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Re: [json] Helpless beginner

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  • jon.erland.madsen@jiffymade.no
    Thank you so very much! I got help and will use the following code (my script is client side): ********************************************** function
    Message 1 of 8 , May 19, 2011
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      Thank you so very much!

      I got help and will use the following code (my script is client side):

      **********************************************

      function createXMLHttpRequest()
      {
      try { return new XMLHttpRequest(); } catch(e) {}
      try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
      return null;
      }

      var url = "http://www.finansportalen.no/services/sph/produkt/list/";
      var xhReq = createXMLHttpRequest();
      xhReq.open("GET", url, false);
      xhReq.send(null);

      var sphdata = eval(xhReq.responseText);

      **********************************************

      (I would have prefered, however, to have the object declared by the server
      and posted as a .js file i could simply include, thus enabling me to
      access it directly. But the above will do.)

      Thanks again!





      Here are several patterns I often use which may help you

      *If the list data is available at the time your server is
      returning the rest of the page content
      *
      Pattern.1:

      Have the server emit a script tag that pulls in
      your javascript code for doing something with the list,
      say a function called handleMyList.

      Have the server then emit (within script tags)
      handleMyList( [ item1, item2, item2 ] );


      Pattern.2:

      Have the server emit (within script tags)
      var listArr = [ item1, item2, item3 ];

      Then have the server emit a script tag that
      pulls in your javascript code for doing something
      with listArr.



      *If you need to request the list after the user has
      done other selections:*

      This is quite similar to Pattern.1, but you
      would use an AJAX style request to get the
      content back.

      *OR, to do it "by hand"*

      On your HTML page
      define an iframe IFR
      define a form F
      with action: serverUrl
      target: IFR
      and hidden fields for any parameters
      you need to pass

      When the user makes their selection
      F.parm1.value = "..."
      F.submit();

      Have the server return (within script tags)
      parent.top.handleMyList( [ item1, item2, item3 ]);

      Connie


      On Thu, May 19, 2011 at 6:47 AM, jonerlandmadsen <
      jon.erland.madsen@...> wrote:

      >
      > Hi!
      >
      > I am trying to get an answer to what must be JSON-question number two,
      > but
      > apparently, the answer to my question is too obvious to be included in
      > the
      > Q&As I've found.
      >
      > I will use an external JSON-array in my javascript. It originates from
      > our
      > own server, so there are no security concerns.
      >
      > The address is be for instance:
      >
      > http://www.mysite.no/services/product/list/
      >
      > According to Wikipedia, I can make an object out of it, using "eval".
      > The
      > example given is:
      >
      >
      > var p = eval("(" + contact + ")");
      >
      >
      > ..where 'contact' is the json array contained in a text object.
      >
      > But there must be a step between, that is not explained. The
      > aforementioned external json array has no name. It just starts with a
      > paranthesis [
      >
      > I would thus have to convert it into a string first. How do I do that
      > (javascript does not allow you to read external files into a string, as
      > for
      > instance php does).
      >
      > Can I convert a json array directly using the url as an argument in
      > eval()
      > (probably not)?
      >
      > I have programmed for 20 years (!) but never used JSON. I feel like a
      > complete fool. I've searched the internet two hours for the answer to
      > this. Even googling json+dummies or json+newbie didn't help. They all
      > write
      > about different parsers.
      >
      > If you could help me, I would be very grateful.
      >
      >
      >
      >
      >
      >
      >
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >


      [Non-text portions of this message have been removed]
    • kylealanhale
      I want to clarify a couple of things that no one else seems to have addressed: * There is no such thing as an external JSON-array ; JSON is just a data
      Message 2 of 8 , May 20, 2011
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        I want to clarify a couple of things that no one else seems to have
        addressed:
        * There is no such thing as "an external JSON-array"; JSON is just a
        data transfer format, or, more correctly, a data transfer notation
        (JavaScript Object Notation). What you described in your last post, of
        defining the array in a javascript file that you include in your page,
        is not JSON at all, just JavaScript.
        * You should never transfer JSON-encoded data as an array; this opens a
        security vulnerability (see
        http://directwebremoting.org/blog/joe/2007/03/05/json_is_not_as_safe_as_\
        people_think_it_is.html for a good summary of the issue); instead,
        always enclose it in an object. So instead of your data looking like
        [{"key1": "value1"}, {"key2": "value2"}...], make it look like {"list":
        [{"key1": "value1"}, {"key2": "value2"}...]}.
        * You should also never use eval(), for reasons that have been explained
        extensively elsewhere, including several times by the brainfather of
        JSON himself, and in the very Wikipedia article you quoted from
        originally <http://en.wikipedia.org/wiki/JSON#Security_issues>. Instead
        use JSON.parse, which is standard in all major browsers now.
        * If you want to get a JavaScript object from a JSON-encoded source
        while working from the browser, you will invariably use XHR (AJAX, if
        you must). The method you posted is exactly how you would do that, with
        the exception that you'd probably want to do it asynchronously and
        handle the data in a callback, rather than procedurally. Also, if you
        use a JavaScript framework, it will generally make your life much easier
        and your code much cleaner. A jQuery example:
        $.getJSON('http://www.mysite.no/services/product/list/', function(data)
        { $.each(data.list, function (index, listItem) { // Do something
        which each item in the list });});
        Note that this function takes care of (safely) decoding your
        JSON-encoded data so that you can handle it as a native JavaScript
        object. See http://api.jquery.com/jQuery.getJSON/ and
        http://api.jquery.com/jQuery.ajax/ for more details.
        * While there are exceptions to all of these, and things I have left
        out, this is a good starting place for best-practices, I think.


        --- In json@yahoogroups.com, jon.erland.madsen@... wrote:
        >
        > Thank you so very much!
        >
        > I got help and will use the following code (my script is client side):
        >
        > **********************************************
        >
        > function createXMLHttpRequest()
        > {
        > try { return new XMLHttpRequest(); } catch(e) {}
        > try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
        > return null;
        > }
        >
        > var url = "http://www.finansportalen.no/services/sph/produkt/list/";
        > var xhReq = createXMLHttpRequest();
        > xhReq.open("GET", url, false);
        > xhReq.send(null);
        >
        > var sphdata = eval(xhReq.responseText);
        >
        > **********************************************
        >
        > (I would have prefered, however, to have the object declared by the
        server
        > and posted as a .js file i could simply include, thus enabling me to
        > access it directly. But the above will do.)
        >
        > Thanks again!
        >



        [Non-text portions of this message have been removed]
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