我想当页面加载时,如果$a=x,那么option1出现在选择表单中,如果$a=y, option2出现在选择表单中,否则选择应该出现。我怎样才能做到这一点呢?
下面所有的代码都在一个表的每一行中,并且行数未知。
PHP: $a;
echo "<div class='res'> State:";
if ($a[0]!="") $a=x;
else if ($b[0]!="") $a=y;
else echo "None";
echo "<form class='form-horizontal'>
<fieldset >
<span class='control-group' >
<span class='controls'>
<select id='fl' class='form-control' style='cursor:pointer;'>
<option selected='selected' style='display:none;' value='0'>Select</option>
<option value='1'>Option1</option>
<option value='2'>Option2</option>
</select>
</span>
</span>
<div><button id='mybtn' type='button'>Save</button></div>
</fieldset>
</form>";
echo "</div";
switch($a) {
case 'x':
$default = 1;
break;
case 'y':
$default = 2;
break;
default:
$default = 0;
}
echo "<form class='form-horizontal'>
<fieldset >
<span class='control-group' >
<span class='controls'>
<select id='fl' class='form-control' style='cursor:pointer;'>
<option " . ($default == 0 ? "selected='selected'" : "") . " style='display:none;' value='0'>Select</option>
<option " . ($default == 1 ? "selected='selected'" : "") . " value='1'>Option1</option>
<option " . ($default == 2 ? "selected='selected'" : "") . " value='2'>Option2</option>
</select>
</span>
</span>
<div><button id='mybtn' type='button'>Save</button></div>
</fieldset>
</form>";
我将创建一个选项数组,如:
$option = [0=>'select', 1=>'option1', 2=>'option2' ...];
然后,创建你的选择框;循环遍历数组:
带有选择适当默认值的条件。
foreach($option as $k=>$v){
if( <your condition> ){
$selected = 'selected';
}else{
$selected = "";
}
echo "<option value='$k' '$selected'>$v</option>;
}
如果条件很简单,可以使用三元操作符来简化代码。$selected = (condition) ? 'value for true' : 'value for false';
在回显前添加以下代码:
$option1 = '';
$option2 = '';
$showDefault = "<option value=''>Select</option>";
if ($a == $x) {
$option1 = 'selected';
$showDefault = '';
} else if ($a == $y) {
$option2 = 'selected';
$showDefault = '';
}
然后将HTML选项改为:
"$showDefault
<option value='1' $option1 >Option1</option>
<option value='2' $option2 >Option2</option>"
这将允许你隐藏选项"Select",除非它是必要的。还有其他的方法,但是这种方法非常直接
你不需要"selected='selected'",只需要"selected ":
<option selected value='0'>Selected</option>
通常,我用三元语句设置它们,如:
?>
<option <?=$a=='':'selected'?''?> value='0'>Select</option>
<option <?=$a=='x':'selected'?''?> value='1'>Option 1</option>
<option <?=$a=='y':'selected'?''?> value='2'>Option 2</option>
<?