PHP：两个 <select> ，第一个已经准备好填充，第二个我想填充值

Question

I am have this issue:

<fieldset>
<?php
    echo form_open('rssFeedReader/addSource');

    echo '<h2><small>(*) Select in which category you want to add a new Rss Source </small><h2>';

    echo '<div class="form-group">';
        echo '<select class="form-control input-lg" name="category" id="category">';
        foreach( $categories as $row )
        {
            // here i have some values from my database
            echo '<option value="'.$row->id.'">' . $row->category_name . '</option>';
        }
        echo '</select>';
    echo '</div>';

   // NOW, HERE I WANT TO PUT ANOTHER <SELECT>
        echo '<div class="form-group">';
        echo '<select class="form-control input-lg" name="anotherID" id="anotherID">';
        foreach( $array as $r)
        {
            // here i have some values from my database
            echo '<option value="'.$r->something.'">' . $r->something_else. '</option>';
        }
        echo '</select>';
        echo '</div>';



    echo '<div class="form-group">';
        echo form_submit(array('class' => 'btn btn-primary btn-lg btn-block', 'id' => 'remove_source', 'name' => 'remove_source', 'value' => 'Remove Source'));
    echo '</div>';
?>

<?php echo validation_errors('<p class="error">'); ?>

Now, what I want to do. The second select list is empty initially. I want to fill it with values depending of what is chose in first select list.

How can I do that? To fill the second select list only if something is selected in first select list.

Answer 1

MrCode has a nice example for you.

Using Ajax To Populate A Select Box

<script type="text/javascript" charset="utf-8">
    $(document).ready(function(){
        $('#category').on('change', function (){
            $.getJSON('select.php', function(data){
            var options = '';
            for (var x = 0; x < data.length; x++) {
                options += '<option value="' + data[x]['id'] + '">' + data[x]['name'] + '</option>';
            }
            $('#anotherID').html(options);
        });
    });
});
</script>

Your select.php should json_encode() the data which you want to fill your select with

Answer 2

The best way to handle this would be to populate the list after you made a change on the first list. For example.

$("#category").on("change", function(){
    var selectedValue = $(this).val();
    $.get("some.php?value=" + selectedValue, function(response){
        var options = "";
        for(var i = 0; i < response.length;i++){
            var val = response[i];
            options += "<option value='" + response[i].id + "'>" + response[i].name + "</option>";
        }
        $("#anotherID").empty().append(options);

    });
}

I had to make several assumptions. for example your some.php will take a value parameter. The return is json array [{id:1, name:"option 1"}, {id:2, name:"option 2"}]. Please keep this in mind.