其他过滤器上的过滤器下拉列表

Question

Hey guys I know it had been discussed so much but I still don't get it working.

What I need is to filter a gridview by a few dropdown lists and the main idea is to "continue" filtering the gridview. I mean, when I select value from ddl1, then the ddl2 is filtered according to the selected value in ddl1.

Also called cascading dropdown list but I don't want to (can not) use Ajax Control Toolkit...

Any other solutions to that? Maybe the method protected void DropDownList2_SelectedIndexChanged(...) can do this but I don't know how to use it.

Please help Thanks in advance.

Answer 1

Have a look at the below. It is just to give you an idea...

DropDownList1_SelectedIndexChanged(...){
// get the ddl1 selected value
// filter the datasource used by dropdownlist2
// databind DropDownList2 
}

DropDownList2_SelectedIndexChanged(...){
    // get the ddl1 selected value 
    // get the ddl2 selected value 
    // filter the datasource used by GridView(using the DropDownList selected values)
    // databind GridView 
}

Answer 2

I would suggest to use Jquery to fill cascaded dropdownlists. Add this script to your webpage.

$(document).ready(function () {

$("#<%= ddlState.ClientID %>").change(function () {

var sourceddl = "<%= ddlState.ClientID %>";
var stateid = $("#<%= ddlState.ClientID %> option:selected").val();
var Stateid = { Stateid: stateid };

$.ajax({
                type: 'POST',
                url: 'YourCodeBehind.aspx/GetCounties',
                data: JSON.stringify(Stateid),
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (result) {                       
                          if (data.d) { 
                          var options = [];                     
                          if (result.d) {
                          for (var i = 0; i < result.d.length; i++) {
                               options.push('<option value="',
                                              result.d[i].countyID, '">',
                                              result.d[i].countyName, '</option>');
                            }

                            $("#<%= ddlCounty.ClientID %>").html(options.join(''));
                        }                        
                     }
                },
                error: function () {
                    alert("Error! Try again...");
                }
            });

        });

    });

here is the webmethod which is in the same codebehind.

[WebMethod]
public static County[] GetCounties(int Stateid)
{
    County[] countiesArr = StatesCountyModel.GetCountyForState(Stateid).ToArray();
    return countiesArr;     
}

If you are new to Jquery. go through the http://Jquery.com to understand how to use it.

Hope it helps.

Praveen