PHP如果变量等于下拉列表中的值，则将“selected”属性添加到选项中

问题描述：

I have a drop down menu that checks whether a user has already selected a value by checking database and if they have, I want to add a 'selected' attribute to that option so that when they edit their profile, that option is preselected by what they chose.

Heres an example of what I am trying to accomplish. It works for text inputs but I don't know how to do it with dropdown lists.

So if user selects 'Dog', it gets place in database and adds 'selected' as attribute

$animal = $mysqli->escape_string($_POST['animal']);
//PHP UPDATE database script -------->

<label>Animal</label></br>
    <select name='animal' value='<?php if($animal == value){ /*Add selected attribute to option */ ?>'>
         <option value="" disabled selected>Select One</option>
         <option value="" disabled>----------------</option>
         <option value="Dog">Dog</option>
         <option value="Cat">Cat</option>
         <option value="Bird">Bird</option>  
    </select>

答

Define an array of options

$animals = ['Dog', 'Cat', 'Bird'];

Then generate the list of options for the <select> from that array, checking the selected animal against each one. If it matches, then add the selected attribute.

<label>Animal</label></br>
<select name='animal'>
     <!-- select the default if none of the options are selected -->
     <option value="" disabled <?php if (!in_array($animal, $animals)) echo 'selected' ?>>
         Select One
     </option>
     <option value="" disabled>----------------</option>
     <?php foreach ($animals as $option) {
        echo "<option ";
        if ($animal == $option) {
            echo 'selected';
        }
        echo ">$option</option>"; 
     ?>
</select>

value attributes aren't required for your <option> elements in this case, since you're using the same values for the option text. (If the value attribute is omitted, the option text will be used as the value.)

答

Try it like this:

$animal = $mysqli->escape_string($_POST['animal']);
//PHP UPDATE database script -------->

echo '<label>Animal</label></br>
    <select name="animal">
         <option value="" disabled>Select One</option>
         <option value="" disabled>----------------</option>
         <option value="Dog" ' . ($animal == 'Dog' ? 'selected' : '') . '>Dog</option>
         <option value="Cat" ' . ($animal == 'Cat' ? 'selected' : '') . '>Cat</option>
         <option value="Bird" ' . ($animal == 'Bird' ? 'selected' : '') . '>Bird</option>  
    </select>';

PHP如果变量等于下拉列表中的值，则将“selected”属性添加到选项中

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