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    <p>In a recent project ive worked on, we were dealing with big JSON data structures coming from <b><a href="http://docs.sencha.com/ext-js/4-0/" rel="nofollow">EXT JS</a></b> front end apps. One example of the JSON object is here below (this is just the skeleton of the JSON ):</p> <pre> { "presence_token":"734737328233HDHSBSHSYEYEYWYWGWE", "presence_time":"HH:Mins:Secs", "friend_requests": [ { "from":"Username", "type":"buddy", "date":"DD/MM/YY", "time":"HH:Mins:Secs", "name":"Your Full name", "email":"user@example.com" } ], "group_status": [ { "group_name":"ecampus", "status":"running", "members":["phil","josh","shazz"], "start_date":"DD/MM/YY", "start_time":"HH:Mins:Secs" }, { "group_name":"buganda", "status":"off" } ], "friend_status": [ { "friend":"Friend_username", "status":"online", "log_on_time":"HH:Mins:Secs", "state":"available", "name":"Friend_Fullname", "email":"user@example.com" }, { "friend":"Friend_username", "status":"offline", "name":"Friend_Fullname", "email":"user@example.com" } ] } </pre> <p>After <code>mochijson2:decode/1</code>, the struct object i had appears like this:</p> <pre> {struct,[{&lt;&lt;"presence_token"&gt;&gt;, &lt;&lt;"734737328233HDHSBSHSYEYEYWYWGWE"&gt;&gt;}, {&lt;&lt;"presence_time"&gt;&gt;,&lt;&lt;"HH:Mins:Secs"&gt;&gt;}, {&lt;&lt;"friend_requests"&gt;&gt;, [{struct,[{&lt;&lt;"from"&gt;&gt;,&lt;&lt;"Username"&gt;&gt;}, {&lt;&lt;"type"&gt;&gt;,&lt;&lt;"buddy"&gt;&gt;}, {&lt;&lt;"date"&gt;&gt;,&lt;&lt;"DD/MM/YY"&gt;&gt;}, {&lt;&lt;"time"&gt;&gt;,&lt;&lt;"HH:Mins:Secs"&gt;&gt;}, {&lt;&lt;"name"&gt;&gt;,&lt;&lt;"Your Full name"&gt;&gt;}, {&lt;&lt;"email"&gt;&gt;,&lt;&lt;"user@example.com"&gt;&gt;}]}]}, {&lt;&lt;"group_status"&gt;&gt;, [{struct,[{&lt;&lt;"group_name"&gt;&gt;,&lt;&lt;"ecampus"&gt;&gt;}, {&lt;&lt;"status"&gt;&gt;,&lt;&lt;"running"&gt;&gt;}, {&lt;&lt;"members"&gt;&gt;,[&lt;&lt;"phil"&gt;&gt;,&lt;&lt;"josh"&gt;&gt;,&lt;&lt;"shazz"&gt;&gt;]}, {&lt;&lt;"start_date"&gt;&gt;,&lt;&lt;"DD/MM/YY"&gt;&gt;}, {&lt;&lt;"start_time"&gt;&gt;,&lt;&lt;"HH:Mins:Secs"&gt;&gt;}]}, {struct,[{&lt;&lt;"group_name"&gt;&gt;,&lt;&lt;"buganda"&gt;&gt;}, {&lt;&lt;"status"&gt;&gt;,&lt;&lt;"off"&gt;&gt;}]}]}, {&lt;&lt;"friend_status"&gt;&gt;, [{struct,[{&lt;&lt;"friend"&gt;&gt;,&lt;&lt;"Friend_username"&gt;&gt;}, {&lt;&lt;"status"&gt;&gt;,&lt;&lt;"online"&gt;&gt;}, {&lt;&lt;"log_on_time"&gt;&gt;,&lt;&lt;"HH:Mins:Secs"&gt;&gt;}, {&lt;&lt;"state"&gt;&gt;,&lt;&lt;"available"&gt;&gt;}, {&lt;&lt;"name"&gt;&gt;,&lt;&lt;"Friend_Fullname"&gt;&gt;}, {&lt;&lt;"email"&gt;&gt;,&lt;&lt;"user@example.com"&gt;&gt;}]}, {struct,[{&lt;&lt;"friend"&gt;&gt;,&lt;&lt;"Friend_username"&gt;&gt;}, {&lt;&lt;"status"&gt;&gt;,&lt;&lt;"offline"&gt;&gt;}, {&lt;&lt;"name"&gt;&gt;,&lt;&lt;"Friend_Fullname"&gt;&gt;}, {&lt;&lt;"email"&gt;&gt;,&lt;&lt;"user@example.com"&gt;&gt;}]}]}]} </pre> <p>Now i decided to create a module which will convert this struct into a "deep" proplist, this module would contain a function <code>struct:all_keys/1</code> which if i feed it with the struct object it generates lists and tuples in an organised way. Here is the code:</p> <pre> -module(struct). -export([all_keys/1]). is_struct({struct,_}) -&gt; true; is_struct(_) -&gt; false. to_binary(S) when is_list(S)-&gt; list_to_binary(S); to_binary(S) when is_integer(S)-&gt; S; to_binary(S) when is_atom(S)-&gt; to_binary(atom_to_list(S)); to_binary(S) -&gt; S. to_value(V) when is_binary(V)-&gt; binary_to_list(V); to_value(V) when is_integer(V)-&gt; V; to_value(V) when is_list(V)-&gt; try list_to_integer(V) of PP -&gt; PP catch _:_ -&gt; try list_to_float(V) of PP2 -&gt; PP2 catch _:_ -&gt; V end end; to_value(A)-&gt; A. to_value2({struct,L})-&gt; all_keys({struct,L}); to_value2([{struct,_L}|_Rest] = LL)-&gt; [all_keys(XX) || XX &lt;- LL]; to_value2(D) when is_binary(D)-&gt; to_value(D); to_value2(D) when is_list(D)-&gt; [to_value2(Any) || Any &lt;- D]. all_keys({struct,L})-&gt; [{to_value(Key),to_value2(Val)} || {Key,Val} &lt;- L]; all_keys(List)-&gt; [all_keys(X) || X &lt;- List]. </pre> <p>Now, calling <code>struct:all_keys(Struct_object)</code> will give this output:</p> <pre> [{"presence_token",P_token}, {"presence_time",P_time}, {"friend_requests", [[{"from","Username"}, {"type","buddy"}, {"date","DD/MM/YY"}, {"time","HH:Mins:Secs"}, {"name","Your Full name"}, {"email","user@example.com"}]]}, {"group_status", [[{"group_name","ecampus"}, {"status","running"}, {"members",["phil","josh","shazz"]}, {"start_date","DD/MM/YY"}, {"start_time","HH:Mins:Secs"}], [{"group_name","buganda"},{"status","off"}]]}, {"friend_status", [[{"friend","Friend_username"}, {"status","online"}, {"log_on_time","HH:Mins:Secs"}, {"state","available"}, {"name","Friend_Fullname"}, {"email","user@example.com"}], [{"friend","Friend_username"}, {"status","offline"}, {"name","Friend_Fullname"}, {"email","user@example.com"}]]}] </pre> <p>The above proplist is easier to work with than the struct object. However, you may find another version of the struct module especially in a famous mochiweb example called Sticky Notes whose link i do not have right now.The struct module i have pasted above should be able to help you with using mochijson2. success</p>
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    1. POHow to pattern match structures returned by mochijson2?
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    1. USMuzaaya Joshua
    1. USMuzaaya Joshua
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    1. COI have tried to use your code, and found one mistake. There are two "[[" before "{"from","Username"}. But the code is very helpful for further modification.
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      1. USChen Yu
 

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