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The page "EnableErlangViews" has been deleted by JoanTouzet: https://wiki.apache.org/couchdb/EnableErlangViews?action=diff&rev1=6&rev2=7 Comment: Migrated to https://docs.couchdb.org/en/latest/config/query-servers.html - <<Include(EditTheWiki)>> - = How to Enable Erlang Views = - Since version 0.10.0, CouchDB has a native Erlang view server, allowing you to write your map/reduce functions in Erlang. There is no-longer the need to manually install [[http://github.com/mmcdanie/erlview|erlview]], unless you are running an old version of CouchDB. - - First, you'll need to edit your `local.ini` to include a native_query_servers section: - - {{{ - [native_query_servers] - erlang = {couch_native_process, start_link, []} - }}} - Your `local.ini` will most likely be at `/usr/local/etc/couchdb/local.ini` or `/etc/couchdb/local.ini`. To see these changes you will also need to restart the server: - - {{{ - sudo /etc/init.d/couchdb restart - }}} - To test out using Erlang views, visit the Futon admin interface, create a new database and open a temporary view. You should now be able to select erlang from the language drop-down. - - Let's try an example of map/reduce functions which count the total documents at each number of revisions (there are x many documents at version "1", and y documents at "2"... etc). Add a few documents to the database, then enter the following functions as a temporary view: - - {{{ - %% Map Function - fun({Doc}) -> - <<K,_/binary>> = proplists:get_value(<<"_rev">>, Doc, null), - V = proplists:get_value(<<"_id">>, Doc, null), - Emit(<<K>>, V) - end. - - %% Reduce Function - fun(Keys, Values, ReReduce) -> length(Values) end. - }}} - If all has gone well, after running the view you should see a list of the total number of documents at each revision number. - - == Filters == - A simple "doc-type filter" ([[http://mail-archives.apache.org/mod_mbox/couchdb-user/201302.mbox/<CAFZfYnDo-Z=vz0acphj-lk6zbp-3wz_x0rcw4basqnvush8...@mail.gmail.com>|source]]) - - {{{ - fun({Doc}, {Req}) -> - DocType = couch_util:get_value(<<"type">>, Doc), - case DocType of - undefined -> false; - <<"mytype">> -> true; - _ -> false - end - end. - }}} - Another filter example that receives a values query parameter (comma separated), and lets through any design docs, any _deleted docs, and the mytype doc only if its value propery is contained in the query parameter ([[http://mail-archives.apache.org/mod_mbox/couchdb-user/201302.mbox/<CAFZfYnDo-Z=vz0acphj-lk6zbp-3wz_x0rcw4basqnvush8...@mail.gmail.com>|source]]) - - {{{ - fun({Doc}, {Req}) -> - DocId = couch_util:get_value(<<"_id">>, Doc), - DocType = couch_util:get_value(<<"type">>, Doc), - DocValue = couch_util:get_value(<<"value">>, Doc), - DocDeleted = couch_util:get_value(<<"_deleted">>, Doc), - - {Query} = couch_util:get_value(<<"query">>,Req, {[]}), - ValuesParam = couch_util:get_value(<<"values">>,Query), - Values = binary:split(ValuesParam, <<",">>, [global]), - case {DocId, DocDeleted} of - {<<"_design/", _/binary>>, _} -> true; - {_, true} -> true; - _ -> - case DocType of - undefined -> false; - <<"mytype">> -> lists:any(fun(E) -> E =:= DocValue - end, Values); - _ -> false - end - end - end. - }}} -
