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Date: Tue, 25 Aug 2009 15:09:16 -0400
Message-ID: <e2111bbb0908251209v68903f18x1419c2c7798651ec@mail.gmail.com>
Subject: Re: Understanding couchdb error messages
From: Paul Davis <paul.joseph.davis@gmail.com>
To: user@couchdb.apache.org
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On Tue, Aug 25, 2009 at 3:02 PM, Hadley Wickham<hadley@rice.edu> wrote:
> Hi all,
>
> Do you have any tips to offer on interpreting couch db error messages?
> =A0For example, take the error below:
>
> =3DERROR REPORT=3D=3D=3D=3D 25-Aug-2009::13:58:08 =3D=3D=3D
> ** Generic server <0.20641.8> terminating
> ** Last message in was {'EXIT',<0.20640.8>,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {{badmatch,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0<<"Cannot =
encode 'undefined' value as JSON">>},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0[{couch_query_serv=
ers,reduce,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_view_group=
,'-init_group/4-fun-0-',4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,'-wr=
ite_node/3-lc$^0/1-0-',3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,writ=
e_node,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,modi=
fy_node,4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,quer=
y_modify,4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,add_=
remove,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_view_updat=
er,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 '-write_c=
hanges/4-lc$^3/1-3-',2}]}}
> ** When Server state =3D=3D {file_descriptor,prim_file,{#Port<0.1471>,18}=
}
> ** Reason for termination =3D=3D
> ** {{badmatch,<<"Cannot encode 'undefined' value as JSON">>},
> =A0 =A0[{couch_query_servers,reduce,3},
> =A0 =A0 {couch_view_group,'-init_group/4-fun-0-',4},
> =A0 =A0 {couch_btree,'-write_node/3-lc$^0/1-0-',3},
> =A0 =A0 {couch_btree,write_node,3},
> =A0 =A0 {couch_btree,modify_node,4},
> =A0 =A0 {couch_btree,query_modify,4},
> =A0 =A0 {couch_btree,add_remove,3},
> =A0 =A0 {couch_view_updater,'-write_changes/4-lc$^3/1-3-',2}]}
> 1> [error] [<0.20641.8>] {error_report,<0.25.0>,
> =A0 =A0{<0.20641.8>,crash_report,
> =A0 =A0 [[{initial_call,{couch_file,init,['Argument__1']}},
> =A0 =A0 =A0 {pid,<0.20641.8>},
> =A0 =A0 =A0 {registered_name,[]},
> =A0 =A0 =A0 {error_info,
> =A0 =A0 =A0 =A0 =A0 {exit,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 {{badmatch,<<"Cannot encode 'undefined' value=
 as JSON">>},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0[{couch_query_servers,reduce,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_view_group,'-init_group/4-fun-0-',=
4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,'-write_node/3-lc$^0/1-0-',3=
},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,write_node,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,modify_node,4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,query_modify,4},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_btree,add_remove,3},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {couch_view_updater,'-write_changes/4-lc$=
^3/1-3-',2}]},
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 [{gen_server,terminate,6},{proc_lib,init_p_do=
_apply,3}]}},
> =A0 =A0 =A0 {ancestors,
> =A0 =A0 =A0 =A0 =A0 [<0.20640.8>,couch_view,couch_secondary_services,couc=
h_server_sup,
> =A0 =A0 =A0 =A0 =A0 =A0<0.1.0>]},
> =A0 =A0 =A0 {messages,[]},
> =A0 =A0 =A0 {links,[#Port<0.1471>]},
> =A0 =A0 =A0 {dictionary,[]},
> =A0 =A0 =A0 {trap_exit,true},
> =A0 =A0 =A0 {status,running},
> =A0 =A0 =A0 {heap_size,1597},
> =A0 =A0 =A0 {stack_size,24},
> =A0 =A0 =A0 {reductions,462029}],
> =A0 =A0 =A0[]]}}
>
> I can see that the basic problem appears to be "Cannot encode
> 'undefined' value as JSON", but how can I tell which view is having
> this problem, and which particular record is causing the problem?
>
> This should be really easy for me to figure out given that I only have
> two views. I'm using one to create a index so I can look articles up
> by keywords:
>
> map: function(doc) {
> =A0for(i in doc.keywords) {
> =A0 =A0emit(doc.keywords[i], null)
> =A0}
> }
>
> and the other just to count the number of articles that use a keyword:
>
> map: function(doc) {
> =A0for(i in doc.keywords) {
> =A0 =A0emit(doc.keywords[i], 1)
> =A0}
> }
>
> reduce: function(keys, values, rereduce) {
> =A0sum(values)
> }
>
> What am I doing wrong?
>
> Thanks!
>
> Hadley
> --
> http://had.co.nz/
>

The important bit:

<<"Cannot encode 'undefined' value as JSON">>

Means we're missing something in the view server, but the underlying
cause is that you're accessing a JavaScript member that doesn't exist.
Something like:

var f =3D {"stuff": "here"};
emit(f.not_an_member, null);

Both of your maps look all right though. Is that all there is, or is
there something else that wasn't pasted?

HTH,
Paul Davis