpd.erl b/src/couchdb/couch_httpd.erl
> index af8d9b4..c813a4c 100644
> --- a/src/couchdb/couch_httpd.erl
> +++ b/src/couchdb/couch_httpd.erl
> @@ -363,6 +363,37 @@ handle_db_request(Req, 'GET', {DbName, _Db, ["_view", DocId, ViewName]}) ->
>         end
>     end;
>
> +% Multi-key request, with a JSON array of keys as the POST body
> +handle_db_request(Req, 'POST', {DbName, _Db, ["_view", DocId, ViewName]}) ->
> +    #view_query_args{
> +        count = Count,
> +        skip = SkipCount,
> +        direction = Dir,
> +        start_docid = StartDocId
> +    } = QueryArgs = parse_view_query(Req),
> +
> +    case Req:get_primary_header_value("content-type") of
> +        undefined -> ok;
> +        "application/json" -> ok;
> +        Else -> throw({incorrect_mime_type, Else})
> +    end,
> +       JsonKeys = tuple_to_list(cjson:decode(Req:recv_body())),
> +
> +    {ok, View} = couch_view:get_map_view({DbName, "_design/" ++ DocId, ViewName}),
> +    {ok, RowCount} = couch_view:get_row_count(View),
> +    FoldAccInit = {Count, SkipCount, undefined, []},
> +    FoldResult = lists:foldl(fun(Key, {ok, FoldAcc}) ->
> +        Start = {Key, StartDocId},
> +        FoldlFun = make_view_fold_fun(Req, QueryArgs#view_query_args {
> +                    start_key = Key,
> +                    end_key = Key
> +                },
> +                RowCount, fun couch_view:reduce_to_count/1),
> +        couch_view:fold(View, Start, Dir, FoldlFun, FoldAcc)
> +    end, {ok, FoldAccInit}, JsonKeys),
> +    finish_view_fold(Req, RowCount, FoldResult);
> +
> +
>  handle_db_request(_Req, _Method, {_DbName, _Db, ["_view", _DocId, _ViewName]}) ->
>     throw({method_not_allowed, "GET,HEAD"});
>
>


-- 
Chris Anderson
http://jchris.mfdz.com