Create A Php Dropdown List

Summary: in this tutorial, you will learn how lớn use the element khổng lồ create a drop-down list and a list box and how lớn get the selected values from the element in PHP.

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A quick introduction to lớn the element

The is an HTML element that provides a các mục of options. The following shows how to define a element in HTML:

label for="color">Background Color:label>select name="color" id="color">option value="">--- Choose a màu sắc ---option>option value="red">Redoption>option value="green">Greenoption>option value="blue">Blueoption>select>
Code language: HTML, XML (xml)The element has two important attributes:

id – the id associates the element with a elementname – the name attribute associates with the value for a size submission.

The element nested inside the element defines an option in the menu. Each option has a value attribute. The value attribute stores data submitted lớn the vps when it is selected.

If an option doesn’t have the value attribute, the value attribute defaults khổng lồ the text inside the element.

To select an option when the page loads for the first time, you can showroom the selected attribute to lớn the element.

The following example selects the Green option when the page first loads:

label for="color">Background Color:label>select name="color" id="color">option value="">--- Choose a màu sắc ---option>option value="red">Redoption>option value="green" selected>Greenoption>option value="blue">Blueoption>select>
Code language: HTML, XML (xml)

Getting the selected value from a element

We’ll create a khung that uses a element.

First, create the following folders & files:

Code language: HTML, XML (xml)Third, place the following code in the footer.php file:

Code language: HTML, XML (xml)Fourth, địa chỉ cửa hàng the following code to the get.php file to create a khung that has one element with a submit button:

form action="" method="post"> div> label for="color">Background Color:label> select name="color" id="color"> option value="">--- Choose a màu sắc ---option> option value="red">Redoption> option value="green" selected>Greenoption> option value="blue">Blueoption> select> div> div> button type="submit">Selectbutton> div>form>
Code language: HTML, XML (xml)The khung uses the POST method lớn submit data to the webserver.

Finally, địa chỉ cửa hàng the following code to lớn the post.php file:

$color = filter_input(INPUT_POST, "color", FILTER_SANITIZE_STRING);?> if ($color) : ?> p>You selected span style="color:"> echo $color ?>span>p> p>a href="index.php">Back khổng lồ the forma>p> else : ?> p>You did not select any colorp> endif ?>
Code language: HTML, XML (xml)To get the selected value of the element, you use the $_POST superglobal variable if the size method is POST & $_GET if the khung method is GET.

Alternatively, you can use the filter_input() function khổng lồ sanitize the selected value.

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If you select the first option of the element, the selected value will be empty. Otherwise, the selected value is red, green, or blue.

Select with multiple options

To enable multiple selections, you địa chỉ the multiple attribute to lớn the element:

select name="colors<>" id="colors" multiple>...select>
Code language: HTML, XML (xml)When you select multiple options of a element & submit the form, the name will contain multiple values rather than a single value. To get multiple selected values, you địa chỉ cửa hàng the square brackets (<>) after the name of element.

Let’s take a look at an example of using a element with multiple selections.

First, create the following folders and files:

Code language: HTML, XML (xml)Third, add the following code to the footer.php file:

Code language: HTML, XML (xml)Fourth, include the header.php and footer.php files in the index.php:

require __DIR__ . "/inc/header.php";$request_method = strtoupper($_SERVER<"REQUEST_METHOD">);if ($request_method === "GET") require __DIR__ . "/inc/get.php"; elseif ($request_method === "POST") require __DIR__ . "/inc/post.php";require __DIR__ . "/inc/footer.php";
Code language: HTML, XML (xml)If the HTTP request is GET, the index.php file will show a size from the get.php file. When the khung is submitted, the post.php tệp tin will handle the khung submission.

Fifth, create a size that contains a element with the multiple attribute in the get.php file. The name of the element has an opening và closing square bracket <> so that PHP can create an array that holds the select values.

form action="" method="post"> div> label for="colors">Background Color:label> select name="colors<>" id="colors" multiple> option value="red">Redoption> option value="green">Greenoption> option value="blue">Blueoption> option value="purple">Purpleoption> option value="magenta">Magentaoption> option value="cyan">Cyanoption> select> div> div> button type="submit">Submitbutton> div>form>
Code language: HTML, XML (xml)Finally, handle the khung submission in the post.php file:

$selected_colors = filter_input(INPUT_POST,"colors",FILTER_SANITIZE_STRING,FILTER_REQUIRE_ARRAY);?> if ($selected_colors) : ?>p>You selected the following colors:p>ul> foreach ($selected_colors as $color) : ?>li style="color:"> echo $color ?>li> endforeach ?>ul>p>p> else : ?>p>You did not select any color.p> endif ?>a href="index.php">Back lớn the forma>
Code language: HTML, XML (xml)The post.php tệp tin uses the filter_input() function lớn get the selected colors as an array. If you select one or more colors, the post.php file will display them.

Summary

Use the element lớn create a dropdown list.Use the multiple attribute to create a danh mục that allows multiple selections.Use $_POST to lớn get the selected value of the select element if the size method is POST (or $_GET if the form method is GET).Add square brackets(<>) after the name of the element to get multiple selected values.
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