CB tutorial: Uncaught TypeError: Cannot read property 'length' of undefined

Romu

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Jan 14, 2014, 5:32:50 AM1/14/14

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Hi,

I was trying the example in CB tutorial "3. Implementing real-time updates with save hooks", below is my live.html:

<title>Fresh hot greetings!</title>

function listen_for_events(timestamp) {

$.ajax("/greeting/pull/"+timestamp, { success:

function(data, code, xhr) {

console.log(typeof data.greetings);

console.log(typeof data.greetings !== 'undefined' ? data.greetings.length : 'There is no spoon.');

for (var i=0; i<data.greetings.length; i++) {

var msg = data.greetings[i].greeting_text;

$("#greeting_list").append("<li>"+msg);

}

listen_for_events(data.timestamp);

} });

}

$(document).ready(function() {

listen_for_events({{ timestamp }});

});

</script>

</head>

<body>

{% for greeting in greetings %}

<li>{{ greeting.greeting_text }}

{% empty %}

<li>No greetings!

{% endfor %}

</ul>

</body>

</html>

When I create a new greeting, the live page does not update with the new greeting, in console I see javascript error:

Uncaught TypeError: Cannot read property 'length' of undefined live:10

$.ajax.success live:10

c jquery.js:3048

p.fireWith jquery.js:3160

k jquery.js:8235

r jquery.js:8778

Actually 'data' is undefined here.

Browser is Chrome 32.0.1700.72 m. I also tried jquery 1.70 and 2.0.3, same issue.

Any idea?

Thanks

Romu

can2nac

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Jan 14, 2014, 9:05:09 AM1/14/14

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Actually 'data' is undefined here. --- i think this is the key, post controller here.

Romu

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Jan 14, 2014, 9:35:37 PM1/14/14

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The controller (cb_tutorial_greeting_controller.erl):

-module(cb_tutorial_greeting_controller, [Req]).

-compile(export_all).

hello('GET', []) ->

{ok, [{greeting, "Hello, world!"}]}.

list('GET', []) ->

Greetings = boss_db:find(greeting, []),

{ok, [{greetings, Greetings}]}.

create('GET', []) ->

ok;

create('POST', []) ->

GreetingText = Req:post_param("greeting_text"),

NewGreeting = greeting:new(id, GreetingText),

case NewGreeting:save() of

{ok, SavedGreeting} ->

{redirect, [{action, "list"}]};

{error, ErrorList} ->

{ok, [{errors, ErrorList}, {new_msg, NewGreeting}]}

end.

goodbye('POST', []) ->

boss_db:delete(Req:post_param("greeting_id")),

{redirect, [{action, "list"}]}.

send_test_message('GET', []) ->

TestMessage = "Free at last!",

boss_mq:push("test-channel", TestMessage),

{output, TestMessage}.

pull('GET', [LastTimestamp]) ->

{ok, Timestamp, Greetings} = boss_mq:pull("new-greetings",

list_to_integer(LastTimestamp)),

{json, [{timestamp, Timestamp}, {greetings, Greetings}]}.

live('GET', []) ->

Greetings = boss_db:find(greeting, []),

Timestamp = boss_mq:now("new-greetings"),

{ok, [{greetings, Greetings}, {timestamp, Timestamp}]}.

And the model (greeting.erl):

-module(greeting, [Id, GreetingText]).

-compile(export_all).

validation_tests() ->

[{fun() -> length(GreetingText) > 0 end,

"Greeting must be non-empty!"},

{fun() -> length(GreetingText) =< 140 end,

"Greeting must be tweetable"}].

before_create() ->

ModifiedRecord = set(greeting_text,

re:replace(GreetingText,

"masticate", "chew",

[{return, list}])),

{ok, ModifiedRecord}.

after_create() ->

boss_mq:push("new-greetings", THIS).

Thanks

Romu

can2nac於 2014年1月14日星期二UTC+8下午10時05分09秒寫道：

Message has been deleted

can2nac

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Jan 15, 2014, 5:30:36 PM1/15/14

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check console, there are must be an error, at least i have one

23:50:49.116 [error] {function_clause,[{boss_json,json_data1,[[{greeting,"greeting-16","2"}],[],[]],[{file,"src/boss/boss_json.erl"},{line,23}]},{boss_json,json_data1,3,[{file,"src/boss/boss_json.erl"},{line,32}]},{boss_json,encode,2,[{file,"src/boss/boss_json.erl"},{line,9}]},{boss_web_controller,process_action_result,4,[{file,"src/boss/boss_web_controller.erl"},{line,1050}]},{boss_web_controller,execute_action,4,[{file,"src/boss/boss_web_controller.erl"},{line,882}]},{boss_web_controller,process_dynamic_request,4,[{file,"src/boss/boss_web_controller.erl"},{line,521}]},{boss_web_controller,process_request,4,[{file,"src/boss/boss_web_controller.erl"},{line,510}]},{timer,tc,3,[{file,"timer.erl"},{line,194}]}]}

if u have the same, then go to boss_json and check it.

best

On Tuesday, January 14, 2014 12:32:50 PM UTC+2, Romu wrote:

can2nac

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Jan 15, 2014, 5:33:56 PM1/15/14

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also there is some helping info in server response

http://localhost:8001/greeting/pull/1389825103565229

<html>

<head>

</head>

<body>

<h1>We got a problem!</h1>

<div class="alert alert-warning">This message will appear in production; you may want to define a 500 handler in /home/can2nac/projects/erlang/cb_tutorial/priv/cb_tutorial.routes</div>

<h2>Error:</h2>

<pre>{function_clause,

[{boss_json,json_data1,

[[{greeting,"greeting-31","test message\r\n"}],[],[]],

[{file,"src/boss/boss_json.erl"},{line,23}]},

{boss_json,json_data1,3,[{file,"src/boss/boss_json.erl"},{line,32}]},

{boss_json,encode,2,[{file,"src/boss/boss_json.erl"},{line,9}]},

{boss_web_controller,process_action_result,4,

[{file,"src/boss/boss_web_controller.erl"},{line,1050}]},

{boss_web_controller,execute_action,4,

[{file,"src/boss/boss_web_controller.erl"},{line,882}]},

{boss_web_controller,process_dynamic_request,4,

[{file,"src/boss/boss_web_controller.erl"},{line,521}]},

{boss_web_controller,process_request,4,

[{file,"src/boss/boss_web_controller.erl"},{line,510}]},

{timer,tc,3,[{file,"timer.erl"},{line,194}]}]}</pre>

<h2>Request:</h2>

<pre class=".pre-scrollable">{simple_bridge_request_wrapper,mochiweb_request_bridge,

{mochicow_request,#Port<0.61244>,'GET',"/greeting/pull/1389825103565229",

{1,1},

{10,

{"host",

{"host","localhost:8001"},

{"connection",

{"connection","keep-alive"},

{"cache-control",

{"cache-control","max-age=0"},

{"accept",

{"accept","*/*"},

nil,

{"accept-encoding",

{"accept-encoding","gzip,deflate,sdch"},

nil,

{"accept-language",

{"accept-language","ru,en-US;q=0.8,en;q=0.6"},

nil,nil}}},

nil},

{"dnt",{"dnt","1"},nil,nil}},

{"user-agent",

"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/31.0.1650.63 Chrome/31.0.1650.63 Safari/537.36"},

{"referer",

{"referer","http://localhost:8001/greeting/live"},

nil,nil},

{"x-requested-with",

{"x-requested-with","XMLHttpRequest"},

nil,nil}}}},

<<>>},

false,[],[],none}</pre>

<h2>Application info:</h2>

<pre class=".pre-scrollable">{boss_app_info,cb_tutorial,[],"/static","/doc",all,

[{cb_tutorial_01_news,[]}],

<0.348.0>,<0.349.0>,<0.351.0>,<0.352.0>,[],[],

["cb_tutorial_greeting_controller"]}</pre>

<p><em>Thu, 16 January 2014 12:31 a.m.</em></p>

</div>

</body>

On Tuesday, January 14, 2014 12:32:50 PM UTC+2, Romu wrote:

Romu

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Jan 15, 2014, 10:23:19 PM1/15/14

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I don't see this in my console. Are you suggesting that this may be caused by a bug in boss_json?

Thanks

Romu

can2nac於 2014年1月16日星期四UTC+8上午6時30分36秒寫道：

Romu

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Jan 15, 2014, 10:28:19 PM1/15/14

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I don't see this. The URL can't be opened.

BTW, I also tried the code with CB 0.8.9 and no luck.

Thanks

Romu

can2nac於 2014年1月16日星期四UTC+8上午6時33分56秒寫道：

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