Value from dynamically poulate Dropdownlist

Niall Gallagher
Niall Gallagher used Ask the Experts™
on
I have 2 DropDown lists on a page showing departments and positions.  When a user changes a department in the dropdown the other should populate with the positions available in that Dept.
I found a bit of code and altered it to do my job
        $("#ddlDept").change(function() {
             if ($("#ddlDept").val() != "-1") {
                 var deptid = $(this).val();
                 var posid = $("#ddlPosition").val();
                 $.getJSON("/Details/GetPositionByDept", { selectedDeptID: deptid },
                        function(dropdowndata) {
                            var select = $("#ddlPosition");
                            select.empty();
                            select.append($('<option/>', { value: 0, text: "Select Position" }));
                            $.each(dropdowndata, function(index, itemData) {
                                select.append($('<option/>', {
                                    value: itemData.valueOf,
                                    text: itemData.Text
                                }));

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and it populates great but what I want is it will select the position which has the same value as posid.

I have tried $("#ddlPosition").val(posid); but it does nothing>
also wrote a function for catching the value of the ddlPosition onChange
  $("#ddlPosition").change(function() {
         alert($("#ddlPosition").val());
     });

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but it returns [object HTMLOptionElement]
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Most Valuable Expert 2018
Distinguished Expert 2018
Commented:
You need to get the value of the selected option, not the value of the dropdown itself:

var posid = $(":selected", "#ddlPosition").val();
...
$("#ddlPosition").val(posid);

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This will only work if the selected option is still available after your JSON request
Scott FellDeveloper & EE Moderator
Fellow 2018
Most Valuable Expert 2013

Commented:
Can you provide some sample data and the rest of your code.

In the meantime, I have had good success using http://www.appelsiini.net/projects/chained for multiple selects.

The way it works is you send all of your data to the browser at once and set the class of the 2nd option group to match the value of the first.  When you select the first group, the 2nd only shows classes that match the first.
<select id="mark" name="mark">
  <option value="">--</option>
  <option value="bmw">BMW</option>
  <option value="audi">Audi</option>
</select>
<select id="series" name="series">
  <option value="">--</option>
  <option value="series-3" class="bmw">3 series</option>
  <option value="series-5" class="bmw">5 series</option>
  <option value="series-6" class="bmw">6 series</option>
  <option value="a3" class="audi">A3</option>
  <option value="a4" class="audi">A4</option>
  <option value="a5" class="audi">A5</option>
</select>

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Niall GallagherDeveloper

Author

Commented:
Chris,
that works great for that part and Thank you
The reason I was trying to check if that works is because I want to set the selected value

Would this work then
$(":selected", "#ddlPosition").val(posid);
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Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
If you want to set the selected value of the second dropdown, just use the code you already have:

$("#ddlPosition").val(posid);
Niall GallagherDeveloper

Author

Commented:
Chris,
I tried that and it did nothing. I tried it in a few places this is the last one

 <script type="text/javascript">
     $(document).ready(function() {
         $("#ddlDept").change(function() {
             if ($("#ddlDept").val() != "-1") {
                 var deptid = $(this).val();
                 var posid = $(":selected", "#ddlPosition").val();
                 $.getJSON("/Details/GetPositionByDept", { selectedDeptID: deptid },
                        function(dropdowndata) {
                            var select = $("#ddlPosition");
                            select.empty();
                            select.append($('<option/>', { value: 0, text: "Select Position" }));
                            $.each(dropdowndata, function(index, itemData) {
                                select.append($('<option/>', {
                                    value: itemData.valueOf,
                                    text: itemData.Text
                                }));
                            });
                        });
                        
             };
         });
     });
     $("#ddlPosition").val(posid);
 </script>

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Niall GallagherDeveloper

Author

Commented:
Chris,
Your answer was right although I haven't got it going 100% yet but I noticed the biggest part of my problems were coming from
value: itemData.valueOf,
   text: itemData.Text

When I checked my code the itemData.valueOf should have been itemData.Value
Niall GallagherDeveloper

Author

Commented:
Thanks that worked great.
Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
OK. It needs to go after the $.each() block, but like I said - it will only work if the value still exists in the #ddlPosition dropdown after you've rebuilt it

 <script type="text/javascript">
     $(document).ready(function() {
         $("#ddlDept").change(function() {
             if ($("#ddlDept").val() != "-1") {
                 var deptid = $(this).val();
                 var posid = $(":selected", "#ddlPosition").val();
                 $.getJSON("/Details/GetPositionByDept", { selectedDeptID: deptid },
                        function(dropdowndata) {
                            var select = $("#ddlPosition");
                            select.empty();
                            select.append($('<option/>', { value: 0, text: "Select Position" }));
                            $.each(dropdowndata, function(index, itemData) {
                                select.append($('<option/>', {
                                    value: itemData.valueOf,
                                    text: itemData.Text
                                }));
                            });

                            $("#ddlPosition").val(posid);

                        });
             };
         });
     });
 </script>

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Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
Ahhh. Looks like we cross-posted :)
Niall GallagherDeveloper

Author

Commented:
By the way your last comment about moving the $("#ddlPosition").val(posid); worked great

Thanks again

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