将值分配给可观察到的淘汰赛？

Question

I have a page that populates its fields(dropdowns and textboxes) from the DB when the page loads via VIEWDATA object from controller.

I am using KnockoutJS for data-binding, below is the scenario

HTML & JS(dropdown)

@if (Filter!= null)
{
    <select  data-bind="options: RsnAdmAct, 
                        value: selectedRsnAdmAct, 
                        optionsCaption:'Choose...', 
                        optionsValue:'RsnAdminActionID', 
                        optionsText:'RsnAdminActionDescp',
                        optionsAfterRender: function()
                        {
                            setOptionRSN(@Filter.RsnForAdminAction);
                        }">
     </select>
}


self.RsnAdmAct = ko.observableArray([]);
self.selectedRsnAdmAct = ko.observable();
$.getJSON("GetRAA", null, function (data) {
    self.RsnAdmAct(data);
});

self.selectedRsnAdmAct = ko.observable();
self.setOptionRSN = function (x) {//reason for admin action dd
    self.selectedRsnAdmAct(x);
};

this does update the drop-down with the assigned value " X ".

But the same does not assign value for the text-boxes as below

HTML & JS(textbox)

@if (@Filter != null)
{
    <input placeholder="Downstream"  
           data-bind="value: DownStream,
                      optionsAfterRender:function()              
                      {
                         setOptionDstream(@Filter.DownstreamNumber);
                      }">
 }

 self.DownStream = ko.observable();   
 self.setOptionDstream = function (x) {//down stream number
     self.DownStream(x);
 };  

Answer 1

optionsAfterRender applies to options; a text input has no options. Setting the value of DownStream will set the value of the text box, because that's how the value binding works.

Answer 2

I tried to search for a proper way to do this but below is the way it works and no other alternative worked.I had to move the function which assigns the value to the texbox observable into the options after render attribute of the drop down as below

@if (Filter!= null)
{
<select  data-bind="options: RsnAdmAct, 
                    value: selectedRsnAdmAct, 
                    optionsCaption:'Choose...', 
                    optionsValue:'RsnAdminActionID', 
                    optionsText:'RsnAdminActionDescp',
                    optionsAfterRender: function()
                    {
                        setOptionRSN(@Filter.RsnForAdminAction);
                        setOptionDstream(@Filter.DownstreamNumber);
                    }">
 </select>
}

This is the only way it worked for me.Thank you for the posts and comments