php foreach 带有选定标签的表单下拉菜单

Question

伙计们，我有一个下拉列表，当我按下按钮时，我想自动标记所选行！到目前为止，我的代码如下所示，但我无法让它工作......使用 ' " 等

echo "<select id='form' name=form style='width:auto' class='form-control'>
<optgroup label='form_name'>";

foreach($results as $result)                                    
{
    $ID      = $result->ID;
    $name    = $result->name;
    $address = $result->address;

    echo '<option value=$ID '. 

    **if(isset($_GET['form']) &&  $_GET['form'] == $ID ){  .' selected="selected" '. } else { .''. }**                               

    .'>'.$ID. ". " .$name. " [" .$address.']</option>'; 

}                               
echo "</optgroup>
</select>;

提前致谢！！！

Answer 1

您可以这样重写代码：

echo "<select id='form' name=form style='width:auto' class='form-control'>
    <optgroup label='form_name'>";
    foreach($results as $result)                                    
    {
        $ID      = $result->ID;
        $name    = $result->name;
        $address = $result->address;

        $selected = ( isset($_GET['form']) &&  $_GET['form'] == $ID ) ? ' selected="selected" ' : '';

        echo '<option value=$ID '
                . $selected
                .'>'.$ID. ". " .$name. " [" .$address.']</option>'; 
    }                               
echo " </optgroup>
           </select>;

Answer 2

您必须使用 ternary 运算符。三元运算符是一个简单的 "if then else"，仅一行。

echo '<select id="form" name="form" style="width:auto" class="form-control">';
    echo '<optgroup label="form_name">';

    foreach ($results as $result) {
        $id      = $result->ID;
        $name    = $result->name;
        $address = $result->address;

        echo '<option value="' . $id . '" ' . (isset($_GET['form']) && $_GET['form'] == $id ? 'selected="selected"' : '') . '>' . $id . '. ' . $name . ' [' . $address . ']</option>';
    }

    echo '</optgroup>';
echo '</select>';

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