Checking if an instance's class implements an interface?

Question 1

Wilco’s Question:

Given a class instance, is it possible to determine if it implements a particular interface? As far as I know, there isn’t a built-in function to do this directly. What options do I have (if any)?

Answer

nlaq

interface IInterface
{
}

class TheClass implements IInterface
{
}

$cls = new TheClass();
if ($cls instanceof IInterface)
    echo "yes"

You can use the “instanceof” operator. To use it, the left operand is a class instance and the right operand is an interface. It returns true if the object implements a particular interface.

Answer

Starx

You can also do the following

public function yourMethod(YourInterface $objectSupposedToBeImplementing) {
   //.....
}

It will throw an recoverable error if the $objectSupposedToBeImplementing does not implement YourInterface Interface.

Question 2

Abc123’s Question:

abc123

How do I select the entire h4 node that doesn’t contain h3 with class=”avoid”? In this case I want to select the first and fourth h4 node.

<div>
<h4>
    <h1><h1>
    <h2><h2>
</h4>
<h4>
    <h1><h1>
    <h2><h2>
    <h3 class="avoid"><h3>
</h4>
    <h4>
    <h1><h1>
    <h2><h2>
    <h3 class="avoid"><h3>
</h4>
<h4>
    <h1><h1>
    <h2><h2>
</h4>
</div>

Answer

Starx

First of all. Having heading tags inside another is not valid. Saying that..

CSS is not capable of selecting a parent based on nested elements.

You need JS to do such selections. A good read is this.

Question 3

Dan Costinel’s Question:

Dan Costinel

I have the following code, for learning porpose. In short, I want to grab some data from a database, with the help of a drop-down menu. My problem is that now I’m using a submit button to make the submit action. And the improvement that I want, is to get rid of the submit button, and grab the infos when the drop-down changes.

I’ve tried to make a function for the code between line 1 and 12, and call it with: <body onload="process()">, but it’s not working. Then I tried to put the onchange="this.form.submit()" attribute to the <select> element, but this doesn’t work also, because it sends the data to process.php like any normal submission when not using ajax.
Anyone know any fix? Thank you!

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
</head>
<body onload="viewdata()">
    <form action="process.php" method="post" id="form">
        <select name="select" id="select">
            <option value="">Choose</option>
            <option value="1">supervizor</option>
            <option value="2">sef locatie</option>
            <option value="3">muncitor</option>
            <option value="0">toti</option>
        </select><br/>
        <input type="submit" value="Go"/>
    </form>
    <script type="text/javascript">
    var frm = $('#form'); // **LINE 1**
    frm.submit(function (ev) {
        $.ajax({
            type: frm.attr('method'),
            url: frm.attr('action'),
            data: frm.serialize(),
            success: function (data) {
                $('#show').html(data);
            }
        });
        ev.preventDefault();
    });                    // **LINE 12**

    function viewdata(){
        $.ajax({
            type: "GET",
            url: "process.php"
        }).done(function( data ) {
            $('#show').html(data);
        });
    }
    </script>
    <br/><br/>
    <div id="show"></div>
</body>
</html>

Answer

Starx

You need to bind your processing on the change event of your drop down box.

$("#select").on("change", function(ev) {
    // Your ajax processing
    $.ajax({
        type: frm.attr('method'),
        url: frm.attr('action'),
        data: frm.serialize(),
        success: function (data) {
            $('#show').html(data);
        }
    });
    ev.preventDefault();
});

Month: August 2015

Checking if an instance's class implements an interface?

Wilco’s Question:

css selector for a node which doesn't contain a given selector with class attribute

Abc123’s Question:

Dispose submit button with ajax-jquery and php

Dan Costinel’s Question:

Please fill the form - I will response as fast as I can!