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Thread: JavaScript function with AJAX

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  1. #1
    Join Date
    Jan 2013
    Posts
    5

    JavaScript function with AJAX

    Hi everybody!

    I want to load one listbox on the basis of the another in Java. The following function should work while I change country list.

    <script>
    function loadCountryRegion() {
    var selectedCountryName = document.getElementById("listCountry").value;
    $('#listCountryRegion').html('');
    $.ajax({
    type : 'GET',
    dataType : 'json',
    url : 'cs?action=getCountryRegionList&listCountry='+ selectedCountryName,
    success : function(data) {
    $.each(data.CountryRegionList, function(i, region) {
    $("#listCountryRegion").append(
    '<option value="' + region.name +'">'
    + region.name + '</option>');
    });
    },

    });
    }
    </script>

    But selectedCountryName is null. It doesn't contain the country name.

    Could you please advise why it is null and what should I do?

    Thanks

  2. #2
    Join Date
    Aug 2008
    Location
    Sweden
    Posts
    227
    Well, is the element with the id listCountry a <select> or other type of input element?

    (Also, JavaScript is not the same as Java.)
    New to web development or in need of a good reference? Check out the Mozilla Developer Network or W3Schools.

  3. #3
    Join Date
    Jan 2013
    Posts
    5
    listCountry is the id of 1st listbox (<select>) and listCountryRegion is the id of 2nd which I would like to populate based
    on the 1st one.
    I am developing my project using Java web technologies so I need to work with JQuery, Ajax, HTML, Javascript.
    Variable selectedCountryName does not get country name from the listbox and I am wondering why? Maybe page is not
    refreshed?

  4. #4
    Join Date
    Aug 2008
    Location
    Sweden
    Posts
    227
    If listCountry is an existing select element then document.getElementById("listCountry").value should be a string no matter what. If listCountry would be another kind of element than a select element, for example a paragraph, then the value property should be undefined, not null. Are you sure it's not document.getElementById("listCountry") that returns null? If that's the case then listCountry simply does not exist. (Maybe there's a misspelling somewhere.)
    New to web development or in need of a good reference? Check out the Mozilla Developer Network or W3Schools.

  5. #5
    Join Date
    Jan 2013
    Posts
    5
    No, there is no misspelling. When I select the country name from the drop down list function does not get the name but when I click on submit button it gets. So I am wandering why it happens?

  6. #6
    Join Date
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    Location
    Sweden
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    Could you post the html code?
    New to web development or in need of a good reference? Check out the Mozilla Developer Network or W3Schools.

  7. #7
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    Vic

    God loves you and will never love you less.

    http://www.vicsjavascripts.org/Home.htm
    If my post has been useful please donate to http://www.operationsmile.org.uk/

  8. #8
    Join Date
    Jan 2013
    Posts
    5
    The code is as below:

    <script>
    function loadCountryRegion() {
    var selectedCountryName = document.getElementById("listCountry").value;
    $('#listCountryRegion').html('');
    $.ajax({
    type : 'GET',
    dataType : 'json',
    url : 'cs?action=getCountryRegionList&countryName='+ selectedCountryName,
    success : function(data) {
    $.each(data.CountryRegionList, function(i, region) {
    $("#listCountryRegion").append(
    '<option value="' + region.name +'">'
    + region.name + '</option>');
    });
    },


    });

    }
    </script>

    <form action="cs?action=saveDistrict" method="post">
    <select name = "listCountry" id="listCountry" onchange="loadCountryRegion();">
    List<Country> countryList = (List<Country>) request.getAttribute(Constants.COUNTRY_LIST);
    <%for (Country country:countryList){ %>
    <option name = <%=country.getCountryName() %>><%=country.getCountryName() %></option>
    %} %>
    </select>

    <select name = "listCountryRegion" id = "listCountryRegion">
    <%-- List<Region> regionList = (List<Region>) request.getAttribute(Constants.REGION_LIST);
    for (Region region:regionList){ --%>
    <option value = ''Choose Region''></option>
    <%--} --%>
    </select>
    District: <input type="text" name="txtDistrict"/>
    <input type="submit" name = btnSaveDistrict value = "Add District"/>
    </form>


    When I choose country name from drop-down box and submit the button it takes and saves the name, but function does not get.

  9. #9
    Join Date
    Aug 2008
    Location
    Sweden
    Posts
    227
    Well, uh, if I change the <% code... %> to something appropriate it works in Chrome and Firefox though not in IE, but you should really take a closer look at your HTML code.

    Code:
    <select name = "listCountry" id="listCountry" onchange="loadCountryRegion();">
    List<Country> countryList = (List<Country>) request.getAttribute(Constants.COUNTRY_LIST);
    <%for (Country country:countryList){ %>
    Pretty sure that's supposed to be inside the <% %>

    Here you're missing quotation marks around the value for the name attribute:
    Code:
    <option name = <%=country.getCountryName() %>><%=country.getCountryName() %></option>
    And here you've surrounded the attribute value with two single quotation marks instead of using double quotation marks:
    Code:
    <option value = ''Choose Region''></option>
    There's nothing wrong with the JavaScript.
    New to web development or in need of a good reference? Check out the Mozilla Developer Network or W3Schools.

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